Smog Through Brakes?
I had an odd smog repair last month so I thought it would be useful in discussing vehicle communications networks and modules. A module is a microprocessor (more than 50 in some modern vehicles) and they communicate via an onboard network to share data. My new customer inherited a 97 BMW 540I and asked us to evaluate its condition and perform a Smog Inspection for transfer of title. The customer’s priorities were correct: SMOG FIRST. My advice is don’t spend money fixing a vehicle that won’t pass a smog inspection; you can’t drive it.
Just to digress here with a warning to all, in California the seller is REQUIRED to provide the buyer with a currently passed smog inspection certificate. This law protects buyers from predatory sellers. You may think the purchase price is a really good deal but without a smog certificate you may have additional costs getting the vehicle to pass a smog inspection. DO NOT purchase a vehicle without a smog inspection certificate.
This BMW’s “Check Engine Light” was on. That’s an automatic smog failure. The “Traction Control” light (TC) was also on but since it’s not emissions related, OR SO I THOUGHT, I put it on hold for now. Starting with the “Check Engine Light,” I connected a scanner and retrieved emission code P0345 (Camshaft Sensor Fault Code). I removed the air intake ducting and traced back the camshaft sensor harness to find a good place to connect my lab scope and test. What I found was the TC connector was plugged into the Camshaft Sensor and the Camshaft Sensor connector was plugged into a TC actuator. This will be easy; I’ll just reverse the communication connection. I started the engine and the TC and emissions warning lights turned off. GREAT. I didn’t even get out of the parking lot before the Anti-Lock Brake System (ABS) warning light turned on. Since the “Check Engine Light” was still off I put the ABS issue on hold also, OR SO I THOUGHT, and continued driving the car to allow the onboard emissions self-evaluation testing to complete. During the drive the “Check Engine Light” came back on. A new code was set indicating a Vehicle Speed Sensor (VSS) fault. Now I have an ABS fault, a TC fault and a VSS fault. The more I fix, the more I need to fix.
The reason for this is when a system fails, the onboard self-evaluation testing for that system is suspended. If not, a failed component could adversely affect testing results and set a false trouble code. Complete system testing may not reoccur until the failures are repaired. If the vehicle continues to be driven without repair, over time other faults can accumulate but may not be known until the original failure is corrected and onboard testing restarts. That’s what I think happened with this car and that’s where I find myself. The VSS fault is an emission fault and is standing in the way of my payday. I need it gone. I can’t find my crystal ball right now so I don’t know where this is headed but with some hard work I won’t need it anyway. The customer is hanging in there very nicely for now. After some research, I determined VSS data is directly related to the ABS wheel speed data. Hey, I have an ABS code also. Is the emission fault and ABS fault related? Yes, as it will turn out. The ABS Module receives data from the wheel speed sensors, uses it and then sends it to all the other modules via the communication network. Some modules like the sun roof or headlamps don’t need speed sensor data and pass it along. Door modules on the other hand use wheel speed data to lock the doors above a certain speed. Other modules like ABS, TC and Powertrain Control Module (PCM – engine) use the data as part of their calculation. Now we are getting somewhere. The wheel speed sensors are the common denominator. This BMW has four, one at each wheel. Here’s how the network works:
The wheel speed sensors generate a speed signal. All four should indicate the same speed at all times. If under hard braking, for example, a wheel speed sensor indicated 0 miles per hour, the ABS Module knows that wheel is locked up and skidding. The ABS module will lower the brake pressure to that wheel until it starts spinning slowly and vehicle control is regained. The TC Module also uses wheel speed sensor data but for a different purpose. During acceleration, if the rear wheels (driving wheels) spin faster than the front wheels, the TC Module activates a component that reduces engine power until the rear and front wheel speed sensors match indicating rear wheel traction is regained. This is especially helpful on icy or slippery surfaces. The Tire Pressure Module (TPM) uses wheel speed data to detect an under-inflated tire. An under-inflated tire has a smaller circumference and therefore spins faster. If this condition occurs the “Low Tire” warning lamp may be turned on. Lastly for our conversation, the PCM uses wheel speed as vehicle speed. The vehicle speed is part of the engine load calculation and is used in determining the fuel injection calculation. Wheel speed sensors are important components that impact many systems. If your doors stop locking as you drive away, better check the brakes.
I decided the best way to solve the “Check Engine Light” problem was to solve the ABS problem. Sure enough, the ABS Module had a right rear speed sensor fault code stored. I went for a test drive to verify. After further testing, the speed sensor was communicating and its information was accurate. The ABS Module failed. My cost from the BMW dealer for a new ABS Module was $1500. WOW!!! I had to replace the ABS Module (BRAKES!) in order for this vehicle to pass a Smog Inspection. I was able to find a good used ABS Module and the car passed its smog inspection easily. All the other related systems are also function correctly and no more warning lamps.
If you Google Complete Car Care Fresno, and click Demand Force Intuit Reviews, you will be able to read this customer’s comments. Look for Anita and Clarence. It feels GOOD to solve a tough one for a customer.
If you have any questions about your vehicle or suggestion for future topics, please give me a shout at email@example.com. Your input would be appreciated. I would like to answer the questions that interest you.
God Bless 93636 and Go Hawks,
EO139887 (Smog License)
California ARD License #117312
(Automotive Repair Dealer License)
Sermon of the Mount
After what happened in the shop this week I decided to write about the exciting world of motor mounts. Just like everything else in the automotive world, today even motor mounts can be controlled by the Powertrain Control Module (PCM).
I’m going to categorize motor mounts into two basic groups: hydraulic and non-hydraulic (elasto-rubber). Before I give a basic explanation of how they work, a short explanation of their purpose is in order. Motors and transmissions (the powertrain) can vibrate when spinning. Inside are large masses of reciprocating and rotating weight. If the heavy powertrains were mounted directly to the vehicle’s frame, the vibrations would radiate through the frame and into you. Also, if the powertrains were solidly mounted, lack of rigidity would eventually crack the frame or powertrain member. Therefore, powertrains are mounted with rubber. The rubber is elastic and stretches and compresses to absorb powertrain vibrations. A traditional motor mount has an upper and lower steel member with a block of solid rubber sandwiched in-between. A hydraulic motor mount is basically the same except the solid rubber block is a rubber bladder filled with hydraulic fluid. The hydraulic mount is generally larger and more expensive. The upper steel member is bolted to a powertrain member and the lower is bolted to the frame.
Hard rubber motor mounts are cheaper but don’t absorb as well. Hydraulic mounts do a much better job but they are less durable. Some problems with the solid rubber types of mounts are, depending on which type, the rubber sandwiched between the two steel members is eventually compressed by the Sermon of the Mount weight of the engine or the heat from the exhaust causes the rubber to harden and lose elasticity. Some rubber motor mounts are designed like suspension bridges. The motor is bolted at the midpoint of the rubber bridge. Over time and loads, the bridge sags and rests on the frame. It’s almost like having no motor mounts at all. The main problem with hydraulic mounts is they tend to crack and leak. As I mention in the beginning of this article, some hydraulic motor mounts are controlled by the engine computer. Honda, for example, has a V6 variable displacement engine that when it’s in “Eco Mode” drops out three cylinders. The motor becomes a three cylinder as the vehicle cruises down the highway. The three remaining cylinders are all in the same bank. This odd fire configuration creates a motor vibration. The PCM creates a counter vibration in the hydraulic motor mount to counter balance the odd fire vibration.
Doesn’t stop there.
The Body Control Module generates a noise that transmits through the radio speakers to cancel the offending exhaust noise. Crazy what engineers design to increase fuel economy. The modern automotive technician has to keep up with it all.
The powertrain members need to be firmly held in place. If not, when putting the vehicle into gear or under hard acceleration the motor will rock. If the powertrain rocks, it can pull the wiring harness apart, break hoses, the cooling fan can strike the fan shroud, output shafts can become misaligned, just to name a few. If you hear a thump during any of those conditions, test the motor mounts.
OK, let’s test. Testing is much cheaper then guessing.
Apply the parking brake. Idle the motor in park and take note of any vibrations. Foot on the brake pedal (vehicle should not move), shift into reverse, then into drive and see if the vibration lessens or disappears. If so, it’s time to replace the motor mounts.
These next tips are what we do. WARNING! I’m NOT telling you to do what we do! If you do this, don’t contact me later and complain I caused you to smash the oil pan or wreck the vehicle. Do this at your own risk. Don’t hesitate to drive to the shop and ask for help. This one is a freebee.
With the motor still idling, we use a floor jack with a large flat piece of wood on the jack pad to distribute the weight of the motor over a large area. We raise the motor just enough (1-3 inches) to take the weight off the motor mounts. The motor weight should be resting on the floor jack. We repeat the diagnostic process above. If the vibration is gone, it’s time to change the motor mounts.
Next, we go to an open space with nothing around to hit. We raise the hood, set the parking brake, place wheel chocks at every wheel and press as hard as we can on the brake pedal. If we have an automatic transmission, we “Power Jack” (step on the brake pedal and gas pedal at the same time) the motor. If you are doing what we do, be careful and start easy. Watch and see if the motor raises. CAUTION, if a motor mount is severely damaged the motor can raise so high it may look like it’s going to leap into your lap. BE EASY, BE CAREFUL. Do the same in reverse and drive so you can load the motor mounts on each side of the engine. The motor should not rise or twist. Also. if during the test you hear a thud, it’s time to change motor mounts. If you drive a manual transmission, it’s much harder to Power Jack. You will have to slip the clutch. This is tough to do. Just try it a couple of times and then rest before trying again. I don’t want you to smoke the clutch assembly.
Changing motor mounts can be a very frustrating job. Lots of tight spaces, reaching around narrow corners, sharp edges and dirty. It’s a real knuckle buster. Don’t snap off any bolts or you will have a very, very bad week. That’s what happened to us. Having a left hander available is very helpful. Lefties have no problem reaching around places backwards to us. I don’t personally replace motor mounts any more, I pass that job off to my staff. I still have the hole in the wall inside my shop from 25 years ago when my wrench flew through the sheet rock and into the wall. Wrench is still there.
Guys, LISTEN UP: if anyone driving the vehicle you intend to replace motor mounts on is annoyed by little things, use the factory original equipment mounts. You don’t want to do this job a second time. If it’s your work truck and you want to save money, after market mounts should be fine. NAPA has a new line of quality motor mounts that have been successful for us. I still will not use anything but original equipment mounts if they are tough to replace. OK, let’s get to replacing. Raise the vehicle as high as you can and put it on four jack stands. Make sure you compare the new mounts to the old ones and make sure they are a match. If not, you can waste a lot of time trying to install a nonmatched look alike part. Don’t force the motor mounts in. They should fit. If you force them, they are in a bind and you will create a new vibration.
The basic idea is to take out only the motor mount bolts on one side of the motor at a time. Do not remove all the mount bolts at the same time. Rotate (jack or lift) the engine up, replace the mount and lower the engine back into place. The side you have not disassembled will hold the powertrain inline. Do the same thing on the other side. When you finish, repeat all the diagnostic tests to confirm the quality of the repair.
OK, good luck. That’s about all from me. If you have questions regarding any vehicle or suggestions for future topics, please email firstname.lastname@example.org.
God Bless 93636 and Go Hawks,
EO139887 (Smog License)
California ARD License #117312 (Automotive
Repair Dealer License)
Tech as Close as Your Phone
I am excited to tell you about a brand new technology for the automotive diagnostics world. You may have this technology in your pocket right now and don’t even realize it. Although it’s not a new technology, the automotive diagnostic application is. I can barely wait to demonstrate this technology to Liberty High School students at the next Career Fair Day. As recently as last fall this automotive diagnostic technology was undiscovered. After reading this article you will be equipped to perform some modern automotive diagnostic tests that most shops are not even aware of. Let me explain.
The modern automotive vehicle is the most complex, complicated, sophisticated piece of technology that you interact with on a daily basis. The vehicle’s electrical system is one of its most complex systems. Today, successful automotive technicians spend many hours per year in training to equip themselves for the task of diagnosing and repairing these modern marvels. Last month I attended another advanced electronics circuit diagnostic class. Dean, my instructor, is the lead diagnostic technician in his father’s automotive repair business in southern California. His shop is very successful and employees 15 technicians. Because of the scope, quality and reliability of their work, many governmental agencies outsource work to him.
As Dean tells the story, he was attempting to diagnosis the infamous dreaded parasitic load complaint when a fireman entered the shop and began watching. A parasitic load generally manifests itself as a dead battery in the morning. The customer usually says something like, “I installed a new battery but I still have to jump start my vehicle every day.” During the course of Dean’s diagnostic routine, the fireman said, “I have something that may help you.” When he returned from his truck he pointed his technology at the power distribution box that Dean was testing and said, “These two fuses have a much higher heat signature that all the others.”
That’s how it happened.
By happenstance a new technology was introduced into the automotive diagnostic world and you are among the first to know. The fireman used a Forward Looking Infrared Camera (FLIR) that he uses to look behind walls to identify a fire’s location and determine if there are individuals trapped inside. The problem for us is his FLIR Camera has a hefty price tag of about $10,000. With a little research, Dean discovered the Samsung 6 and the Samsung 6 GS cell phones already have a FLIR camera installed. Some of the guys in class had these cell phones and uploaded the FLIR App at break. Within a short time, we thought of many potential automotive diagnostic uses for this technology. Maybe we can use this technology to diagnosis a restricted radiator or AC condenser. Currently we use an infrared thermometer for this purpose. On a properly functioning radiator or AC condenser there should be a minimum 30 degree drop in temperature between the inlet and outlet. Now I may be able to point a FLIR camera at these components and see the gradual transition in color. I wonder if I can aim the FLIR camera at a coolant thermostat housing and determine if the engine overheating problem is a stuck closed thermostat? I’m also thinking the FLIR camera might be useful for catalytic converter diagnostics. If a converter is efficiently oxidizing exhaust emissions, the exit temperature will be greater.
I’m certain it can be used to diagnosis vehicle braking problems. If a vehicle drifts during braking, I can use the FLIR image to see if one brake is preforming more work than the others. If a vehicle seems to be blowing through front brakes like a NASCAR stock car at Bristol, maybe the brake master cylinder has failed and the rear brakes are not being applied. The heat signature will tell. As you can see, it’s just physics and the diagnostic potential is endless. Hope this tip helps. At minimum it should be fun for you all to try.
Please contact me at complete_ email@example.com. OK, happy hunting and God Bless.
Smog License #EO139887
Don’t Blame Me
The EPA recently announced that by 2021, all cars and light duty trucks sold in the U.S. must use a Global Warming Potential (GWP) refrigerant below 150. The new refrigerant is designed to reduce CO2 in the earth’s atmosphere and slow global warming according to global warming scientists. The Intergovernmental Panel on Climate Change (IPCC) assigned the new R-1234yf refrigerant a GWP value of “4” while the automotive refrigerant used since 1994 (R-134A) was assigned a GWP value of 1,430.
The EPA’s objective is to have the U.S. vehicle fleet not only equipped with R-1234yf for environmental reasons, but maintained with it as well. The R-1234yf systems have a very low capacity and are equipped with super-sealing connectors to prevent leaking. Loss of just a few ounces can reduce performance noticeably. The R-1234yf systems will contain between 8-16 ounces of refrigerant at $200 per pound to service them.
An EPA spokesperson went on record saying, “If a professional technician knowingly installs R-134A into a R-1234yf system, that would constitute tampering with an emission control system and would be an obvious violation of the law.”
followed allowed other components of the refrigerant to form very toxic substances.
Sometimes the situations we allow ourselves to be forced into to save Mother Earth are just plan ridiculous, potentially hazardous and dangerous. The earth’s atmosphere contains about 78 percent nitrogen, 21 percent oxygen and 1 percent everything else. CO2 is about .036 of the 1 percent of everything else. The CO2 content in the earth’s atmosphere would need to increase by 27 times its present value to become just 1 percent of the earth’s atmosphere. CO2 is what we humans exhale and is absolutely essential for green plants and certain other organisms to synthesize carbohydrates. The byproduct of that process is oxygen. CO2 is NOT a hazardous emission. The modern vehicle primarily exhausts CO2 and H2O vapor.
Climate reconstruction models show concentrations of CO2 in the earth’s atmosphere have varied from about 17.5 times greater than present day amounts 500 million years ago, to about 2.2 times less than present day amounts 2 million years ago. If you are inclined to believe in climate modeling data, the data indicates the earth goes through natural cycles not caused by humans. According to evolution, Australopithecines (Lucy) didn’t appear on earth until about 1/2 million years later.
Since the Industrial Revolution (1740-1860) life expectancy in the United States has changed dramatically from 25 years in the 1800s to 50 years in the 1900s to today’s mean life span of about 75 years. Seems to me the industrial revolutionand advancements in technology since have INCREASED quantity of life by increasing QUALITY of life.
God Bless 93636
Warren Parr, Smog License # EO139,
Diagnosing the RIGHT Way
I would like to take this opportunity to thank the many who visited my Flatlanders Celebration booth and for the many encouraging and supportive comments received concerning this column. It’s nice to know writing this column is not a labor in vain. I actually wondered at times if anyone even reads the article, given so little feedback. Now I know. Thanks again for your kind words of support.
If you were one of the many visitors who stopped by my booth and watched a diagnostic demonstration, you have a general idea of scope waveform analysis. ALL those humps, bumps, dips and squiggly lines displayed on a grid represent changes (electricity, pressure, temperature, etc.) over time in real time. Scope diagnostic has significant advantages over former diagnostic test methods in that the tests are performed LIVE during operating conditions. To increase the odds for a successful diagnostic, it’s important to test under identical conditions in which the failure occurs. If the problem only occurs when the engine is not running and everybody is resting under the shade of the closed hood, then by all means go ahead and go old school. Take the components off one by one and test them on a work bench. If not, the tests should be performed when the engine is running and the components are hot, tired and stressed. Dynamic testing for dynamic failures I always say.
Let’s use electronic fuel injector testing as an example. With today’s engines, the odds that you can even see a fuel injector, let alone the one you want to test, are low. Many fuel injectors live under or inside the intake manifold. If you remove the intake manifold and all the garbage attached just to gain access to test, you are going to be at it for a while so don’t forget your lunch. When you finally do reach the injector, you won’t be able to start and run the engine. You will be limited to static testing. Good luck with that. Oh, don’t forget: You are going to need a new set of intake manifold gaskets, minimal.
With a Lab Scope, the fuel injector component testing is done at the fuel injector fuse. We replace the fuel injector fuse with a loop of copper wire. By the way, my wire loop is fused to protect the circuit. Using this diagnostic method, EVERY fuel injector is tested and ALL at the same time. Now, before the electrons can complete their journey from the battery to the fuel injectors they must first pass through my wire loop. Whenever electrons flow, they produce an electromotive force called current. Current is measure in amps. The greater the flow the greater the current. I simply place a low current amp probe around my wire loop and measure. I also measure the available voltage at either end of my wire loop. Using two channels of my Lab Scope, I display all current and voltage values in parade fashion (two squiggly lines) during running conditions. The last thing I need to do before I start testing is look up the fuel injector resistance value specification.
The only thing I remove was one fuse so I can start and run the engine. Now comes the math: Ohms Law. Resistance = Voltage divided by Current. For example, if my injector resistance specification is 2 ohms, and my available voltage is 14 volts (remember the engine will be running) the current HAS TO BE 7 amps. I know what my waveforms should look like before I even start testing. If I see a current value different then 7 amps, my resistance is NOT 2 ohms. If the current (amperage) is higher, the resistance has to be less than 2 ohms. This condition typically indicates a short across the coil winding or a short to ground. The resistance is lower because the electrons take a short cut and do not pass through the entire injector winding (resistance). If the current is lower, the resistance has to be higher. This condition typically indicates an open or gap in the circuit making it more difficult for the electrons to pass.
A typical electronic fuel injector current waveform looks similar to the outline of a dorsal fin of a shark. The leading edge of the waveform gradually curves into a horizontal position as it reaches its max height. It’s not a straight slanted line, like a motorcycle ramp; it’s rounded. That leading edge represents the building up (ramping) of an electromotive force (magnetism). When the magnetism is strong enough to overcome the fuel pressure, a metal pintle inside the fuel injector is lifted off its seat allowing fuel to pass into the cylinder. This fuel injector opening event is displayed as a dip and then a flattening out of the leading edge ramp. That dip should be located about 2/3 of the way up the ramp. The dip in the waveform not only indicates the injector opened, but when it opened. Too early would create a rich condition. Too late would create a lean condition.
Finally, the trailing edge of the waveform should be a vertical line. This represents the powertrain control module (PCM) de-energizing the fuel injector and stopping fuel flow. This needs to happen rapidly. If the trailing edge is slanted or rounded, the PCM driver is too slow to turn off the fuel injector and the precise quantity of fuel entering the cylinders is incorrect.
In conclusion, old school automotive diagnostics need to go the way of the Dodo Bird. It’s too slow, too inaccurate and too labor intensive. I know when you hear the words diagnostic technology they sound expensive. That is very true if you are the one purchasing the technology. If you are the customer it represents fewer parts being replaced and a higher quality repair.
God Bless 93636
To D.I.Y. or Not to D.I.Y
Hello 93636 and greetings,
This week I attended an Anti-Lock Brake (ABS) update course. The training included the most current diagnostic information and repair procedures for many domestic and foreign vehicles traveling our roadways today. Our instructor is the owner and lead technician of a very successful German automotive repair business in Seattle, Wash. He has 35 plus years of experience, is highly qualified and his classes are in much demand throughout the United States. Unfortunately, there were only about six Central Valley repair shops in attendance. How in the heck are those other shops going to properly diagnosis and repair these ABS systems? The reality is, they won’t.
My shop is the shop of last resort for many. A lot of my new customers are referrals. They have been to several shops prior with no success. I hear these words a lot:
“They ripped me off.”
“They replaced parts I didn’t need.”
“They took my money but didn’t fix my problem.”
Yes, I understand. You have been ripped off but not in the way you think. It is not deliberate and not intentional. The people who worked on your vehicle prior were not qualified. Without proper training and the diagnostic equipment it can become a guessing game. The most expensive diagnostic and repairs are the ones that use the trial and error method.
ASK!!! Make sure you are at an Automotive Service Excellence (ASE) certified shop with ASE certified technicians at a minimum. ASE technicians re-certify every five years so it doesn’t guarantee your chosen facility and technician is qualified. Vehicle complexity increases geometrically annually. It does mean they are somewhat current and meet a basic standard. ASK about their updated and ongoing education and training. We proudly display our training certificates in our customer lounge.
Ok, back to ABS. The ABS System prevents the vehicle’s brakes from locking up and skidding on slippery surfaces and/or during panic stops. This allows you to steer around the object instead of sliding into it. REMEMBER THIS: The ABS may INCREASE stopping distance, so steer AROUND the object. This isn’t bowling so it’s ok to miss. Here’s a basic outline of the process during an ABS action: When the brake pedal is slammed to the floor, hydraulic brake fluid is pressurized by the master cylinder and channeled to each of the vehicle’s four brakes at about 500 pounds per square inch (psi). Each of these channels have an Isolation Valve (normally open) and a Dump Valve (normally closed) controlled by the ABS Module. These valves are essentially gates. When open, fluid flows unrestricted. When closed, fluid flow is blocked. During an ABS event, the module takes control of vehicle braking by closing the Isolation Valves and trapping pressurized brake fluid. You are NOT IN CONTROL – the ABS Module is. If the pressure is too high and a wheel stops spinning (skidding), the Dump Valve is opened to reduce off some of the applied pressure. Once the wheel is spinning again the module closes the Dump Valve trapping the remaining fluid. Ok, how do we re-apply that brake once the applied pressure is reduced? Modern ABS Systems incorporate a high pressure pump and an accumulator or reservoir. When the vehicle’s key is turned to the “Start or Run” position, the high pressure pump fills the accumulator in anticipation of an ABS action. At 2,400 psi the brake fluid flows quicker allowing the ABS Module more precise control. The pressurized fluid in the accumulator (not the master cylinder) is what the module uses to control ABS braking. Pushing the brake pedal harder will not stop the vehicle any sooner. Also, you may feel a pulsation at the brake pedal and/or hear a buzzing noise. It’s not defective; that’s normal.
I like to be proactive. I find a parking lot somewhere where there are no other vehicles so I can safely make a couple of panic stops. The slicker the better. That way I know in advance how my vehicle will react during an ABS event.
Ok 93636 “Do It Yourselfers,” here’s the primary reason for this article: ABS accumulators are discharged at some point after the key is turned off. Some vehicles discharge their accumulators while performing a brake system check. These types of ABS Modules use an accumulator high pressure fluid to apply the brakes, perform a pressure test, then reduce the applied pressure by opening the dump valve. Do-It-Yourselfers, did you get that? Your vehicle can apply its brakes all by itself! What happens if the “Brake Self Test” occurs while you are changing the brake pads? BIG BIG PROBLEMS. It happens and it’s dangerous. Some vehicles require the use of a scan tool to place the ABS in “Stand Down Mode” prior to any brake service. If you don’t have the scan tool – STOP!
Now, this is where this article should end. I know however there are many risk takers, like me, that won’t let a little danger stop us. It gets our blood circulating. If you insist on continuing in spite of the danger, let me tell you what I would do if my scan tool would not “Stand Down” an ABS. I am NOT ADVISING ANYONE TO USE THIS PROCEEDURE! I’m telling you what I would do to decrease my risk.
I would remove ALL ABS fuses and attempt to “power down” the module. If I could not find ALL the ABS fuses or I was not sure, I would disconnect the vehicle’s battery, knowing all the learned adaptive values might be lost and I may need to drive the vehicle for a while in order for it to relearn and run well again. If your ABS Module type uses capacitors (stores voltage) as a backup power system, after removing the battery cables from the battery I would touch the positive and negative battery cables TOGETHER, for at least five minutes to discharge any capacitors.
DO NOT TOUCH THE CABLES TOGETHER WHILE THEY ARE CONNECTED TO THE BATTERY!
That mistake could destroy the vehicle’s electronics.
Do-It-Yourselfers, no disrespect, but there are some vehicle repairs that untrained and unqualified persons should not attempt. Brake systems are now one of those repairs. In my opinion not all automotive repair shops are qualified either. Be careful, use your brain and do your homework.
If you have any general or specific vehicle questions or suggestions for future topics, contact me at firstname.lastname@example.org or leave a message at the Complete Car Care Facebook page.
God Bless America and God Bless
ARD License # 117312
Emissions Inspector Lic. #EO139887
How to Keep Cool
Just a few tips to help you “do-ityourselfers” understand and properly diagnosis your vehicle’s cooling system. In this hot weather it may just come in handy.
Let’s start by checking and servicing your vehicle’s cooling system. If you drive a Toyota Prius or newer Ford diesel pickup, you have two separate and independent cooling systems. Check both. In the case of the Prius, one cooling system is for the gasoline engine and the second is for the hybrid high voltage electrical system.
If your vehicle has a radiator with a radiator cap, check the coolant level there. You should be able to visually see the coolant inside the radiator neck. The color of the coolant will differ depending on the type of coolant and vehicle manufacture. Turn the radiator cap over and inspect the large and small rubber seals for cracks. Replace the cap if any are found. For safety, only check the coolant level when the engine is cool.
If the cooling system is low, top it off. Use coolant, not water. Some beneficial properties of coolant over water are: It raises the boiling point; lowers the freezing point; inhibits rust and; lubricates the water pump. DO NOT use one size fits all coolant. Use only the coolant designed specifically for your vehicle. If you cross-mix coolants, they can create a gel. When that happens you have big problems. BE CAREFUL! There should be a manufacturer’s coolant information label somewhere under the hood. Use it. If not, get the owner’s manual from the glove box. If you don’t know which coolant to use or the proper coolant is not available, use distilled water. Do not use tap water if possible. We don’t want an adverse chemical reaction from fluoride, chlorine or whatever else is in the tap water and I certainly don’t want particles of iron circulating throughout the cooling system and grinding on things like plastic water pump impellers. By the way, the cooling system service intervals are listed on the label and in the owner’s manual. Service the cooling system on time. Coolant does wear out.
Many vehicles have cooling sys tems with the fill cap mounted on top of the expansion tank. If you inspect the expansion tank, you will see a cold and warm full mark. If the engine is warm, the coolant level in the expansion tank should be at the upper mark or warm level. In the morning when the coolant is cool, the coolant level should be at the lower mark, NOT THE TOP ONE. I don’t trust these systems to accurately display the correct coolant level. Look inside the radiator whenever possible. Here’s my explanation: When coolant temperature increases, the coolant expands into the expansion tank. When coolant temperature decreases and the coolant contracts, a vacuum is created in the cooling system drawing coolant out of the expansion tank and back into the cooling system. The radiator is ALWAYS FULL, hot or cold. But if the cooling system has a leak (not sealed), the expansion tank can lie. Outside air can be sucked into the cooling system instead of coolant from the tank. The unintended consequences are an air pocket in the cooling system and the expansion tank will always show full (TOP MARK) even if the system is cool and/or the Radiator is empty. If you verify the expansion tank level is active, then – and only then – can it be a trusted coolant level indicator.
Some other indicators of a low cooling system are the heater does not blow hot air. There may not be enough coolant to circulate through the heater core. Also, the coolant temperature gauge on the dash is fluctuating. It should be rock solid. If the gauge is fluctuating it is an indication of air pockets passing by the coolant temperature sensor. If the cooling system is consistently low, have it pressure checked for leaks.
Here’s some more overheating diagnostic tips I’ve learned over the years: If your vehicle overheats only when the vehicle is stopped or in stop and go traffic, suspect the radiator cooling fan is inactive. When traveling down the road the cooling system is not dependent on the cooling fan because air is being rammed through the radiator from the motion of the vehicle. When the vehicle stops, the rammed air also stops and the cooling system becomes dependent on the cooling fan. If the fan is inactive, overheating.
DIAGNOSTIC TIP #1: Get out and see if your cooling fan is spinning. Next, place a hand towel over the vehicle’s grille. If the fan is efficient, it will suck enough air through the grille to pin the towel. Next, turn the engine off and see that the towel does fall off. If the towel was not pinned, I start my diagnosis with the cooling system fan.
Here’s another useful tip: If you have air conditioning, turn it on. Most vehicles automatically turn on the radiator fans when the AC is on. If the overheating condition disappears, suspect a failed engine cooling fan temperature indicator switch.
DIAGNOSTIC TIP #2: If the vehicle always overheats, happens within a few miles and the cooling system is full, suspect a stuck closed thermostat or head gasket failure. Unless the vehicle has been severely overheated within the last several months, the odds are in your favor it’s not a head gasket failure. If your cell phone has a forward-looking infrared app, sample the coolant temperature in front and back of the thermostat. If the thermostat is open the temperatures will be identical.
DIAGNOSTIC TIP #3: If the vehicle only overheats at higher speeds and/or climbing hills, suspect a restricted radiator or soft lower radiator hose. At lessor engine speeds, the engine generates less heat and the water pump turns slower. When the engine begins working harder it speeds up. As a result, more heat is generated and the water pump spins faster. If the radiator is internally restricted, not enough coolant can be circulated through the radiator to remove the increased heat. Also, if the lower hose becomes soft, the increased suction from the water pump can collapse it.
DIAGNOSTIC TIP #4: If the engine runs slightly warmer and the AC air is also warmer, wash the AC condenser and radiator by spraying water through the grille to remove dust and bugs.
Hope this helps. Give me a call if you need clarification or have additional questions.
If you have suggestions for future topics, as always I can be reached at email@example.com or Facebook. I would love to answer your questions.
God Bless America and God Bless 93636
EO License # 139887
The HC Detective
Today’s topic is technology. The modern automobile is the most complex piece of technology that most individuals interact with on a daily basis. Modern vehicles can have up to 60 modules (computers) on board communicating on several networks and can communicate with other vehicles in close proximity. For example, if a vehicle drives over a slippery spot in the roadway and the Traction Control Feature is activated, that information is relayed to other vehicles in the area to alert them of the potential danger. Drivers are unaware of vehicle to vehicle communication and the actions taken to keep them safe.
The technology I would like to discuss today however is the technology we use daily to diagnosis and repair these marvels of modern engineering. Since all vehicles are products of math and engineering, all vehicle failures and their solutions are math and science problems. My company motto is: “Quality, Dependability and Performance through Science and Technology.”
Today I would like to discuss the Five Gas Analyzer. The probe you observe in a tailpipe during an emission test is attached to the analyzer. The analyzer samples and displays the values of the five tailpipe gases in percentages or parts per million (PPM). Understanding the relationships between gases – how and why they are formed – diagnostically tells us nearly everything we need to know to start our diagnostic in the proper direction. Collecting and entering those gas values into a Lambda Calculator is diagnostic on steroids when evaluating the fuel injection, secondary ignition and the efficiency of the Catalytic Converter and combustion process. The Five Gas Analyzer is INDISPENSABLE for the proper diagnosis of emissions and drivability problems.
Today’s primary topic is the untraditional and innovative ways we use five gas technology to advance diagnostics outside of emissions. One of our largest competitors sends us a lot of referrals. When they suspect a blown head gasket or cracked cylinder head they perform the traditional “Block Test.” If the vehicle fails the test the customer is referred to us. Their diagnosis has a high rate of inaccuracy, much to the relief of those customers. We use our Five Gas Analyzer. When a head gasket loses its seal or the cylinder head is cracked, the gasoline/hydrocarbon (HC) vapor in that cylinder is leaked into the cooling system during the compression event. Those air bubbles collect at the highest point in the cooling system: the radiator neck. With the radiator cap removed, we sample that gas. If HCs are present, we have a sealing problem. It’s quick and accurate.
Another untraditional way we use this technology is when customers complain of gasoline fumes in or around the vehicle. I move the emission probe over the engine, down the fuel rails and fuel supply lines, on top of the fuel tank and over the vapor canister while watching the analyzer monitor. Once HCs are displayed, I just keep working the probe until I find the highest concentration. I do not have to smell the leak in order to find it. The five gas technology puts me on the complaint quickly and accurately.
Last week I was battling a 1994 Nissan Maxima with a misfire. My diagnostic lead me to believe I was dealing with a defective fuel injector. The problem was my fuel injector was under the intake manifold and labor intensive. I wanted to be reasonably sure the misfire cause is insufficient fuel before I invest that much time. I removed the spark plug and inserted the emission probe. I started the engine and monitored the HCs. Only 35 PPMs displayed. A good injector will display HCs in the 5,000 PPM range and above. A new fuel injector solved the problem and the Maxima easily passed its smog inspection.
Automotive repair is not a stagnant industry. We continue to learn, innovate and advance our diagnostic capabilities to keep up with the advancements in Automotive technology.
OK. That’s all for today. As usual I can be reached for suggestions for future topics or specific questions concerning your vehicle at firstname.lastname@example.org or Facebook. God Bless 93636 and God Bless America.
EO License # 139887
I want to again thank the many of you who have come by the shop to check us out and personally say hi. I also want to thank the many more who visited us on Facebook. Thank you 93636 for all your support.
I chose this article’s topic because I believe it is interesting, informative and enlightening. This type of vehicle may soon be parked in your driveway, if not already. I also want to give the 93636 “Do-it-Yourselfers” crowd a heads up so they avoid the mistake we made with our first replacement of an electric power steering unit.
Three weeks ago a 2010 Ford Fusion came into the shop with a “no power steering” complaint. The steering was electric so we connected a scanner and retrieved trouble codes to begin the diagnostic process. The electric steering gear was defective so we recommended replacement. The steering gear is a rack and pinion type. We did our due diligence and all the information we generated indicated the replacement unit was a “Plug and Play;” just bolt it in and go. The defective gear assembly came out and the replacement was installed without incident, or so we thought.
The new gear didn’t work.
Again we began diagnostic only to find the new steering gear needed to be programmed. If that information would have been available to us in the beginning, we would have removed the memory from the failed unit while it was still in the vehicle and connected to the vehicle’s network. The defective unit is now laying on the shop floor. We have to reprogram the whole darn car. No problem. After the programing everything worked fine, it just took several hours more then it needed to.
“Do-it-Yourselfers,” again I’m sorry to say, it’s very unlikely that you will be able to complete this repair by yourself. If you are going to give it a try anyway, make sure the memory is extracted BEFORE you remove the steering gear or it will increase your time and be expensive. Don’t feel bad though – heck, I only know of a hand ful of independent shops that can handle this repair.
Let’s discuss the advantage of electric steering. Hydraulic steering uses a hydraulic pump to deliver pressurized fluid to the steering gear to decrease steering effort. The pump is driven by a belt connected to the gasoline engine. As long as the gasoline engine is running there is a power steering pump load on the engine, even if you are driving straight ahead. Motorized electric steering only creates a load when turning. Soon most gasoline engine loads will be transferred to small electric motors controlled by the PCM (computer), not just the steering. In addition, the systems operated by electric motors will continue to operate even when your vehicle’s engine is turned off during a stop. YES, that’s right, soon your vehicle’s engine will stop running (stall) when coming to a stop. The gasoline engine will automatically restart when you depress the gas pedal to drive away. I’ll bet some of you are thinking this will create a lot of wear and tear and increase failure rates for batteries and starter motors. There are a lot of variations but the concept is the same. Your vehicle will use a much larger battery and starter motor. The starter motor is massive and in many cases doubles as the vehicle’s alternator. It will recharge the batteries while the gasoline engine is running and restart the gasoline engine when it’s off. The larger battery will also facilitate higher voltages. The increased voltage output will increase starter speed by more than seven times. The gasoline engine starts immediately when you depress the gas pedal to drive away.
The air conditioning compressor and the power brake booster will no longer be directly connected to the gasoline engine. Both systems will be powered by electric motors and continue to function when the gasoline engine is turned off during a stopping event. You will need that BIG battery while you are waiting for that train that is parked on the tracks, during a summer evening, while the air conditioning is running, the radio or entertainment system is playing and the headlights and brake lights are on.
About two years ago I worked on a Karma Fisker. These automobiles do not use transmissions. The gasoline engine powers a generator which powers two electric traction motors in the rear differential housing. It’s very possible in the near future transmissions will become obsolete just like carburetors.
The primary reason for the addition of electric motors is they are more energy efficient than gasoline engines and thereby improve fuel mileage and decrease emissions.
It’s my hope to bring Career Vocational Education classes to Golden Valley Unified School District. When we build the curriculum it would be my preference that it be forward-thinking and innovative, not repackaged Vocational Education from the past. As always, I’m looking for ideas to write about. If you have suggestions or have a question about a vehicle, please contact me at email@example.com or the Complete Car Care Facebook page.
God Bless America and God Bless
Two-time ASE/NAPA California Technician of the Year
2013 ASE/NAPA National Technician of the Year 2nd Runner Up
ASE Certified Master and Advance Level (L1) Technician
Don’t Anti-Seize the Day
Two weeks ago, I had a 2000 Jeep Wrangler with a 4.0L engine come into the shop with misfire codes. When I walked out to greet my new customer I could hear his Jeep running poorly. Joe was referred to us by a “Big Box” automotive repair chain. After questioning Joe, I raised the Jeep’s hood to investigate. I saw lots of expensive new parts so I knew there was more to this story.
He told me the “Check Engine” lamp was on before he went to a corner Quick Lube Station to have his oil changed. While the Jeep was being serviced, the service advisor retrieved trouble codes P0301 (misfire cylinder #1) and P0302 (misfire cylinder #2). After some discussion, Joe decided to have the corner Quick Lube Station replace his spark plugs. After the work was completed there was no improvement in the Jeep’s performance and the “Check Engine” lamp returned. Now, instead of trouble codes P0301 and P0302, P0304 (misfire cylinder #4) and P0306 (misfire cylinder #6) replaced them. The corner Quick Lube Station threw all those new parts at the Jeep but they could not solve the problem. I have told you guys many times, the most expensive diagnostic strategy is replacing good parts with new parts. The most cost efficient diagnostic strategy is testing and replacement of only the defective part(s). Several other shops attempted to fix this Jeep but also were unable to solve the mystery misfires.
Before I ran my normal diagnostic routine, I searched Jeep’s Technical Service Bulletin (TSB) library hoping to narrow my search. I discovered a TSB that matched the symptoms of Joe’s Wrangler. The TSB talked about carbon buildup on the engine’s valve stems and especially if the vehicle is not warmed up properly before driving and/or if the Jeep is mainly driven around town. The carbon buildup causes improper closing (sticking) of the valves.
I decided to remove the spark plugs so I could send a camera through the spark plug hole into the engine to verify carbon build up. As it turned out I didn’t need the camera. The corner Quick Lube Station exacerbated the original problem by adding anti-seize compound to the spark plug treads when they installed the new ones.
Do it Yourselfers: When you do a tune up and replace your spark plugs, put them in dry. NO ANTI-SEIZE!!!
Anti-seize on spark plug threads creates resistance in the secondary ignition (high voltage) ground path. The high resistance restricts the flow of electrons to ground. Instead of 15,000 volts jumping across the spark plug gap on their way to ground, maybe only 4,000 volts make it across. That’s not enough voltage to convert ALL the fuel in the cylinder into pressure. By the way, the secondary ignition voltage that does not jump the spark plug gap finds an alternate path to ground. That can also cause misfires.
Make sure you install your new spark plugs when the engine is at ambient temperature and torque them. If the engine is warm, the metal is expanded and it’s easier to overtighten the spark plugs. When the engine cools down, metal contracts and the spark plugs can become too tight and seize. Anti-seize may reduce seizing but it certainly is a hindrance to secondary ignition performance. Also, if you are going to save money by doing it yourself, make sure you use the manufacturer’s original spark plugs only. It doesn’t matter how well you do your job if you use inferior parts. The quality of your service or repair is NO BETTER than the parts you use, PERIOD. Make sure you check that the spark plug gap is set to the specification on your vehicle’s emission label which is usually located on the hood or fan shroud area.
Once my secondary ignition grounds were clean it was time to find the original cause. Since I had the spark plugs out I installed a pressure transducer into the cylinder #1 spark plug hole. When I cranked the engine over the compression waveform showed a variation in compression by up to 30 percent from compression stroke to compression stroke. That’s the smoking gun I was looking for. I’m now convinced the valves are sticking as Jeep’s TSB indicated.
I followed Jeep’s TSB recommendation and performed a fuel system cleaning. Before I completed the BG Fuel Injection System service, the engine was purring like a kitten. Because of Joe’s driving style I recommended the use of a can of “44K” in the fuel tank every six months or so. I’m not a big fan of “mechanic in the bottle” stuff, but BG Systems has some very powerful additives that work well.
OK everyone, I hope this helps.
It’s gratifying to know that so many of you recognize my name and read this column. What ISN’T so gratifying is that EVERYONE seems to think my NAPA Auto Care Center is located in the Madera Ranchos. Complete Car Care is located in Fresno, three miles south of the San Joaquin River on the 99 freeway. I am located on the east side of the freeway across from Island Water Park. We are the closest official NAPA Auto Care Center to the Madera Ranchos, just a short 15-minute drive.
As always I’m looking for ideas to write about. If you have specific or general questions about your vehicle or the automotive industry, give me a shout at firstname.lastname@example.org or on Facebook at Complete Car Care.
God Bless America and God Bless 93636,
Two-time California NAPA/ASC
Technician of the Year
2013 National NAPA/ASC Technician
of the Year Second Runner Up
Don’t Fail Your Water Pump
I chose today’s topic due to the rash of failed water pumps I replaced this month. These water pump failures were predictable and preventable because the primary cause was low coolant levels.
At my shop, whenever an engine oil change is performed we also perform a large vehicle preventative maintenance inspection. That includes cooling system testing. If the vehicle’s coolant level is low, it indicates a leak. Some customers choose not to repair cooling systems leaks as long as the engine is not overheating. Instead, they choose to top off the cooling system from time to time. In my professional opinion, that’s a bad decision. Sooner or later the leak will need to be repaired. Many times it’s later, when the water pump fails. That’s what happened with the three water pumps I have replaced so far this month.
The vehicle that prompted this article is a 1993 Mitsubishi pick up. The upper radiator tank has been cracked and leaking for some time but the customer adopted the top off from time to time strategy. Yesterday when I saw the Mitsubishi on the flat bed of the tow truck I knew it probably wasn’t good. When the water pump failed, it also took out the belt. Hope he caught it before the engine overheated and damaged the cylinder head gasket. We will see tomorrow. Cooling system leaks can lead to catastrophic engine failures. The proper time to repair a cooling system leak is before. Now, instead of just a radiator repair, I need to replace the water pump and belt. Oh, almost forgot, the water pump on this vehicle is under the timing cover which means the timing belt is likely in the way. WOW. I see a longawaited vacation in my near future.
Here’s my explanation of how water pump failure is caused from LOW (not empty) coolant levels. The water pump impeller moves coolant through the engine block, cylinder head and back into the radiator where the heat is dissipated. The impeller draws fresh, cool coolant from the radiator into the water pump, compresses it and pushes it out the other side into the engine block. When the water pump impeller is not submerged, it mixes air bubbles into the coolant resulting in foaming and cavitation. Waves in the ocean kind of do the same thing as the wave curls over and traps air into the ocean water creating the white foam. The illustration I like to use with my customers to explain cavitation is imagine a large ship riding high in the water with its propeller partially submerged. As the propeller blade rotates it smashes into the water pulverizing and aerating it. The consequence of this action is cavitation. When cavitation happens, a heavy vibration occurs when the air bubbles burst and then again when the blade slaps the water. Same thing happens when the water pump impeller vanes are partially submerged. The vibrations on the impeller are transferred through the impeller shaft, destroying the water pump bearing. Once the bearing fails the pump shaft no longer spins true and the shaft seal begins to leak. Also, worn out coolant also allows bubbles to form on cast aluminum housings and create pits, or cavities, when they explode.
I recommend pulling the owner’s manual from the vehicle’s glove box and read the manufacturer’s recommended service intervals. Engine coolant does wear out. Exchanging coolant at the recommended interval does reduce premature failures of the cooling system. Just a footnote here: If you haven’t noticed, the lower radiator hose is larger than the upper radiator hose because it’s on the suction side (negative pressure) of the water pump and suction is less efficient. The upper radiator hose is smaller in diameter because it’s on the discharge or positive pressure side of the water pump. Whenever a radiator hose blows apart, it’s the upper hose because it’s the one with positive pressure.
For suggestions on future topics or questions concerning a vehicle, I can be contacted at email@example.com or Facebook me at Complete Car Care.
Hope this helps. Happy Thanks giving all. God Bless America and God Bless 93636.
Twice NAPA/ASC California Technician
of the Year
2013 NAPA/ASC National Technician
of the Year, Second Runner Up.
The Injection Section
When I began my professional automotive career in 1985, carburetors were the predominate fuel delivery systems of the day. BMW, Mercedes and some other automotive manufactures did have some fuel injected vehicles in production but they were primarily mechanical fuel injection. As “CAFE” (Corporate Average Fuel Economy) standards increased in the U.S., pressure for improved fuel mileage also increased, making way for the modern computer-controlled fuel injection vehicles.
One of the earliest electronic fuel injection designs was the throttle body system. It looked like a carburetor bolted on top of the intake manifold with wires connected. Fuel was sprayed into the intake manifold plenum where it was mixed with air and waited for an intake valve to open. These systems operated at very low fuel pressures (10-13 p.s.i.). They worked well but weren’t much more fuel efficient then their predecessor, the carburetor. Throttle body was followed by the early generations of port fuel injection. These systems incorporated a fuel injector for every cylinder, relocated the injector to the bottom of the intake manifold runners and the fuel pressure was increased to a whopping 30-40 p.s.i. The first generations of port fuel injection did not control the fuel injectors individually. They were controlled by the computer in pairs or sets called “Gangs.” Better still, but port fuel injection would eventually evolve into sequential fuel injection. With sequential fuel injection, each fuel injector is controlled individually and the fuel is directed at the intake valve at 60 p.s.i. just prior to its opening.
The newest version of gasoline fuel injection is gasoline direct injection. GDI engines are the fastest growing segment of the modern gasoline engine market. Seventy-five percent of vehicles sold in America are now GDI vehicles. GDI incorporates a high-pressure plunger type fuel pump driven by an additional lobe on the camshaft. Fuel pressures reach 3,000 p.s.i.
GDI engines come in two basic fla vors: traditional solenoid-type fuel injectors and piezo electric-type fuel injectors. The traditional solenoid-type injector is an electromagnet. When electrical current passes through the coil of wire inside the fuel injector, it creates a magnetic field. The magnetic field attracts the metal valve inside the injector upward allowing gasoline to pass on through. Because GDI operates at much higher fuel pressures, a stronger magnetic force is required to lift the valve. GDI solenoid fuel injectors operate at voltages ranging from 60-100 volts.
GDI piezo fuel injectors are a completely different animal. Piezo injectors use hundreds of thinly sliced crystal wafers stacked on top of each other. When a crystal wafer is subjected to an electrical shock, it expands and remains in that condition until it’s shocked again. A single wafer expands little but hundreds stacked on top of each other expand enough to open the injector. Piezo injectors operate at voltages as high as 450 volts. The higher voltages increase the opening and closing speeds of the Piezo injectors allowing up to five injections per ignition event.
GDI systems do not mix gasoline and air in the intake manifold. They are separated until just prior to ignition. When the intake valve opens, the air entering the cylinder is swirled around in an outer ring. The fuel injector is positioned in the cylinder head so the gasoline is directed at a ramp machined into the top of the piston. The ramp concentrates and redirects the gasoline upward directly under the spark plug in the center of the ring. If you could see inside the cylinder it would look like a donut. The hole in the middle is the pocket of concentrated gasoline. The outer ring is primarily air. When the pocket of gasoline is ignited, a chain reaction begins. The initial pocket of fuel is just enough to start the flame front and is rapidly followed by a series of additional injection events adding just enough gasoline to keep the flame front moving. As the flame front travels outward it ignites the oxygen in the outer ring. This process requires a much lower air/fuel ratio and thereby increases fuel mileage and power.
Unfortunately, GDI systems have some serious draw backs. GDI technology increases fuel mileage but it also increases maintenance costs. Because GDI systems do not spray gasoline into the intake manifolds, the detergents in the gasoline never comes into contact with the manifold side of the intake valves and oil deposits on top of the valve are not washed away. The oil deposits are baked onto the valve surfaces creating carbon build up. Once a sufficient amount of carbon is accumulated on the back side of the intake valve, the air entering the cylinder tumbles instead of swirls. This disrupts the donut pattern in the cylinder and the ignition sequence is compromised. The malfunction indicator lamp in the dash will illuminate and a misfire code P0300 will be set.
At this time the only way to remove the internal carbon deposits is to disassemble the engine and blast the carbon off using walnut shells. This process is obviously time consuming and costly. There are a couple of proactive ideas being circulated that may be helpful. One idea says switching to synthetic oil helps. Regular motor oil is derived from petroleum-based chemical compounds including hydrocarbons. Eliminating carbon from your oil sounds like a good strategy to me.
The second idea suggests an addition to our routine maintenance schedules. Periodically a chemical should be sprayed into the intake manifold reducing carbon deposits before they have time to accumulate. I’m not sure about the second. It’s possible the chemical may destroy the catalytic converters. In that case the cure is worse than the disease. I know many of us have these vehicles parked in our driveways so as more information becomes available I’ll be sure to pass it on.
As always, I am looking for future topics. If you have any suggestions or questions concerning a vehicle, I can be contacted at firstname.lastname@example.org or Facebook me at Complete Car Care.
Please have a Merry CHRISTmas and a happy and prosperous New Year.
God Bless America and God Bless 93636,