update on my Engine issue/misfire. ecu tuner/sponsors please help
07-30-2009, 06:11 PM
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white and whiter
update on my Engine issue/misfire. ecu tuner/sponsors please help
I'll skip the previous story.
there was compression lost on #4 cylinder (misfire). valve, springs, and rocker arm was replaced. the cam lobe is measured to be fine and everything is put back together. compression test is now normal and still misfires.
injector is fine and working like it should (swap tested all normal), but upon starting the car the #4 will spray for about 8 second and CEL will come on and shut off the fuel. all sparks are normal. test was also done with header back removed to make sure it wasn't the primary cat as well.
this leaves me the only thing left....TIMING.
my question: could ECU get stuck in a loop that it's believing the #4 is still misfiring and shutting down after everything is fixed?
there was compression lost on #4 cylinder (misfire). valve, springs, and rocker arm was replaced. the cam lobe is measured to be fine and everything is put back together. compression test is now normal and still misfires.
injector is fine and working like it should (swap tested all normal), but upon starting the car the #4 will spray for about 8 second and CEL will come on and shut off the fuel. all sparks are normal. test was also done with header back removed to make sure it wasn't the primary cat as well.
this leaves me the only thing left....TIMING.
my question: could ECU get stuck in a loop that it's believing the #4 is still misfiring and shutting down after everything is fixed?
07-30-2009, 09:31 PM
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2002 C32 AMG, 2013 GLK 350/4, 2015 E63S AMG Wagon
Maybe Jerry from LET can answer your question. I have never seen the ECU code, but I have been writing code for a living since 1983. Anything is possible but I don't think it is likely. If you cleared the codes using STAR, then any working memory should be cleared. It is possible that some info (a predefined number of occurrences) is recorded in some version of the event log, but is not used for anything other than a log record.
If the assumption is that timing is set for a bank of cylinders, the fact that only #4 is misfiring, but 5 and 6 are fine tells me its the cams. I may be wrong but all I know is that I was in the same boat with taking my engine apart several times until I replaced my cams.
If the assumption is that timing is set for a bank of cylinders, the fact that only #4 is misfiring, but 5 and 6 are fine tells me its the cams. I may be wrong but all I know is that I was in the same boat with taking my engine apart several times until I replaced my cams.
07-30-2009, 09:43 PM
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Maybe Jerry from LET can answer your question. I have never seen the ECU code, but I have been writing code for a living since 1983. Anything is possible but I don't think it is likely. If you cleared the codes using STAR, then any working memory should be cleared. It is possible that some info (a predefined number of occurrences) is recorded in some version of the event log, but is not used for anything other than a log record.
If the assumption is that timing is set for a bank of cylinders, the fact that only #4 is misfiring, but 5 and 6 are fine tells me its the cams. I may be wrong but all I know is that I was in the same boat with taking my engine apart several times until I replaced my cams.
If the assumption is that timing is set for a bank of cylinders, the fact that only #4 is misfiring, but 5 and 6 are fine tells me its the cams. I may be wrong but all I know is that I was in the same boat with taking my engine apart several times until I replaced my cams.
Cams would be my next route as well...as im sure you have checked the basics like plugs/wires/coilpacks
07-31-2009, 02:43 AM
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white and whiter
f- I want to agree that it's the cam, but the shop did say they have measure the cam and it seems to be within spec. 
I'm gonna have the tune revert back to stock first and see what happens.
I'm gonna have the tune revert back to stock first and see what happens.
Last edited by FrankW; 07-31-2009 at 03:22 AM.
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07-31-2009, 05:09 AM
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Like Jake said I'm sure you checked the plugs, wires, and coil packs. I had a misfire issue on my car. The coil pack's power supply wires have small clips. They just seem to brake off when they get older and you mess with them when doing a plug change or what not.
If the clips that provide the power to the coil packs brakes off over time they can work them selfs out far enough to cause a misfire. The misfire will only happen on the cylinder that has the bad connection.
I'm not saying this is what is happening in your case, but covering all your bases cant hurt. So maybe try unplugging the cylinder in question and then replugging it back in.
I also believe you can clear the fault codes (If you have any) from disconnecting the battery for a while.
If the clips that provide the power to the coil packs brakes off over time they can work them selfs out far enough to cause a misfire. The misfire will only happen on the cylinder that has the bad connection.
I'm not saying this is what is happening in your case, but covering all your bases cant hurt. So maybe try unplugging the cylinder in question and then replugging it back in.
I also believe you can clear the fault codes (If you have any) from disconnecting the battery for a while.
07-31-2009, 08:37 AM
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Like Jake said I'm sure you checked the plugs, wires, and coil packs. I had a misfire issue on my car. The coil pack's power supply wires have small clips. They just seem to brake off when they get older and you mess with them when doing a plug change or what not.
If the clips that provide the power to the coil packs brakes off over time they can work them selfs out far enough to cause a misfire. The misfire will only happen on the cylinder that has the bad connection.
I'm not saying this is what is happening in your case, but covering all your bases cant hurt. So maybe try unplugging the cylinder in question and then replugging it back in.
I also believe you can clear the fault codes (If you have any) from disconnecting the battery for a while.
If the clips that provide the power to the coil packs brakes off over time they can work them selfs out far enough to cause a misfire. The misfire will only happen on the cylinder that has the bad connection.
I'm not saying this is what is happening in your case, but covering all your bases cant hurt. So maybe try unplugging the cylinder in question and then replugging it back in.
I also believe you can clear the fault codes (If you have any) from disconnecting the battery for a while.
Good idea, also change the coil packs and wires/plugs around and see if the issue moves with it. (im sure you have tried that)
We have all had misfires, you will get it fixed...no worries...
I would tend to lean away from the ecu being the culprit. Can you post what you have tried so far, so we can add other ideas for ya.
07-31-2009, 09:43 AM
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I read this entire thread and then I spoke with our software writer. He has never seen an ECU do this either, and feels that there is probably a hardware issue that has not been found.
Who wrote the performance software for this car?
Who wrote the performance software for this car?
07-31-2009, 10:45 AM
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If you had the cam lobes checked you had to take the coil pack off. That kinda makes me think it may not be a loose connection. Maybe be a shot in the dark, but try switching the coil pack on cylinder 4 to the other side of the motor and see if any chance happens.
I dont deal with software but a misfire due to to much ignition or timing in the map would effect more than one cylinder. I dont think when mapping these cars you can add or subtract fueling and spark info to only a single cylinder.
With that said. If the map is more aggressive over stock. There is a possibility its exploiting a weakness in the hardware
Now to add to my last post:
with a loose wire it may feel like the car is running fine at idol. As soon as you raise the RPM's that when a misfire happens. I'm very interested to hear what the problem turns out to be.
I'm confident you will find it. We are all pulling for you to be kicking your self in the pants. When you are relieved to find out its something not to major.
I dont deal with software but a misfire due to to much ignition or timing in the map would effect more than one cylinder. I dont think when mapping these cars you can add or subtract fueling and spark info to only a single cylinder.
With that said. If the map is more aggressive over stock. There is a possibility its exploiting a weakness in the hardware
Now to add to my last post:
with a loose wire it may feel like the car is running fine at idol. As soon as you raise the RPM's that when a misfire happens. I'm very interested to hear what the problem turns out to be.
I'm confident you will find it. We are all pulling for you to be kicking your self in the pants. When you are relieved to find out its something not to major.
07-31-2009, 05:05 PM
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white and whiter
If you had the cam lobes checked you had to take the coil pack off. That kinda makes me think it may not be a loose connection. Maybe be a shot in the dark, but try switching the coil pack on cylinder 4 to the other side of the motor and see if any chance happens.
I dont deal with software but a misfire due to to much ignition or timing in the map would effect more than one cylinder. I dont think when mapping these cars you can add or subtract fueling and spark info to only a single cylinder.
With that said. If the map is more aggressive over stock. There is a possibility its exploiting a weakness in the hardware
Now to add to my last post:
with a loose wire it may feel like the car is running fine at idol. As soon as you raise the RPM's that when a misfire happens. I'm very interested to hear what the problem turns out to be.
I'm confident you will find it. We are all pulling for you to be kicking your self in the pants. When you are relieved to find out its something not to major.
I dont deal with software but a misfire due to to much ignition or timing in the map would effect more than one cylinder. I dont think when mapping these cars you can add or subtract fueling and spark info to only a single cylinder.
With that said. If the map is more aggressive over stock. There is a possibility its exploiting a weakness in the hardware
Now to add to my last post:
with a loose wire it may feel like the car is running fine at idol. As soon as you raise the RPM's that when a misfire happens. I'm very interested to hear what the problem turns out to be.
I'm confident you will find it. We are all pulling for you to be kicking your self in the pants. When you are relieved to find out its something not to major.
having them replacing the CAM now. I don't believe it's the ECU either otherwise I would've had problems long time ago not just after the lost of compression on #4.
07-31-2009, 05:30 PM
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Are you replacing one or both? WIS says that they should be repalced in pairs. Also, what part number did you get (if its OEM)?
