Hello All, I’d like to thank you all in advance for any help or information you may have. I have a misfire that starts with cylinder 1 and turns into a random misfire code. All the misfires are on the same bank. The misfire is predominantly felt during idle. I have swapped coils, plugs and injectors. The misfire does not follow the swapped parts. I decided to change the plugs and coils as well. There are no vacuum leaks that can be detected. I have taken off the intake manifold to check the intake valves for carbon build up and they are clean. I have checked for relative compression using a scope and all 8 cylinders appear to be fine. There are no other codes outside of misfire codes. Outside of performing a timing chain service, I’m not sure what else I can do or check. Thanks again!
Welcome to the forum.
A few questions to better help you.
1 do you have an actual compression test. If so post the results.
2 You said it starts with cylinder 1 and then turns random. I assume this means the other cylinders start to misfire as well. Is this correct
3 Do you have the actual code data and perhaps the vag com freezeframe data.
It could be a lot of things but before we send you on a chase it would be best to get as much information as we can.
Thank you so much, I bought the car just under a year ago and I absolutely love it. I don’t have the actual readings. I will do an actual compression test and post readings as soon as I can. Should I perform the compression test cold or hot? Using the scanner I have access to, I used the misfire counter and noticed that misfires were coming from cylinder 1. P0301 code always comes on first followed by other cylinders and random misfire code. I don’t have vag com, but I think I will buy it. There are a couple other observations I made, but don’t know what to make of it. The misfire started happening immediately after a cold start one morning. I heard a clunk/rattle, and immediately thought the worst. I thought the timing chain may have jumped. When I opened the intake manifold, I did notice a couple bolts had backed off slightly. I used an infrared thermometer to measure exhaust temperatures and noticed a significant difference from bank 1 and 2 post catalytic converters. Thanks again for the help.
a lot of good information there.
The intake bolts tend to back out so make sure to look more into that and check to see that none of them made there way into the intake track to the cylinder heads.
When you drive the car does it feel like its being held back… If you pull the DPs and gut them. Missfires are common when the cats start to go out and they do go out.
The comp test its best to do warm. Don’t add any oil let the motor do about 5 revolutions and capture the data. There is a comp test results post in the tech section.