I have a 2004 Allroad 2.7T (BEL) with 128K that has developed a misfire. The diagnostic code was P0355 for cylinder 5. I pulled the coil pack and plug for a closer look. The plug seemed okay so I used a wire brush to clean it a bit and reinstalled. Next I swapped the #5 coil pack with #4 in an attempt to eliminate either coil or plug being the issue. Since doing this, I now have multiple cylinder misfire.

I did search thru numerous threads on this topic and found a few leads...

I checked the connection to the MAF as well as inspecting for any dirt or oil. it looks clean...Next I decided to replace the Crank position sensor as it was an inexpensive part. Still no change.

I will say that the rough idle is only an issue at idle and lower RPM. It smooths out as it increases. also, the car starts up no problem.

My next idea was to change the original coil pack from cylinder #5 but because its now misfiring on multiple cylinders im not sure what to look at next. I suppose all coil packs could have gone out but it seems more likely that something has caused this...something upstream?

Looking for direction on the next step? trying to go with the easier, less costly options gradually working to the more expensive. I have heard possible ECU, jumped timing, but those are obviously very expensive. Any proven ideas are appreciated.

2004 Audi Allroad 2.7T
128K

 

I am dealing with this same problem with my 01' allroad as well. The rough idle is sourced to the ignition control modules. My 01' has them on the topside of the airbox. If you do swap these out they range from $ 60-250 depending on used parts or new from where ever. Be sure to get thermal grease(radioshack). I was not aware of this when i started my project and Im hoping this grease thing isn't a huge deal. Because i didn't use it in the beginning. Still have not had a reply to my post and i hope this helps the next step. Let me know how the diagnosis goes. It could help me with inequality

 

That last sentence is suppose to say help me with my problem. Not inequality. Sometimes predictive text from phones really does suck to have.

 

I had seen other posts referring to the Ignition control modules being a common problem, however I have a 2004 which does not have them. I believe the engine changed in 2003 to incorporate their function into the coil packs.

 

That one has me stumped a little. I would check the gap on your spark plugs. I did buy some plugs that needed to be re-gapped to .28 which is what other threads have posted. I think there still would have to be some kinda ignition or something the coil packs would plug too. Have you traced the coil wires through the loom to find what the may plug into next..

 

I think I'm going to replace all the coil packs first. I suspect that something upstream has fried them. I have read on here that some are replacing coil packs every few months. If I can get it running smooth again I plan to trade it for something more reliable as I believe it will cost more time and money than the car is worth. This is just the latest malfunction, I have a weird howling sound in the steering when the wheel is turned fully say when parking. I have an oil leak due to a failed pcv valve which was replaced, just fixed the front left air bag that was sagging from a hole in it. Last but not least is the timing belt change that's about due.

 

today I replaced all of the spark plugs hoping to get lucky and still have the misfire. the plugs were extremely worn down measuring about .060. I got some advice about trying to troubleshoot the misfire...disconnect all 6 coil packs and start the motor with the gas pedal depressed. he said the ignition sound should be a nice consistent hum and not have any peaks. mine had the consistant hum indicating its an electrical problem and not mechanical, thus ruling out a jumped timing issue. To date I have replaced the CPS, all 6 coil packs and all 6 spark plugs (NGK). Am i correct in assuming the next step is the ECU? my codes...P0300 RANDOM/MULTI CYL MISFIRE DETECTED, P0301, P0302, P0303, P0305, P0306 ALL CYLINDER MISFIRE EXCEPT 4, P0355 IGNITION COIL E PRIMARY/SECONDARY CIRCUIT MALFUNCTION

 

Also, I have the 2004 BEL engine, so no Ignition Control Modules, they are integrated into the coil packs

 

Also, ran sea foam thru the gas tank....still nothing as I was thinking clogged injectors

 

Found a reputable audi repair shop and decided to give in and see what they came up with...broken wire to #5 coil pack. Not sure how far back into the wire loom they found it but it fixed everything...what a relief although I'm disappointed that I missed something so obvious