Really wierd idle/misfire issue with 2001 S4 stage 3

[karmannsport]

So, car has had a bad misfire issue since I bought it. Ive been starting to diagnose the problem and also contacted EPL about it since they are the ones that did the stage 3 install. Misfires are mostly on cylinder two, about 40 per minute, though there are also misfires on cylinder 4, 3, and 6. I moved spark plugs and switched coil packs and it did nothing. EPL said it is definitely an injector problem as they have replaced the seimens injectors that my car has with bosch in their kit due to idle misfire issues, though the PO said it didnt misfire for a while after the install so I have my doubts. However, tonight while replacing the coolant level sensor plug, I unplugged the MAF to see what would happen. Low and behold, misfire issue completely gone....while the clutch is depressed. Clutch up in neutral and the misfire returns, though not NEARLY as bad as when the MAF was plugged in. The car is also having an overboost issue as it is leveling off at around 26 psi but im contributing that to a bad passenger wastegate line. Any ideas what the problem could be? This is kind of a weird one.

[Dr. Jekyll]

Pressure test and look for and fix any and all leaks. Use a spray bottle with soapy water to find the small leaks that you can't hear. Be super anal about it. Swap ICM's if fixing the leaks doesn't work. See if the misfires switch banks when you swap ICM's. If that doesn't work, replace the coolant temp sensor. If that doesn't work swap injectors. If that still doesn't work replace o2's and start thinking about compression and leak down testing.

[NefMoto]

Siemens injectors don't flow well at low loads. Depressing the clutch increases the engine load. I assume you are only having misfires at idle?

I was not able to get my car to idle well until I corrected the injection time offset, and raised the target idle RPM and load.

You can get Bosch injectors, or you can get EPL to correctly tune your idle for the Siemens injectors.

[veggiemonster]

OP, just to clarify.

have you switched to ev14's then? and not on the deka's anymore?

i have maybe 1-2 misfires per minute that i can feel, compared to the every 2 secs with te deka's.


another thing, i know that the clutch changes shit with the engine but what exactly, i'm not sure

[GWerks]

Ingnition control unit for both banks?

subscribed. Let's find out what's going on!

[GWerks]

It could be an o2 sensor problem. Maybe sensors 1 on bank 1 and 2.

[NefMoto]

another thing, i know that the clutch changes shit with the engine but what exactly, i'm not sure

Depressing the clutch changes the target idle speed and target idle load.