NiceS4

I'm getting:

16684 - Random/Multiple Cylinder Misfire Detected
P0300 - 35-00 - -
16687 - Cylinder 3: Misfire Detected
P0303 - 35-00 - -
16688 - Cylinder 4: Misfire Detected
P0304 - 35-00 - -

I installed new spark plugs... no go... I swapped around the ignition coils, spark plugs, and ignition plugs... no go. What's next to test?

Flyboy

Check the o2 sensor readings.

thejulex

However... misfire on bank 1 and bank 2 at the same time wouldn't be O2 since the banks have independent o2/trims/corrections. Unless both O2 went south at the same time which is highly unlikely.

Now, it could also be MAF readings being off. Which S4 specifically (year) you have? Is it with Bosch MAF?

Also, have you done boost leak test recently? A sizable leak would introduce extra unmetered air in the system causing the air to fuel ratio to be off.

Peter Badore

I would replace the ignition control modules. I used new Huco aftermarket ICMs that needed a little
filing of their bases to fit correctly. Also use lots of dielectric grease for heat dissipation. Or you could swap the existing modules with each other and see if the misfires change cylinders but sometimes a failing ICM will cause intermittent misfires in different cylinders. For a real "getto" test swap out one Bosch 2.7l ICM for a Hitachi ICM from an older Audi 12v 2.8l V6 engine car.

GregA

Timely post. I had a misfire yesterday AM, VAG-COM showed it was P0300 random misfires and P0304, cyl #4 misfire. Swapped coilpacks from cyls 6 and 4, codes stayed the same. Swapped the two ignition modules on the airbox and error moved to cyl #1.

$264 new from the dealer for an ignition module/POS (Power Output Stage)...so...

Source? Part number? ECS has Beru replacements for $145 but it would be nice to find one locally for less than dealer prices (NAPA has them for $249...<shrug>...)

Peter Badore

I actually used the Beru amplifiers with part number ZM063 0 040 401 063 on my 2.7l biturbo A6 and Hucos on the 1.8l turbos A4s. Audi doesn't call these ignition control modules POS for nothing! I bought both from All European Parts in Royal Oak, Michigan.

GregA

Thanks for the response. I decided to snag a Beru one from purems.com for $110 plus shipping...car's down a few days, but a lot less than the dealer wants...

NiceS4

2000

NiceS4

OK, i'm going to try swapping the ICM's and see if the misfire moves... hopefully it will. I still have to track down a power steering leak after this... SUMMER MAINTENANCE!

NiceS4

Alright, I swapped the ICM's and the misfire is now on the other side... Just ordered the ICM from purems.com as someone suggested above. THANKS A LOT FOR THE SUGGESTIONS!