BSCA4

2003 1.8T, bone stock, misfire on 10 to 15 sec when engine cold, run perfect after that.
- New Spark Plugs last night NGK BKR6E, pre-gap at 0.32
- New Thermonstat
- No vacuum leak (replace all the check valves), if there is vacuum leak it would run rough all the time , correct?
- New Coolant Temp Sensor (the black one, AutohauAZ ensured me that it is compatible with the green, the box said green but it is black, I return one black to AZ and get another black one still misfire)
- Vacuum reading on my boost gauge is -18
- New fuel filter
Anything else?

Here are the codes:
4 Faults Found:
16684 - Random/Multiple Cylinder Misfire Detected
P0300 - 001 - Upper Limit Exceeded - MIL ON
16687 - Cylinder 3: Misfire Detected
P0303 - 001 - Upper Limit Exceeded - MIL ON
16686 - Cylinder 2: Misfire Detected
P0302 - 001 - Upper Limit Exceeded - MIL ON
17887 - Brake Boost Vacuum System: Mechanical Failure
P1479 - 008 - Implausible Signal - Intermittent

lyleswk

You didn't say anything about coilpacks, but I assume they have been replaced.

BSCA4

Coilpacks are R-version so I assume they are good. Plus if they are bad, would it just misfire all the times? Hope my theory is correct.

lyleswk

Hmmm, assuming you are not getting spark and your plugs and coilpacks are good, my simple brain would trace back from there: wires and ignition module? Not too familiar with the Audi in this regard, but I had issues with an older Nissan and it was the distributor cap being worn, so had bad voltage generation. Maybe the iginition module is not generating voltage or the wires are "worn-out"...guessing here. Maybe some others have some thoughts.

BSCA4

But it only misfire for 10 to 15 sec after that it run perfect This thing drive me nut.

lyleswk

So no problem on a "warm" engine?

BSCA4

Correct, after 10 to 15 sec, the engine run smoothly

bboissonneault

I have the same problem. Started after a timing belt job. I had audi put new coils on it as part of a recall before the timing belt. My wife drove it between the two jobs so I'm not sure when it started. I'm thinking coils.

Coils and plugs, by the way are greatly affected by temperature. Coils really only go bad as a result of temperature and impact. I would start there. I had the new revision D coils put on. I think I'm going to the revision E Hitachi's.

BSCA4

The TB was done at 110K miles way before I got the car (136K now, go the car at 129K). The only thing left is coilpacks and MAF. I am also thinking Revision E coil but that mean I have to pay for them (not Audi)

a44me2

Check your pcv valve, it may have a torn diaphram. A quick test is to remove your oil fill cap after starting your engine. If its bad this will result in misfires and the engine may even stall.