My wife's audi has been troublesome lately. Replaced timing belt and ICM's recently and car ran good for a couple of months. Now the car idle bounces up and down when cold and then after 2 minutes it turns to a rough idle with pops and what-not. Changed the MAF today and no change but I noticed that the driver side downpipe area was glowing red after only idling for 4-5 minutes. No driving or reving the engine. Any idea what could be going on here? Car was running good till she started it up in the morning and noticed the idle problem.

 

So, thought maybe one of the new ICM's went bad so I replaced each one with one I knew was good and no change. Car has all new plugs and coilpacks installed about 4 months ago. Please say this doesn't have to do with the timing belt. I do NOT want to go through that again.
I don't hear a vacuum leak but could that be a possibility?

Anyone in central FL with a vag-com?

 

This could be a lean condition causing the hot exhaust temps. Perhaps faulty EGT sensor(s)?

 

Still no luck. Can't figure out why the idle bounces up and down at start up.

 

The irregular idle maybe caused by a vacuum leak. You may not hear it as the sound of the engine and fans may not allow you to do so.

 

It is also possible that the cams jumped one tooth on the hot side and the exhaust valves are opening too soon. I would double check the t-belt timing. Get this fixed quick or you may kill the turbo on that side.

 

Well, I'm definitely not driving the car any and only letting it run for 3-4 minutes at a time trying to find the problem. How do I check the timing? About to buy a vag-com. Would that show if it is a timing issue?

 

Good call on that one.

OP: Do you have a CEL on the dash?

 

So I bought a Vag-Com. Here's the readout..

9 Faults Found:
16805 - Warm Up Catalyst; Bank 1
P0421 - 35-10 - Efficiency Below Threshold - Intermittent
17972 - Throttle Actuator (J338)
P1564 - 35-10 - Under-Voltage during Basic Setting - Intermittent
16487 - Mass Air Flow Sensor (G70)
P0103 - 35-00 - Signal too High
16684 - Random/Multiple Cylinder Misfire Detected
P0300 - 35-00 -
16688 - Cylinder 4
P0304 - 35-00 - Misfire Detected
16690 - Cylinder 6
P0306 - 35-00 - Misfire Detected
16689 - Cylinder 5
P0305 - 35-00 - Misfire Detected
17978 - Engine Start Blocked by Immobilizer
P1570 - 35-10 - - Intermittent
16686 - Cylinder 2
P0302 - 35-00 - Misfire Detected
Readiness: 0000 0000

 

what's causing all the misfires? New MAF, new ICM's, new coils, new plugs..