TIMRETN

Hello all- Got a good one here, and I'm at a loss trying to figure it out. So heres the scenario: 2003 A6 2.7T APR Tuned 106K miles etc etc.....
Had several codes recently, 3 cylinders misfiring, and camshaft position sensor over-retarded on both banks. Also I was past due for TB service. So I started by replacing all the ignition coils, which took care of the misfires, but the other camshaft position code remained (2 actually one for each bank). So then I dove in on the TB service, replaced EVERYTHING, except for cam and crank seals which looked ok, took 22 hours by myself (I know- ouch). Anyway, started it up when I was done and the two camshaft position sensor codes were cleared out. Car ran great, no issues.
However since then, in "93 mode" the car will boost to its normal range (spike at 20-21 and hold at 18.5 psi) but as soon as I get over around 3600 RPMs the boost cuts out to 5 psi, which I assume is limp mode boost pressure. I shift into nuetral and then back into gear and it will boost normally but then cut out. So I put it back into "stock mode" and just decided to drive in that mode to avoid problems. But now I noticed that every once and awhile (maybe 1-2 times an hour) it still will go into limp in stock mode, never lasts for more than a few minutes or a few miles at most but its frustrating. Does anyone have any ideas as to why this keeps happening, or anyone have/had similar symptoms?? Currently my CEL is OFF, with no codes when I scan with OBD. And when the car is not in limp mode it runs fantastic, no issues whatsoever. Also forgot to mention that this issue did happen prior to doing my TB service, but again very infrequently. I would like to know why this happens in general....and specifically why its happening to my vehicle. Any ideas or suggestions would be greatly appreciated. And please let me know if anyone needs more information. Thanks to all!

Peter Badore

Have you scanned the car with VAG-COM or an aftermarket scan tool?

TIMRETN

No, I havent done VAG-COM, I have the cable, but was never able to get it working. I bought one off ebay (not the RossTech). So I guess thats really my only move at this point eh? Thanks.

Peter Badore

Are the misfiring cylinders all on the same cylinder bank? If so then the intake camshaft adjuster may have malfunctioned and stuck the intake camshaft in only one position. This happened to an 2.8l 30V V6 A6 that I worked on recently. The problem was hard to diagnose because after deleting the DTC the conditions were not met to reset the fault code if though the malfunction was not present.

TIMRETN

I think you may be onto something but here the codes that all eventually appeared:
P0300-Random Misfire (multiple)
P0301-CYL 1 misfire
P0302-CYL 2 Misfire
P0305-CYL 5 Misfire
P0022-Intake Position timing (Camshaft A) over-retarded
P0012-Same as above but bank 2
P0303-CYL 3 Misfire

So it seems both sides of cylinders were effected. Did the car you worked on have similar issues? But the fix so far 6X OEM ignition coils, and the TB Service seemed to fix some of the problems, the car runs much better. But still gets intermittently stuck in limp mode.
It seems as stated the best idea would be to do the VAG-COM and see what pops up.

Peter Badore

I think you should check to see if your bank 1 or bank 2 intake camshaft adjuster is damaged or worn out. I think that the bank 1 intake camshaft adjuster for cylinders 1, 2 and 3 is the most susceptible to failure.
On the A6 that I worked on the lower plastic cam adjuster "foot" broke off and jammed the bank 1 adjuster causing massive misfiring on cylinders 1, 2 and 3 until the engine speed exceeded 1600 rpm (then the misfiring just stopped) and the engine was noisy. With VAG-COM you can monitor misfiring in the measuring blocks in real time by individual cylinder.