eCoastAudi

I've been having problems with engine hesitation, brief cutout after warm-up and oil temp is 175-200 degrees or so. Sometime this results in a very unstable idle as well, sometimes not.

All the usual suspects (plugs, coilpacks, Coolant Temp, MAS, clean throttle plate) have been eliminated. Fuel trim looks OK.

I did notice that the timing jerks around (as reported by VAG) a lot at idle, even if the idle is fine. It jumps between 5 and 20 Deg BTDC. The funny thing is that even a touch of throttle input (+50 RPM) calms the readings down. I had dismissed the data as "noise"

Anyway, I recently noticed a similar timing jump while experiencing the hesitation/cutout, only worse (5 - 30 Deg BTDC). Accel position and Throttle plate were stable (I had wondered about a bad throttle body).

I get these codes some of the time, sometimes separately, sometimes 2 or 3 of them. MIL has come on once or twice.

19761 - B2: Exhaust Cam Pos. Sensor (G301) / Crank Pos. Sensor (G28) Incorr. Correl.
P3305 - 002 - Lower Limit Exceeded - Intermittent

16409 - Bank 2: Camshaft B (Exhaust): Advance Setpoint not Reached (Over-Retarded)
P0025 - 002 - Lower Limit Exceeded - Intermittent - MIL ON

18407 - Friction too High; Exhaust Cam Adjustment Bank 2 P1999 - 002 - Lower Limit Exceeded - Intermittent

So, it seems like culprits could be the VVT in the camshaft sprockets, the oil solenoids controlling them, cam position sensors, crank sensor.

Anyone have thoughts on what is more likely or possible diagnosis tips? Anyone else experience stuff like this? Bugging the H out of me.

This is actually an A6 but it seems like there is much more discussion of 3.0L quirks over here than on the C5 forum. Apologize for the verbosity but wanted to be specific.

shwndh

Do you hear clacking noise at startup or during the rought idle? If I were you, I drop this off at the mechanic ASAP and check out the Cam Tensioners. If one of those fails, it's just like the timing belt breaking. Bent valves and other damage.

I just put my 1.8t in the shop that had similar issues and it was the Cam position sensor so not as bad. But he did say if my tensioner went south it would be catastrophic. My 2 cents.

eCoastAudi

..no rear chain like the 2.8 30V.

shwndh

Uh, I just assumed there were. I'll shut up now and let someone else post. :/

Aarononymous

you might be looking at the canshaft adjusters & sloenoids, possibly sludged up inside or a broken oil ring or something.

eCoastAudi

Thought so too for a while but 3.0 is "different".