Since my car was returned from the 30K checkup, I have had this odd off-throttle behavior.

In second gear and third gear, when I get in the boost below 3K rpm (I know this is 'boggin' it, but it happens sometimes), and then lift the throttle suddenly, the car lurches violently. Above this rpm things seem to function fine. And in higher gears, things seem better but it is still noticeable.

I thought this may be a bypass/diverter valve problem so got under the hood today to take a look around. First thing I noticed was a frayed and cracking diverter valve vacuum signal line from the front of the intake manifold leading down to the DV. Ahhh, says I, the vacuum signal line is cracked and causing this behavior. I replaced it (a long story in itself) and took the car out. No difference.

Next, I swapped my MC (now turbo5) Diverter valve with my stock one... no difference.

Next, I swapped the .8 bar Autothority chip ECU with a Stock one. Still no difference.

I'm not trying to blame the dealer here. But I am very confused. I stuck a pipe cleaner into the Intake manifold cable barb, no obstruction there.

Anybody got any ideas?

Sounds like your wastegate may not be opening, this may be due to the Vacuum ling to actuator, or solenoid, or one of the solenoind lines..

If they are of the same material as the DV signal line, they're probably hating life too.

Not sure how to test the solenoid. I suppose I could look at the VAG-COM software to see whats happening with the Wastegate Frequency at this time.

Paul Cormier

I've experienced pinging this is not it. Doubt it is any octane issue.

Fueling is fine except in this circumstance. It hauls ass at WOT with the 1-bar APR chip in it. Throttle response is crisp when adding throttle and even when subtracting it at higher rpms.

I am quite convinced this is something to do with the turbocharger plumbing and valving.

Paul Cormier

Hi,

No help here at all, but for what it's worth I get those same symptons on my unmodified A3 1.8T Sport (30K miles), and has done since 10K miles service (that's when I noticed it for the first time anyhow).

I was thinking about getting the Bailey DV30 valve, in the hope that it will solve the problems you describe...but it sounds like a new DV is not the solution. ...Things are never simple are they? :(

If you find a solution, would you keep me posted?

Regards,

AL