sid350

Any update on fixing the issue?

Ridin Dirty

Not going to believe it.......still observing...but on the advise of John @ Protosport as a first measure....."run a tank of Sunoco 94 and see what happens". So far so good. Still think it's idling rough though. But no more hesitation in about the last 200 miles with that gas.
Can't be......no way..... doesn't it need something like a titanium/carbon fiber hybrid alloy blessed by Tuscan monks to fix it? Can't be that easy, can't be...probably just jinxed myself....
Joe

Bullmrkt

I was going to start another thread about a similar issue I'm having, but then I saw this one. This is a new car I just picked up in Chicago over the weekend. Anyway, right around 4k RPMs the car abruptly and rather violently cuts power. I was aware of it from the PPI, but he did not have time to diagnose and find the problem. We both suspect the DME, because its conditional, 4k RPM under full/hard accel and high load (3rd, 4th). This is no hesitation, it's a full-on fuel cut at peak boost pressure which is right around 4k RPM correct?

It's difficult to communicate with the seller, because he consigned it through a dealer and they won't give me his info. The dealer does believe a tune is present, and I'm waiting to hear who's it is. The PO is a poster here on Rennlist, allegretto I believe is his username.

Anyone have any ideas? I don't think this is fuel related, its some kind of hard torque limiting or something.

Thanks

Ian

Rovman

Same here. I was about to start a thread myself but I have been experiencing a similar issue.

My car has the same rough idle(except when cold, car is running in closed loop) . Than when at steady state throttle like when cruising on the interstate, the car has a slight surge/miss that seems to get worse the longer you drive. This occurs at any RPM, not just at the 4k to 5k area.

My car is a full FVD level/stage 3 car with every supporting accessory for the stage.

So far, as the engine and tranny was coming out for clutch change, we replaced all plugs, plug wires, rotor, cap, coil as well as new sensor at the flywheel, new boost sensor. While we were there we also changed all of the Vaccum hoses on the engine as well as the rubber intake plenum unions as some of mine were deformed and had cracks. The fuel filter is new as well. Car has new MAF sensor

To date, no misfire codes have been thrown, possibly the FVD tuning has eliminated some of these functions. Need to research.

Next we were going to check the 4 O2 sensors and see if there was a bad sensor possibly? Other than that, what's left? would be injectors and possibly tainted or faulty ECU. Is there anything else obvious I left out? The car runs so good under acceleration that I can't imagine it being something really major, sometimes a small little issue can have a major impact.

I really would like to get this sorted as I absolutely love the car and am so happy to finally have a 993 TT. I have spent a good pile of cash on the car so far, would be nice for the car to run good after all spent.

Anyone else having these issues? Thanks to the earlier folks who posted on there past issues and remedies.

Basal Skull

Do you all have aftermarket ecu/programs? upgraded motor mounts?
I worry that many ecu's are programmed aggressively and tend to pull timing (then boost, then fuel) as knock is detected in max boost/pulls. I have heard using stiffer/solid motor mounts can exaggerate the issue since the knock sensors are tripped easier.
Better fuel as shhaz says may improve the situation if this is the case.
Every time the battery is disconnected may reset the ecu, requiring some time for the ecu to try to compensate.

Rovman

Good question. So far as I know, my car has stock motor and tranny mounts...

Quadcammer

i feel like I might have this also. Its not a misfire, it just feels like you are very slightly pedaling the throttle. Could it be the wastegates opening are causing a momentary drop in boost?

Has anyone replaced their maf to solve the problem. I'm thinking another thing could be the oxygenated winter fuel blend as this didn't happen last fall.

Ridin Dirty

In the end she just had gas. "Burped" with a few fresh fuel tanks and eventually the symptom did not return.

....and new MAF is prohibitively $$... unless I know it's dead I wouldn't consider replacing....I just sprayed mine.

OverBoosted28

Another point if you suspect bad fuel, would be the plugs. They'll suffer from the poor fuel and probably should be replaced. When I fought with these symptoms it ended up being poor spark from the higher boost pressure. Closed the gap to about .020-.022 and been fine since. Not an issue if you have a twin plug or fully ungraded ignition.

Quadcammer

You can get the maf for $280ish from amazon, so not hateful, but good to know.

My plugs are basically new, and I'm not going through that headache again. I'll just keep running it as it runs fine otherwise. The plugs are gapped at .028 like they were before so it should be fine with my stockish boost.