Seemingly Random Engine Flat Spot Problem When Accelerating

[skymast]

I have an 02 TT with manual transmission and 35,000 miles on it. I have recently changed the DVs and did the ECU stage 1 flash. The spark plugs were changed at 30K. I had the problem I am getting ready to describe before I did this work.

Sometimes after driving a while and turning the car off and restarting, when I start driving again, I am feeling some fairly dramatic 'flat spots' during acceleration lower end acceleration. It is almost like the engine is stopping / missing for a split second and starting again. Note exactly the same but sort of like the car is in limp mode.

This happening very early in acceleration and is very noticeable (the car bucks when it hits the flat spot which occurs soon after shifting). I am not noticing anything odd at at idle when this happens and I never see a check engine light. The only thing that I have noticed, is that seems to happen more after a longer drive (say 60 miles or so) and when the fuel level is at about 1/4 tank. Note that I typically use Shell Premium and I never push the limits of the car.

Thanks in advance.

Edited August 5, 2007 by skymast

[Loren]

I would start by looking for loose pressure hoses.

Also, check the diverter valves to see if they have any cracks.

[wross996TT]

leaks...hose or connections

[skymast]

the DVs are new and I had the problem before i replaced them. This is a random problem, so would it actual be a hose?

[loulimm]

Could be the clutch slipping.

[SpawnyWhippet]

Could be the clutch slipping.

surely that would have the opposite effect and cause the engine to scream rather than flat spot? Also a wonderful burning clutch smell?

[jonhahn99]

Could cracked ignition coils cause this sort of issue? I have an 01 with 72k on it and I experience this "hesitation" around 1800-2000 RPM. Not helpful to look good pulling away from a stop!

[Dietz]

Could cracked ignition coils cause this sort of issue? I have an 01 with 72k on it and I experience this "hesitation" around 1800-2000 RPM. Not helpful to look good pulling away from a stop!

Had the same problem - just coming on trottle or the same for just coming off throttle the car would feel "sluggish".

Replaced MAF, plugs, reflashed to stock, checked diverter valves, check for boost leaks, just about given up -

then heard the suggestion of the coil packs.

Had them change out all of them - 7 day delay - not in stock from Porsche.

All I can say is that - that was it! Totally transformed the feeling of the car.

Perfect now...

Good luck - hope you find it.

Deetz.

[racer_mitch]

Wouldn't (shouldn't) bad coil packs give a CEL code..?

[roadsterdoc]

Try cleaning your MAF.

[smistry007]

Try cleaning your MAF.

what he said!