Today I had my car at a local track. It ran flawlessly the first 2 sessions. I filled up with gas and went out for the 3rd session. I immediately noticed a stumbling/surging during accelaration. The gauge was jumping from 1.7 bar to .5 to 1.1, etc. I can tell you there was no way it was actually hitting those pressures as the car was very noticably slower than earlier.

I jacked the car up and looked under it for loose hoses or ??? but everything looked good. Also everything looked good on the top of the motor.

Car details are:
'01 996tt with 24K miles.
FVD stage 1 flash. Up until today I never saw over 1.0 bar.
Stock everything else.
30K mile service with plugs, O2 sensor, etc done within 1,000 miles at Ruf in Dallas.

Any ideas?

Thanks,

 

any chance you got leaded fuel?

 

Do a boost leak check. I had one at the TB that wasnt visible to the eye but caused the symptoms you are describing.

 

Sounds like a boost leak, double check the hoses and pressurize the system to double check.

 

Yep boost leak check for sure and check the boost control valve. Any CEL?

 

Thanks guys.

I'll have the boost leak test done. I'm assuming this is dealer operation not DIY.

There were no CEL warnings.

 

Let us know what happens, good luck, I'm sure it will be an easy fix.

 

Check your diverter valves. The stock ones are known to fail.