YellowBomberS4

I have a 2000 S4 with a MTM chip (stage 1) and have been having problems with boost on expressway driving. I'll drive for awile with the ability to run 17-18 psi, then out of no where 6 psi is the max boost available. Shutting the car off and then restarting seems to clear to problem. Not very feasible on road trips. Anyone have any ideas?? I haven't contacted MTM yet, maybe that should've been me first move.

R.C.

initialA4

have you tried vaggin the car?

YellowBomberS4

Forgive my ignorance, what's vaggin?

initialA4

www.ross-tech.com

Basically its a diagnostic tool

Audiboy

So, somewhere as the boost climbs, the ECU detected an inability to maintain that boost and goes into LIMP mode, which will reset once you start the car.

The issues could be a number of different things that could affect the ECU's ability to maintain fuel and timing at that boost. It could be sensors, it could be mechanical - such as plumbing leaks to more internal engine related. Get a vag logged to start. However, you may need some experienced help in what to vag in the 1st place. Some items that can trigger the soft limp are higher than expected load, boost deviation (plumbing and turbo related), ignition retard, intake air temps, LTFT, EGT on your car, MAF sensor inconsistent readings, many others.
Check your plugs, MAF sensor, air filter, plumbing leaks, etc also.

T-town TT

my guess is MAF is causing limp mode