[Biturbos4] MTM Boost ISSUE/QUESTION

Michael Benno mbenno at yahoo.com
Wed Dec 3 10:02:55 EST 2003

I am not sure I am following you, are you saying that after some amount of driving steady state, the car does not produce full boost?
A couple thoughts come to mind.... If you don't have a leak, then it sound like something to do with the boost pressure control system. You may want to run through the Bently tests (using vag-com). I would say it is something to do with your booster controler (N75) or your bypass controller (remember the ECU can activate the BPV's too they are not soley dependant on IM vacuum). Other possible components that could be problematic are the air temp sensor, and of course the MAF.
One could deduce that bad values from one of these devises could be causing your ECU to artifically limit boost.
I assume your problem became apparent after the MTM chip? It is hard to say if the chip is actually malfunctioning or if is a byproduct of how they have fooled the ECU to procuce higher output, and that your failing component is exlpoiting that modification.
Good luck trying to get anything out of MTM (or Hoppen), I have an irregular shudder on acceleration and all I could get out of them was, buy our spark plugs.
PS, you did adapt your throttle right?
Mike Benno
2000 A6 2.7t 6spd MTM Stage 1

"Witte, Michael J (HPFS)" <michael.witte at hp.com> wrote:
Installed a MTM chip this weekend (on 2000 TIP). 

When oil is warmed up, and boost is requested, I feel, and see (through boost gauge) the improvement, delivering 15psi boost (temps around 30 Fahrenheit outside. Run 20 miles, running on cruise control, switching cruise control off, boost won't get any higher than 6 psi. Detached ECU, reset and read VAG codes, banks lean and rich (indicating bad MAF, I know, its a 2000, MAF will be replaced shortly). Took another test-drive, no problems, on acceleration, easily 15PSI, kick in the back, butt dyno great improvement. On highway, whilst coasting at 70MPH, in fifth, accelerating to 85, again, boost up to 12-14 psi. Dropping speed to 60 mph, accelerating to 100 mph, 15psi. 

Fast forward, trip home, boost all the time, at 15psi, for 20+ miles, at last exit, boost won't come up higher than 6PSI (in any of the gears). Cruising through downtown, back to 2nd gear, boost runs easily up to 15psi....

Pressure tested, no boost leaks found, BPV's replaced with 710s less than a month ago. Any recommendations, suggestions, or does this chip has a mind of his/her own ?!!?
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