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Old 03-17-2009, 05:04 PM   #1
sthomas
BMWCC 4928, BMWCCA 349578
 
Join Date: Oct 2003
Location: London, Ontario
Posts: 593
Balanced throttle at high RPM

I've got an RMS (Vortec) S/C on an OBD1 3.2L. I'm finding that the throttle response at high RPM is problematic. For instance, if I am accellerating at FT and then back-off a little at high RPM (above 5k) the engine reacts as if I suddenly lifted completely. The car reacts strongly (even a little violently). If I increase throttle a little, I get accelleration again, but when I lift (just a little) once more, I again get the whole car pitching forwards.

I'm thinking that the blow-off valve is opening completely and dumping all the boost. Shouldn't this be gradual though? I am working with MarkD to tune the car, but I'm thinking that this is not air/fuel, but rather the blow-off valve.

What do you think? If it is blow-off valve, any recommendations on replacement?
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2002 540i M-Sport
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