Turbo control in a GM ECM

[Ludis Langens]

Shannen Durphey <shannen at mcn.net> wrote:
> > The version with the extra (wastegate?) PWM output is from a 1985 Pontiac
> > Fiero with the 2.8 MPFI V6.
>
> Turbocharged?? I coulda' been a contender.
> >
> > >The turbocharged diesels with efi (94-current 6.5) use a pwm control to
> > >a solenoid in the vacuum line to the wastegate.
> > 
> > Vacuum?  Vacuum?  During turbo boost?  :-)
>
> Yup.  Diesels have no natural vacuum.  GM uses a pump on the front to
> supply it to the wastegate sol.

The 2.8 MPFI V6 is a gasoline engine.  What I was getting at is: when the
turbo is running, and the throttle is quite open, there shouldn't be any
vacuum anywhere in the intake or exhaust system.  Of course, for a wastegate,
all that matters is relative vacuum.

> > >Boost is measured by a map sensor.
> > 
> > Yup.  And it also "runs" the engine.
> > 
> Not on this app.  TPS is in gas pedal (Accelerator Pedal Position), no
> throttle cable, stepper motor operates injection pump, fuel is delivered
> based on APP and RPM.  

As I said, this engine is gasoline engine and it is a MAP (as opposed to a
MAF) system.  I can say with 100% confidence that the absolute position of
the accelerator (via the TPS) is never used to control fuel delivery.  (Unless
the MAP sensor is broken and a substitute MAP is being computed from the TPS.)
Short term relative changes in the TPS do affect the fuel delivery - but I'm
still chasing after those.

                   unsigned long BinToBCD(unsigned long i) {unsigned long t;
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ludis at netcom.com                 (t + 858993459 >> 2 & 572662306) * 3) : 0;}