I have an 89 IROC-Z 305 TPI and it is running really rich. Not to the point where is floods but I would say almost that bad. I'm getting 13 MPG while driving conservativly. I recently put in a set of 350 injectors but I don't think that is my problem. Could the O2 sensor be causing it to run rich and cause me to have poor gas milage?

 

The car is going to inherently run rich with the larger injectors without
letting your ECM know what you changed. But, as you said it should not
have huge dramatic fuel consumption, but it WILL run rich..

How big are injectors? are they factory or aftermarket?

I did a Ford 24lb injector swap on my TPI car which originally had 22lbs..
It ran rich, smoked @ WOT and stank like an alley dog at idle. I got it back
to normal with alittle bit of trial/error.

The biggest question is this.. Does it run rich intially at start up? or
does the car's attitude change dramatically at operating temperature?

Open/closed loop operation, usually you can single out the source of
the problem by knowing when the car starts to under perform. My
past expierences are my TPI cars seem to run best with no issues at start
up. Until the car hits operating temperate and the ECM starts using
the sensor information is when problems start to arise.

02 sensor is a good place to start, as they should be replaced whenever
issues arise like this.. unless of course it is brand new. Timing, TPS, IAT
and IAC sensors can and will effect the car at operating temperature.


Did you do the injector swap yourself? Ive been tinkering with TPI
cars for awhile and I always seem to forget something or overlook a
minor detail.

I wish I could just do a swap or mod and bolt everything back together
the way it was with no issues.. but, we all know that seldomly happens!


my 2cents