I think your O2 sensor is bad! This would pretrty much force you into open loop all the time and would REALLY screw up the way the ECU is handling the injectors. I'd verify your A/F gauge install and if your satisfied that it's getting good data then look at the O2. I'd go through the O2 sensor check in the Helms/Chilton/Haynes/whatever you have.

Wehn mine went bad it would read rich after a cold start and gradually go leaner and leaner until after ~2 minutes it would be off the scale lean.

 

I think you're right and will need to verify that. The car runs better in the morning when the a/f ratio jumos back and forth. AFter 5 minutes the meter is pin at rich and the surging RPM starts.

I hook up a switch between the 02 sensor and the ECU. FLip the switch but my a/f is still pin at rich and I get a CEL. Try adjusting the setting on VAFC but nothing happens. Is this normal? HOw did yours work.

 

Did it start to run like crap as soon as you changed over to the hack? I'm not saying it isn't your O2 sensor, but if it ran fine before the hack it seems unlikey. Unless maybe the problem is emphasized with the 450cc injectors.
Anyway heres a link for cheap O2 sensors.
http://www.oxygensensors.com/

 

All the switch is doing is disabling closed loop so that the ECU reads the actual O2 output rather than making changes to the pulsewidth based on the O2 output. If your fuel pressure is stock or lower and setting the 1000RPM narrow throttle point to -50% and your A/F is still pegged all the way rich at idle then there is something wrong with the O2 or the wires going to and from it or with the A/F gauge.

If the O2 is sending a bogus signal that is preventing closed loop it would be impossible to get the car to run well in any situation other than WFO (wide ******' open) with the 450's.


[Modified by 5 Liter Eater, 12:32 PM 8/15/2002]

 

It runs worst now as compare to before when I had the FMU setup. BUt before the a/f ratio was still pin at rich. My guess is that the 02 was always bad. With the 450 injectors the situation became worst.

Thanks for the site. I thought it was gonna cost me over 200.


[Modified by GOKOU, 6:46 PM 8/15/2002]

 

I don't know if I did it right but I hook up a switch between the 02 wire (white, pin 16 on P32 clip) and the ECU. My fuel pressure is at the low end of stock (40). My question is when you flip the switch should you get a CEL do to an OPEN circuit?

I will need to see whether its my 02 sensor or A/f that is bad.

 

I would have expected a CEL but I never got one on my GSR.

 

I'm getting a multimeter today so will verify that my 02 sensor is okay. Looks like my head gasket is leaking. I'm seeing oil underneath and around my engine. I can't beleive its leaking already. This could be one reason why I'm running rich.

I just hate all these problems!!!! :D


[Modified by GOKOU, 2:30 PM 8/16/2002]

 

Don't it suck !?