Correct....... "open loop" refers to taking the O2 sensor feedback out of the A/F ratio control loop, preventing the PCM from learning the long term fuel corrections, or using the short term fuel corrections. Nothing else is ignored.

While the O2 sensor feedback is also ignored during WOT operation, GM does not refer to that situation as "open loop", but instead calls it power enrichment (PE) mode.

 

so would this narrow it down to o2's or the o2 to pcm inputs? Is there a way of testing the o2 sensors?

 

You could have a shop use an external o2 sensor like those used during dyno testing to see if it reads as yours does.

Or you could fool the PCM into thinking it's lean and then rich to see if it is responding the way it should. That would eliminate everything but the O2's.

However you will still need to see the O2 signals and the fuel trims.

 

Got the cable, if i use datamaster i can record what everythings doing and try to vary the rpm and throttle to get it in to the different cells correct?

And after i do this how do i upload it so you guys on here can see it?

Sorry guy's i'm green at this but trying to learn. Thanks in advance.

 

I finally figured out how to record the data, i did one test run while recording with the 02's unplugged and there were no problems at all. After this i plugged the o2's back in and the problem came back. i have both recorded files, and when it went into closed loop i got it to go into as many fuel cells as a could. How can i post up the files for you guys to check out?

 

I checked the file and the O2's are not reading right but staying in the same 100's group for more than they should. It might stay in the 500's for 5 to 10 staright reading and then change so they must be bad and need replacement. There are 8 total DTC codes so this is just part of the problem. The map and the icm are also showing problems.

 

i just bought a 93 formula, and it is doing this exact same thing...I started it this morning and it ran beautiful until it got warmed up? if i let it cool down, would unplugging the o2 sensor show any changes?

 

Ok, i have unplugged the o2 and the problem stopped! i believe now i will go buy a new o2.

 

i'm not sure if thats how you make sure thats the problem man. I wouldn't start throwing parts at it until you are sure.

 

well...how should i go about this the proper way? have you figured out why this is taking place in your car?

 

well thats where it gets complicated, i started a new thread with my datalog, i want people to see whats going on with my other sensors and fuel trims to see if anything pops out to them.

 

Yeah, i saw that thread too. i think maybe my car has a tune on it also? i cant really tell due to the fact that i dont have those kind of scanners. but i will say my thermostat stays nice and low all the time???? could this mean my car may have been tuned by the previous owner?

 

It could have a lower thermostat but doesn't mean it been tuned.