I want to see somthing so I heard I can jump the a and b termilnal and it will stay in open loop, I guess that is where you hook the scanner up to.

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I'm not sure how to stay in open loop, maybe unplug your o2 sensor? but I do know that grounding the aldl while the engine running doesn't do it. It will, however, show if you are running open loop or closed loop by flashing the ses light.

 

Tab, that might set a SES light for him... the computer leaves open-loop when it sees a changing value from the oxy sensor. Maybe he could switch the oxy sensor for a resistor (connected between the harness and ground)? I don't have my service manual around, but I'm sure it lists the voltage that the oxy sensor gives off when it's "cold"..

-Tom P (Hot rodded 1986 Firebird 2.8l) from http://www.f-body.net/mailbag/3rd/3rd_mailbag.html message boards

 

Unplugging O2 will definately get you open loop but not sure if true VE table open loop or CALPAC open loop... I would be VE table open loop. Don't cost nutin' to try it... SES light is no big deal.

 

Anything you can do to keep you in open loop will also set a code. What are you trying to accomplish by staying in open loop.
Jumping AB will put you in a really *** running mode, it does not work like a FI car where it will flash the SES light fast or slow, it will just flash codes like normal.
Unplugging the O2 or tem sensor (on the thermostat housing) will keep you from getting into closed loop. It will also set a code within minutes (or less.)
The best bet for clean open loop running is to unplug the TPS. This will make your 'puter think you are living at WOT. In theory this should set a code, but in practice, CCCS is pretty lenient towards flagging this one. If you let t idle for too long like this it will set, but if you are driving and/or your 'puter sees enough changes in RPM/load it will keep on trucking.
I am still curious why you want to run in open loop anyway?
...ed

 

Ed I drove around with my car in open loop for a long time and now that I got A heated o2 it goes in to closed loop, But I did not notice any diffrence, I just want to drive it like that again and see if I do notice a diffrence, I will pay more attenion.

 

Black, you probably won't notice any difference. Depending on what kind of driving you do you may see a *marginal* increase in gas mileage. If you are looking for a change in power/driveability, you won't see it.
...ed

 

Yeah, might not see any difference at all. Leave O2 hooked-up, though. The "right" thing to do.

 

Will unpluging the tps unadjust it? CAn I just do the paper clip thing?

 

Unplugging the TPS will not unadjust it, but i can tell you exactly what you will notice different. You will get worse gas mileage and you'll have a slight stumble at part throttle.
It will just run like *** if you do the paperclip thing.
...ed

 

Actually, a safe way to get your car to remain in open-loops is to unplug the CTS and put a resistor that causes the ECM to think the H20 temp has not reach 110*F.

I don't have my book to tell you the correct corresponding resistor code, but it will make the ECM think you just started the engine (when it is in open loop mode).

 

Glenn can you find out for me?

 

Hey glenn? thanks

 

Just unplugging the CTS will do the same thing. Unplugged = infinite resistance = cold coolant reported to the ECM. Of course, this will throw a code after only a couple minutes. I am willing to bet that it would still throw a code even if you had a perfect resistor value that made it think it was just under operating temp.
...ed

 

btt

 

Bumping a 2 year old thread. Man you must have run out of options, lol. I can answer the question above about aresistor value to make it look like it's under the closed loop enable temp. 1600 ohms would be 100'F to the ECM and is defiitely under the enable temp. 130'F is 815. Somewhere around/just over that temp is going to be your enable temp so i'd probably go somewhere just over 1k to try. But it still might set a code, and i have no idea why you'd want to do this.

 

yeah, I wanted to do it again, and I lost teh info I had on it, thanks

 

unplug the o2 sensor