93 3.4 dohc grand prix stalling

[BumpRacerX.com]

Howdy gang,

Played with the car today for a while. In situations where I go from heavy throttle to no throttle, I'm getting a stall. And then I have to actually feather the throttle in order to get the car to restart. If I let it crank without throttle, it will not start.

Any ideas?

[86FieroSEv6]

Have you checked the minimum idle air rate? An improperly adjusted throttle can cause this. As well as a possible Idle Air Control Valve fault, such as sticking closed.

[BumpRacerX.com]

Have you checked the minimum idle air rate? An improperly adjusted throttle can cause this. As well as a possible Idle Air Control Valve fault, such as sticking closed.

How do I check the minimum idle air rate. If the throttle was improperly adjusted what would the proper procedure be to adjust it? I did swap a different IACV into the car and it didn't seem to help.

[86FieroSEv6]

Turn the key on (engine off), bridge A to B at your diagnostic connector (just like retrieving flash codes). Once the CE light has flashed 12 three times, disconnect the IACV. Now, turn the key off and remove the jumper from the ALDL (Assembly Line Diagnostic Link). Then, and you will probably have to touch the throttle for this, start the car up, get it to temperature and gently let off the throttle. It should idle at about 500rpm steady. If it does, then minimum idle air rate is correct. If it does not, then you adjust the throttle stop to achieve a steady 450-550rpm idle. Once that is done, you shut it off and plug the IACV back in. Then turn the key on for a few seconds and then off for ten seconds. Do that three times to re-zero the IACV. Then start it up and go drive above 35 for five or more minutes. Tedious, I know, but that was the state of the art when that vehicle was built.

[BumpRacerX.com]

Turn the key on (engine off), bridge A to B at your diagnostic connector (just like retrieving flash codes). Once the CE light has flashed 12 three times, disconnect the IACV. Now, turn the key off and remove the jumper from the ALDL (Assembly Line Diagnostic Link). Then, and you will probably have to touch the throttle for this, start the car up, get it to temperature and gently let off the throttle. It should idle at about 500rpm steady. If it does, then minimum idle air rate is correct. If it does not, then you adjust the throttle stop to achieve a steady 450-550rpm idle. Once that is done, you shut it off and plug the IACV back in. Then turn the key on for a few seconds and then off for ten seconds. Do that three times to re-zero the IACV. Then start it up and go drive above 35 for five or more minutes. Tedious, I know, but that was the state of the art when that vehicle was built.

Thanks, that seemed to help. Won't know for sure until I can get some track time again, but it seemed to help. When I started the car up with the IACV unplugged it wouldn't even stay running without throttle. I had to crank the hard stop up quite a bit in order to get it to idle without the IACV. I'm guessing someone previously had this thing set wrong.

[86FieroSEv6]

If it seemed as though you had to make an excessive amount of adjust, make sure you are using the correct OEM PCV valve and that the PCV pipes/hoses as well as the throttle housing and idle air bypass ports are clean and clear. Also, once you have confirmed a good idle under ECM control, measure the real time voltage at the TPS and get back to us. It will be a clue as to whether or not you have correct throttle angle.