A RIDDLE

took the 90 to the shop yesterday as we had to adjust the windows. the pain of this is you need to leave the key in the on position to work the windows.

well we got the window adjusted and went to start the car and it would not stay running. figured i burnt the module by leaving the key on. installed new one plus cap and rotor and still the same. as i was low on gas (figured i'd wait to get it on the way home), i dumped a couple gallons in it to make sure there was enough that it was getting picked up. still not right.

figured if it was low on gas and the car was on a slight angle maybe the fuel pump burnt up. this morning i went and hooked up a pressure guage, turned the key and went right up to 42.5. cranking it stayed up too.

here is the riddle. if i keep my foot on the gas pedal it will run and as soon as i take it off it stalls. hooked a scanner up and tsp is working and so is the iac.

anyone have an idea what this might be? btw.. the car was running great when i got there plus while running it it does not set any codes.

Prolly cleared the "Learned Memory" if the batt got that low. You'll need to drive it a while to get it all re-learned, especially the idle speed. Drive it....

battery wasn't low at all. that's why i thought i burned the module out. have killed the battery before and when i jumped it it would run and idle ok.

It's possible the module was damaged. The fuel pump will only run for a few seconds without cranking the engine, so it's prolly not that. If it does turn out to be the ign module, then it was prolly on it's way out anyway....you just accelerated the failure a little....

Assuming all else is normal--by that i mean the engine will rev up w/no missing /skipping/ surging and is smooth other then won't idle except w/foot on the pedal---too me it sounds like a stuck or bad IAC ( I know you said it was working)---try tapping on the IAC valve w/ignition on-- with a screw driver handle or a small plastic hammer it may free up. Are you able to see % of the IAC opening with your scanner (being OBD 1 I'm not sure)--if you can it should be at a high percentage as the ECM tries to get the engine to idle by allowing more air thru the IAC valve. Since it will run-- IMO it doesn't sound like a ignition problem to me. If the IAC turns out to be a issue and if you haven't removed the the throttle body and cleaned it recently now would be a good time for a cleaning of that also.

mechanic at work said it was most likely the TSP. told him that on the scanner it was working and  said that there could be a bad spot on it that's why when i press lightly on the gas the car will run. don't think it would be IAC as the car wont run whether it is hot or cold and if you d/c it it should default to open position.

thanks for the input. tonight i will replace the TSP and see what happens. i also have a stick of dynamite here if all else fails. will let you know how it turns out.

well i had the stick all ready to light but was stopped. put in the new tps and still the same. you maybe right vaughn about the IAC. turned the idle up to keep the car running and had the scanner hooked up. everything looked ok and the IAC numbers were correct but then the more the car ran the lower the number went which is correct but then it went all the way down to zero.

i guess if it is bad it is not sending the right info to computer and would lower the rpm enough to keep the car from running.

Raising the idle speed by adjusting the screw on the throttle body will make the ECM try to close the IAC all the way(go to "0"). You didn't say if the rpms went down correspondingly, or if the rpms changed at all as the IAC counts went down.
Take the IAC out and see if it is gunked up....

Dave.... the IAC numbers/counts you're seeing is what the ECM is "asking "the IAC to do....in this case I suspect the IAC is not following "orders" so to speak.

[QUOTE=96LT1]And BTW don't light that fuse---after all you just finished getting it lookin' good... [/QUOTE]

that's one thing that stopped me from lighting it and i guess the guy from the body shop telling me he'd kill me was another.

i guess it was a coincidence(?) that this happened while we were working on windows or would leaving the key in on position do it too? it frustrating for both of us as we didn't even have the hood open and the car was running grear when i got there.

i have another IAC here and will swap it out in a bit. let you know what happens.

btw joel... the rpms stayed where they were as the number went down. i guess that's another sign IAC is the culprit?