My '87 TPI iroc cranks and cuts off almost immediately except for when the service engine soon light stays on. If the light stays on after the car starts it runs fine and will run fine. It will idle, wind up fast and run like a p-off banshee. But when that light goes out or if the light goes out as normal right after you crank it she'll die - just like you cut the key off. pressing or feathering the gas does little to stop it from cutting off. I can get it to cough and sputter for a few seconds if i do that - but nothing else. i never know when the light will stay on. I changed the throttle position sensor mainly for good measure since it was cheap - no change. While the car was running fine i scanned the computer, when the light went out and the car cut off i scanned the computer. Both times i got a code 12 and that was all so the computer is operational. I heard somewhere that the SES light is an alternate ground for...something. and this problem seems to lend a little support to that or maybe i have a loose connection to a sensor. ( i have dis and reconnected several) Ya'll usually have great suggestions.

 

That light sholdn't have any affect on starting running or not as far as grounding, I dont think, but my Guess would be a chip or computer problem even though it isn't giving you a code esp. if there are any other related problems like fan running when cold etc, I've heard something to the effect of ground issues but not like what your having but you should always start with the stupid easy things first all grounds - conn. and just plain junk wiring meaning not stock.

 

My 89 would do that back when I had a flaky maf. It was like the flaky maf would give bad readings, and make it run like crap, stall, hard start, etc. Once it set the maf code, and the SES light came on, the car ran pretty good.

It's like whatever component is causing this, when it gets bad enough to set an error code, the ecm then ignores it, and runs better.

 

There are no add-ons. this car has 64k orig miles and is BONE stock. no amps, security sys. nothing like that. fan operates fine. when ses light comes on and car gets up to temp the fan comes on like it's suppose to. so i have no junk wires and really didn't put alot of stock in what i heard about ses light being a ground. Can't find anything about that in the wiring diagrm. But the maf is real expensive and that was the other possible culprit i'd thought about since 87 & newer maf are like tiny computers rmore than sensors. way more complex that 86 & older. but if anybody knew anything about that ses/ ground light thing i wanted to check. no one i've talked to can back that up & i've never heard of it before or since. But i'm surely no wiring expert. I think the maf too. but i was kinda hopeing it was somthing stpid & simple (and free) oh, well i guess i'll order it. i'll let ya'll know meanwhile i'll still open to all suggestions. thanks everybody

 

And the answer is......a bad maf. I changed it and it runs great again.

 

Good!

Funny thing is, when I had the same problem, years ago, I didn't have the money right away for a maf. With the maf unplugged, the car ran great, got 26 mpg highway (same as with a working maf), but the SES light was always on. I don't know how the ecm figures airflow with out a maf, but for that month or so, it did a good job of it.

 

Yeah, when i unplugged the maf the ses light came on and it ran. I didn't try to drive it like that though. it was just another clue. 26 hwy mpg!!!??? wow. I removed (properly) most of the sensors on my '86. just because i had only probs. out of them. everytime i turned around my car was broke down or not running right and it was rarely anything mechanical. But, i'm keeping the '87 as original as possible. Thanks!!