I'll try to make this as clear as possible. 1991 350 z28. Car starts fine. After it heats up a little, it starts to surge, idles rough. Sometimes dies. After it dies, will not start until it cools a little. I noticed that when I turn on the vent for the air, it comes out through the defrost vents (don't know if this matters). One time I was driving and it shut down as if I was out of gas. Would not start right away until in cooled off. I checked for a vacuum leak...could not find one. I have replaced the MAP sensor, coolant temperature sensor, and knock sensor, oxygen sensor. No luck. I would greatly appreciate any suggestions. Thank you for your time.

 

Ohms check your injectors. If one is shorted it could have burned out the driver in the computer. I had this same problem last year although it would restart but still surge and die. Ran fine when first started cold, but after a couple minutes it started. Had to replace the injectors and computer to fix. It sounds like a fuel problem.

 

I'll look into the injectors. Also, why is it that I am not throwing any codes at all? My ses light does work, it lights up like clockwork during start up. Any recommendations as to the types of injectors I should get? Thanks fellas.

 

i have the EXACT same thing happeneing to me right now but i have a 91 TPI 5.0L 302 i would be driving and my fuel system would like turn off as if i ran out of gas... when i turn it back on and rev the engine it would work fine for about 15-20 min then shut off again.... very streesfull now it doesnt even wanna run...and if it does it just runs at a very rough idle and if you hit the throtttle at all it will die.. :-( ......... i checked / replaced everthing except the injectors and i have yet to ohm them out thats my next step....

 

Kbaker, if and when you correct the problem, please let me know what you did. Thanks.

 

What are your fuel pressue readings?

 

I have a rough idle in my '85 T/A, and it will idle rough, and stall when at a stop while in D. Everything is in order, AutoXray scanned, all sensors are working properly, no vaccum leaks etc. I did replace the injectors recently, they were leaking and often the car would let out a puff of fuel at start up. The injectors didn't solve the problem, (but were a symptom) and one other oddity is that when it stalls, the MAF readings drops like a stone, but with the motor off, it reads 9 gr/sec. In addition, fourth gear is listed as engaged. Could a previous owner have replaced the chip, I've heard of tricking the car into "highway mode", to improve fuel mileage. For reference, the prom ID is "31".

 

Also, the temp runs up to 220 on the gauge at idle in drive.

 

I believe that I fixed the rough idle. When fiddling with the spark plug wires, I pushed down on the one that goes from the distributor cap to the (don't know the name of it/the shortest wire coming from the dist. cap coonects to it). Anyway, one of the connections (there's two of them; the bigger of the two) was barely on there. After I connected it, the idle seemed to be fine. My car still died about fifteen minutes later though? Someone suggested that I check the fuel line pressure...how do I do this and what should it be? The crazy thing is that after it sits a while, it will start right up again. Thanks for your help.

 

the same thing with mine again... after it sits for about 2-4 min it will start right up... but when u hit the gas it dies... i changed the Throttle possition sensor today, that did nothing wasted $45... i just now went outside and tryed pressing donw on the connector u said just for the heck of it nothing happend... i replaced the fuel filter and i dont have a fuel pressure reader of any sort so i disconnected the fuel line in the motor and pointed it away from the vehicle and turned the ignition to the on position and fuel shot out probably 2-3 feet so im sure the fuel pump is working fine.. i havent "ohmed" my injectors yet but i will tomm morning... there has to be some answer out there... i mean it runs @ idle but dies with any kind of throttle... please help :-(

 

all i did to fix it was:
when the engine was idleing...(roughly of course) was
one by one (One at a time leaving 7 plugged in so it would keep its idle) unplugged each individual fuel injector wire harness and sure enough on the 6th one when i unplugged it it ran smooth..reved up and everything...
so what i found is that the 6th injector i unplugged has a short in it so everytime i plugged in the bad injector it would short all of the rest of them out... so they wouldnt run or would barely run...so i am driving around on 7 cylinders and its smooth but at least i am driving... i am buying one new injector tomm... when i put it i will post if everything is back to normal again...
i can smell gas by the back end of the car now and im not sure why its only after ive been driving for a while and i stop.. :-( hope its nothing too bad :-(

 

Just buy a whole new set.

305 are 19#

Order the SVO/Ford racing ones from summit.

One factory type injector will set u back prolly $60-80 from a parts house.

If one is going I can guarantee the rest are.

Pull all inj connectors and ohm them out. Stock should be 16-17 ohm.

Above 12 is considered serviceable by GM, u will prolly find a few out of whack.

Do them all and u wont regret it.

later
Jeremy

 

Same symptoms for me. #6 cylider injector shorted. A shorted injector is bad for the computer. You may find after replacing the injectors it will still have the same cold start running fine and think you fixed it. But, after warming up a couple minutes, back to the same surge and stall. Fix: replace computer. You may get lucky, just fair warning.
Good luck

 

I have the same problems you all are talkign about but when my car stalls i can just fire it back up once i get off my rear and turn the key. Now that i read the thing about unplugging individual injector wires, i'll give that a shot and see how it goes.

It was fine before i took the intake off and redid gaskets but nothings loose so its not like i have a vac leak(that i know of) and then after i put everything back on I've been having problems.

 

i had the same problem my car would only stall when it got waemed up so i unpluged the 02 sensor and the car runs fine. try it.

 

replace your icm(ignition control module)and your car will run fine i promise.just did it to mine a few weeks ago,they get warm and short out

 

sounds like a bad idle air control valve to me.

 

Was your car doing the same thing as the others'?
Mine is running fine everyday for short distances to and from work. I took it on a longer drive (45min) and it stalled on me in the middle of driving with no warning. Would not start again, as if a fuel problem, and after 15min or so - would start but rough idle. Same as the other guy - if you give it gas/throttle, it shuts off. The next morning - as if nothing ever happened and started right up.
Someone else recommended the ICM to me, so just getting your synopsis too.
Thanks!