Kogaborn

Hi everyone, I have a problem that has myself and several others very stumped. I have a 1990 C1500 with a 350 TBI and auto trans. The motor runs great, perfectly smooth, and no smoke, with about 124,00 miles on it. When the motor warms up and you try to leave, as soon as you put it in gear without any acceleration it will die. It starts right back up, but will repeat this about 85% of the time. If you hit gear and hit the gas right away, it will go, but as soon as you get to a stoplight and sit in gear at low idle, it dies. As long as you are not at low idle, the motor is a beast.I have had three different mechanics look at it and say they cant find anything wrong. I have replaced the IAC, ignition module, cap ,rotor, wires and plugs. And I have swapped out EGR, injectors, coil, and throttle position sensor to no avail.The last guy I took it to did a manual idle adjustment and it isnt dieing now, but the idle is higher thanit should have to be.I just ordered a new ECM and hope to try it this weekend. My question is, what tells the motor to shut down when the idle gets to low? The mechanic did notice the injectors are still firing for a split sec after the engine dies so I am thinking a spark issue. If anyone has ideas, please contribute, I am up to try anything I havent already.

old dog

1 thing you can check ,is the tank full ?they had a terrible time with the rubber tube that conects the elec pump in the tank to the pickup tube and the screen sock's on the end love to melt with hi accohol gas when used in older truck's .also how is the fuel pump pressure ?

Kogaborn

Tank never goes below half, I havent been into the tank yet, because pressure tests all say everything is good in there. Everybody I have talked to or that has looked at the truck is stumped. I have thought about going to the dealer, but dont want to pay for someone to scratch their head.

NoBrakes

Are you having any trouble codes? Is your transmition shifting down fine?

Kogaborn

I have had two different mechanics run scans on it, no codes at all. And yes, the tranny is shifting up and down fine.

Smkyb

Not sure, but could the torque converter be failing? Something could be causing the converter to try to stall at such a low rpm that the engine is being loaded too much. Just throwing my two cents in the mix.

Kogaborn

Actually Smkyb, you are the fourth person to mention the converter. I dont know much on how the tranny works....is it possible for it to fail at low idle but be fine any other time?

Smkyb

After talking to our transmission expert, he said the first thing he would do would be to put a scanner on it and see if the Torque Converter Controller is on. It could be that the switch is always staying on and not allowing the converter to unlock. Another thing to try would be to pull the pan and see if you had small metal shavings stinking to the magnet. That would be indicative of a brake clutch pack not releasing and causing your stalling problems. I hope this gets you closer to solving your problem.

Kogaborn

Thanks, i'll give it a try this weekend and post my results.