92 1500 dies @ idle
 

My 92, 350, auto 2wd is dying @ idle. 250K miles. Have replaced ICM twice in about 6 months. 1 aftermarket, 1 Chevy. Seems to help for a couple months then problem returns. Replaced distributor also. Has had a low RPM surge and stumble at acceleration forever that haven't been much more than a nuisance. Everything else is original. Where do I start my shotgun approach to track the problem down? Want to keep the truck as it is cheaper than a new one. Thanks.

Re: 92 1500 dies @ idle
 

I had a few idle issues...... solved it by cleaning every ground wire connection on the intake, & carefully cleaned the computer chip pins.

Dirty grounds on older trucks, fool the computer !!!!!!!!!!!!!!!!!!!!!

Re: 92 1500 dies @ idle
 

My 90 would run great when cold but die at idle when warmed up. Replaced the EGR and it took care of my issue.

Re: 92 1500 dies @ idle
 

Thanks for the replies. Easy enough places 2 start. Hopefully this will be a short voyage.

Re: 92 1500 dies @ idle
 

Some more specific information. Truck doesn't die immediately but will idle at a red light (15-30 seconds or so) B4 dying. Tried drag race idling @ 1200ish rpm and didn't really help. Still died most of the time.

Re: 92 1500 dies @ idle
 

The stumble is always vacuum leaks, fuel pressure issues, or failing diagnostic devices that report to the ECU, or EGR. When this is happening its likely worse than you feel because the computer has a good deal of adjustment it can make. I had a breached manifold gasket causing mine, but it was breached internally pulling air out of a coolant passage. It's possible that the two are related because the computer has its hands full when a TBI engine is stumbling like that. Also if the truck runs cold the computer will over-fuel to keep temps down and save the motor. Since so many different devices can cause the condition it's a pain to diagnose. I've written a couple lengthy explanations on how to check out every part, if you look at my posts they'll be easy to find.

There is a way to sometimes make the computer fix the stumble without having to fix or change anything. If you unplug the Idle Air Control valve on the passenger side of the TB and remove and clean the IAC (takes an 1 1/8" wrench or huge cresent). Don't depress the pintle (the little piston thingy) it can damage the valve. Spray around the pintle and up into it with as much carb cleaner as you feel like smelling like, then re install it. Cycle the engine on and off three times to reset the IACs connection to ECU and the stumble should go away altogether until the ECU does it's regular reset or whatever you call it. I found this out trying to diagnose my stumble and it's worked on every TBI I've tried since but it may not in every situation. I was so happy that just cleaning the IAC fixed the problem cause it'd been going on for months. When I started it up in the morning put in gear and it died, killed again by the TBI ghost.

These motors last a lot longer than most of the ancillary parts. You can expect to do most of the sensors, smog crap, and all the pulley driven items at least once and likely more over the life of the truck. Also there is a rubber transfer hose on the fuel pump that is the only way it could work out I understand but is a facepalm kind of idea since you probably know where the fuel pump is. The pumps aren't crazy long lasting anyway and every fuel pump I've had go on any vehicle went with a tow anyway....

Also for some reason these engines don't like anything made by bosch so go OEM on smog parts/sensors.

Re: 92 1500 dies @ idle
 

I was editing that when the system decided I couldnt anymore

But first thing I'd do is try that with IAC and see if you can eliminate the stumble and you may find it's related to the stalling issue.

Definitely fix the stumble when you can. I couldn't believe how well the motor ran in my truck after it was fixed.

Re: 92 1500 dies @ idle
 

One little comment.... when I finally solved my idle issue by cleaning ground contacts, all during the troublshooting, my vacuum was all good.... no leaks.

Re: 92 1500 dies @ idle
 

Well, we're having fun now. Got erratic behavior @ 11-1200 rpm and 26-2700 with engine dying in the middle of high rpm runs. High rpm triggered check engine light but no code. Killed ICM after 3rd or 4th time. This ICM was from 9/13, OEM. Previous ICM was from 4/22 and was replaced after a sudden death incident, kept as a back-up. Gonna install and try to reproduce yesterday's events. Tach has been erratic thruout this. Had to hotwire brake switch a month or so ago. Looking at grounding points and possibility of a short someplace. In 2011 replaced dist because truck was doing what I call the herky-jerky at parking lot speed. That went away but was replaced by surging much like a big blower. Acts like it's loading up then clearing out cyclically. The herky-jerky still exists at steady throttle 30-40 mph. Of course my biggest problem is it's 250K and 22yrs old with all original components. Thanks for all your help. Working all the suggestions into diagnostics. At this point I'm still better off than having truck payments.

Re: 92 1500 dies @ idle
 

Did you put heat sink compound under the module when you installed it? Without it, module failure is likely. Did you use a substitute? Grease?

Have you replaced the ignition coil? It could be damaging the distributor modules.

You should test the charging voltage. Excessive voltage can damage electrical components.

Check the ground wire between the back of the passenger side cylinder head and the fire wall.

The ECM and engine sensors ground at the front of the intake manifold under the front intake bolts/studs or by the thermostat.

Also check the ground between the negative battery cable and the fender.

NOTE:
The IAC should not be cleaned with carburetor cleaner or other harsh chemicals. If the chemicals get down inside the IAC, it will damage it.

Re: 92 1500 dies @ idle
 

( I used to live in Encinitas BTW).... carefully clean your computer chip 'tangs').. also.

Your water temp sensor might be bad..... bad water temp sensor, computer might think it's very cold weather, raising RPMs?) But Oxygen sensor (good?), will conflict idle needs at same time.

Unplug water sensor will make computer think it's 40 degrees out, raising RPM.

Clean all grounds!!!!!!

If / when everything is fixed, ... when starting up first thing in morning, your RPMs will be sort of higher.... for about 30 seconds or so, then computer senses air temps, etc., then computer brings RPMs down to normal.

( our old oxygen sensor has only 1 wire..... "limited sensing information".... newer oxygen sensor vehicles have 4 wires.....giving more instant info to more components, .... no noticeable idle changes at startup)