Chevy K1500 dies when coasting at low speeds or changing gears.

50

Asked by Jan 27, 2014 at 06:13 PM

Question type: Maintenance & Repair

Idles fine until I try to put in gear then it idles rough thereafter. The check engine light does
come on when coasting or trying to shift gears. Everytime I stop it dies.

11 Answers

17,625

Take it to advance or autozone.They will read the codes it for free. Repost here and we will help you.

9,055

K1500 what year. Could be the IAC Idle Air Control vale on your throttle body. It has a small electronicly controlled plunger that regulates the amount of air entering the motor when the throttle blade is shut.

2 out of 2 people think this is helpful.
50

Its a 92.

9,055

Never noticed your user name. NICE. 92 so she be a TBI. Pull the IAC out of the throttle body, back passenger side. If it's really dirty clean it. The plunger opens when you are at idle and closes as you take over the incoming air via throttle blade. It is supposed to open quickly if the (TPS or MAP can't remember) sees you drop off the throttle quickly (different code in the truck wtih the manual tranny - should open even quicker for shifting - clutch pushed - called dcel. Most people miss this difference when doing a manual) You can leave it out and plug it in and verify that it moves. I think it will fully extend when you turn the key on then start to retract as you try to crank it?? If it moves we need to look else were.

1 out of 1 people think this is helpful.
50

It helped a bit. I cleaned it off as well as the port it was in. I tried switching gears in my driveway. didn't die on me. We will see what it does when i go to work today (crosses fingers)

50

So the IAC moves but I still have issues. When I start it up it starts hard and then will either sputter and die or sputter for 10 seconds and then the service engine light pops up and it then idles fine. It sputters and/or dies at most stops and slow coasting (under 10 mph). It dies almost 100% of the time when changing to any gear. I replaced EGR valve, cleaned IAC, put in fuel injector cleaner and premium. Still has issue.

2 out of 2 people think this is helpful.
9,055

Did you plug in the IAC while it was out of the TB to see if the plunger moves freely. Do the test I mentioned above, the plunger should retract fully. Cleaning may of helped at idle but when you let off the gas while moving there is more fuel being injected the IAC has to retract further to add enough air to your engine until the decel fuel rate come back down to idle. I've had a few of these work for the first bit of movement but couldn't retract the plunger enough under load. They're not that expensive. These beasts are kinda of a pain until you get experenced enough on them. I was lucky enough to have two other TBI units in the yard when I was driving mine. Swap sensors untill it worked then go buy that one. Now I've bit the bullet and have OBD1 scan software and can read the live data from the computer, takes most of the guess work out. I haven't tried it on my '92 but works good on my POS GTZ. Good investment IMO.

50

the plunger moved. replaced the tb and that fixed the problem.

9,055

Did you compare the new and old. If you can figure out the bad part on it the rest could be stored for parts. Either bad IAC. Bad fuel regulator or bad injectors.

50

iac is still the original so that was fine. I had a tb in my parts box so i just put that on to see if it fixed the issue. the whole tb was really nasty. i dont think it was ever cleaned in the 260000 miles it has traveled.

if that doesnt work try to pull the vacume line off the egr and cap it off and see if that makes a differance then from there if it helps replace the egr. i just had the same problem with my 92

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