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Thread: 1994 Chevy K1500 idles rough and stalls occasionally

  1. #1
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    1994 Chevy K1500 idles rough and stalls occasionally

    Hey I was wondering if anyone had any idea why my truck idles wierd and stalls at random times.
    When I start it up in the morning it usually idles back and forth between 1000-1300 rpms.
    Occasionally when Im slowing down or just sitting at a stop light it will randomly stall too. It always starts right back up and runs perfectly fine though.
    I really have no idea where to start and im going to be heading to college in the fall and really need to fix it.
    So thanks!

  2. #2
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    Your situation sounds kind of similar to what my '92 K1500 was doing when I bought it. I had to put a new catalytic converter on it before it would pass smog. The shop said that it was fairly common for the electronics in the distributor to go bad, causing a rich condition that would ruin the cat. For the most part the truck ran good. It would stall at idle when warm. There was a miss too. It soundsed like the shop was trying to ring more money out of me, but I wanted to get rid of the stalling at warm idle. I installed a rebuilt distributor myself and it never stalled again. The slight miss continued.

    I was putting new heads on the truck recently and met a mechanic friend for lunch. We were discussing the truck and it's history and he asked if I changed the O2 sensor. I had not. He said if the cat was bad the O2 sensor was probably compromised too. I replaced the O2 sensor while I had the heads off and the truck runs like a new truck now.

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    Thanks a lot for the help. I'll try that out and let you know if it works!

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    I have the same year and model truck...it was doing the same thing, so I had it timed again correctly and that fixed it...

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    Okay so I found that my O2 sensor on the drivers side manifold is broken. So I went down the road and got one off another 350 that is still in good shape. It has a purple wire coming off of it and a plug that came out of the wiring harness that was also purple connecting into it. I went home to put the 02 sensor in my truck and it has no purple plug coming from the harness..?
    Anyone have any ideas what I should do?

  6. #6
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    Welcome to the forum MDrumm03.

    First thought was "o2 on driver's manifold ? " Nice.
    My CA truck you find it after the Y-pipe on the psgr side.
    If you have mod'd exhaust or wires, this could lead to color games.

    Your o2 sensor does not have much if any effect on idle before engine warms.
    It does not function when cold. What color was your wire? Pics ?

    This will not likely solve the cold idle problem. Start by pulling codes.
    Easy to do, need only paperclip, pencil and paper, no fancy reader tool.
    There are several "how to" threads on that if you don't know how.
    You want to try to narrow what of several possible causes.
    o2 can cause stalling when warm, but should have set codes too.
    Please don't PM truck fix questions, bravely start a new thread for them. It is a forum afterall.

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    Yes there is two O2 sensors on the truck. One is on the y-pipe on the passanger's side and the other is on the drivers side manifold. It should have a purple wire going to it but it was broken and the plug was missing.

    It doesn't ever throw a check engine light or anything that I could have one of those "fancy readers" check for me.
    But I couldnt find any threads on how to do it with the paperclip, pencil and paper trick.
    Would you be able to tell me how or possibly post the link to the thread?
    Thanks.

  8. #8
    Full Member diceman1994's Avatar
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    New/old truck, just trying to get it right

    Hello folks, I'm new to the forum, I've learned alot so far and my issues are similar.

    I have a 94 K1500 5.7L automatic with 170,000 miles that I just bought. The plugs are new and gapped, wires good, distributor and rotor new.

    The truck idles between 600-900 rpms smoothly when warm, originally it accelerated from stop to cruise with a lag initially then it smoothed out during the acceleration, at a stop light it would surge but not not quit. I cleaned the TB with the proper cleaner and ran Techron thru the fuel tank, I also replaced the air hose from the valve cover to the TB spacer (Cracked) and now it seems to work properly. I STILL feel like a slight misfire during acceleration but cannot find the problem.

    A diagnosis was not possible because there is no power to the OBD I connector and the "Check engine" light illuminates only at idle but goes away when I accelerate, I can smell unburned fuel at that point.

    We found that this truck has no catalytic converter but the O2 sensor is still connected at the "Y". Any recommendations?

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    Okay im pretty lost now, I thought I would try replacing the whole distributor to see if that would help. But the one i pulled out looked brand new and I took it to a mechanic and he seemed to thing there was nothing wrong with it and it looked perfectly fine. Well I put it back in and bolted it all down and just turned it to where I thought it looked about where it was. So I started the truck to make sure it ran fine and it idled correctly, and for some reason it ran beautifully.. I was amazed. Unfortunately it didn't last very long, after it ran for a little while it just went back to rough idling and stalling. I'm lost now, its not throwing any codes and im not sure what to do now..
    I would really appreciate any help.
    Thanks.

  10. #10
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    Hi there you guy might want too change the injectors out. While it is running with the air cleaner is off look and see if one injector is spraying darker then the other if so they need to be replaced it will run alot better

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