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TBI trouble, code 42

Discussion in '1973-1991 K5 Blazer | Truck | Suburban' started by STV, Jul 13, 2001.

  1. STV

    STV Registered Member

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    Anyone have any common solutions to code 42? Says it could be anyting electrical - wires, module, ECM, coil, etc. Idles rough and choppy. 91 Blazer.
     
  2. Bubba Ray Boudreaux

    Bubba Ray Boudreaux 1 ton status

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    Here's what my Haynes says: Code 42 Electronic Spark Timing. If vehicle will not start and run, check the wires between the HEI module and the EST and bypass terminal. Check for a bad connection at the ignition module. Check and if necessary, replace the HEI module. Of course there's the disclaimer about seeking pro advice. " Here's what I learnt in school and from my chief mechanic. The code just tells you what circuit the problem is in. Service manuals(rare for everyone to have on, I happen to have an '85) have trouble trees for checking this stuff. Another disclaimer, my Haynes is for '67 thru '87 and I have an '87 K5. I don't think, someone correct me if I'm wrong, GM changed everything concerning the K5 in the late years due to the redesign of the pickup?

    "I am Republican. Not a baby-killing, tree hugging, land grabbing, touchy feely, hypocrite wuss democrat!"
     
  3. Thunder

    Thunder 3/4 ton status

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    Check your ign module in the distributor. You can pull it out and take it down to an auto parts store like napa, kragen checker ect. They can test it for you. and tell if it is good or bad. When the module is going bad it makes it run like crap.

    <font color=orange>GOT HORSEPOWER?</font color=orange>
     
  4. Mudfreak

    Mudfreak 1/2 ton status

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    When I got a code 42 in my 88 , I found that the oxygen sensor was shot, You might want to check this out also. Just my 2 cents.

    [image]http://www2.eboard.com/eboard/boards/9/50/68/tink/att-312393/88K5.gif[/image]
     
  5. bablazer73

    bablazer73 1/2 ton status

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    I just went through this with an 89 350 tbi van. code 42. turned out the map senser was showing incorrect engine vacume. we also had to replace the fuel filter(running lean) and has a lazy oxy sensor. BUT the only code it gave up was 42! We used a Snap-on scanner to see what was going on with this pig.

    your right. I don't understand the jeep thing!
     

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