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Thread: 87 2.8 tbi help

  1. #1
    spinldle drop with blocks *Blazin87*'s Avatar
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    Thumbs down 87 2.8 tbi help

    I have an 87 s10 blazer 2.8 I am having some idle problems. I have replaced tps, iac and cleaned the egr valve I have also replaced the plugs, wires. Cap and rotor. I noticed that the iac is not fully extended into the throttle body. Could the computer be the problem? I also unhooked the battery for a couple minutes. And tryd to reset it by goin 40mph I read the computer is supposed to reset it but no luck...... help

  2. #2
    Administrator Blazin Low's Avatar
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    is it only idle problems or while driving as well?

  3. #3
    spinldle drop with blocks *Blazin87*'s Avatar
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    Well when I'm driving its fine but when I let off it keeps driving like somethin is stuck maybe. If I'm at a stop light and put in nuetral it revs high but if I put it in park I seems like it goes down a bit

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    Administrator Blazin Low's Avatar
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    Sounds like a vacuum leak to me. It will usually cause a high idle, but drive somewhat OK. Are you getting poor fuel economy?

  5. #5
    Administrator Blazin Low's Avatar
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    Are you sure your gas pedal isnt just sticking? Verify you are getting the full span of the throttle with your pedal?

    I drove a 2.8L for 8 years ( just retired it ) I had the computer hooked up to a laptop and there you can see what the computer is seeing. Really helped alot in fixing the thing. If you can solder basic stuff, you can make your own data cable for about $4. The software is free.

  6. #6
    spinldle drop with blocks *Blazin87*'s Avatar
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    Well all of the vacuums seem ok and another concern is why the iac is not extending into the throttle body. And ill have to check to see if the pedal is sticking but I dnt think so.. before the high idle I was having problems when I came to a light or when I has in park it would idle rough and die out but after replacing the tps it fixed that but now idle is high.. coulde the ecm be goin out maybe?

  7. #7
    Administrator Blazin Low's Avatar
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    Its possible. If you have another ECU handy, swap it out and see....

    Did you check the EGR solenoid? Have you tried to bypass the EGR system entireley by capping it at the back of the TB?

  8. #8
    Administrator Blazin Low's Avatar
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    If youre bored open the cover of the ECU and look at the 80's electronics in there. I had to replace my ECU because one of the components was completely melted...

    Im just adding things as I think of them...

  9. #9
    spinldle drop with blocks *Blazin87*'s Avatar
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    No I have not checked the solenoid is that where the hose from the egr go's into? And I was reading that the coolant temp sensor can cause high idle due to the computer thinking its still cold is that true?? And how would I cap the egr?

  10. #10
    Administrator Blazin Low's Avatar
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    remove the vacuum line from the back of the throttle body that goes to the EGR solenoid. If you dont know where the egr solenoid is, trace it back from the EGR valve.

    Once the line is removed, get a rubber cap and plug the back of the throttle body.

  11. #11
    spinldle drop with blocks *Blazin87*'s Avatar
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    I will have to try that... if not I'm gna go crazy lol its not really bad but I like my cars to run smooth and the high idle gets to be a pain. If that dnt wrk I'm gna start lookin at the computer....

  12. #12
    spinldle drop with blocks *Blazin87*'s Avatar
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    Thank you very much for the info....

  13. #13
    Administrator Blazin Low's Avatar
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    As far as the IAC is concerned, Im pretty sure when its disconnected it should not be open at all and not pulling in any air.

  14. #14
    spinldle drop with blocks *Blazin87*'s Avatar
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    Ok now I'm gettin pissed.. I found a small vacuum leak fixed it and high idle is still there. I put on my old iac and it ran fine for about a block I put it in nuetral and high idle again. I have no clue on what to do next.... should I replace the computer or could there be somthin else

  15. #15
    Administrator Blazin Low's Avatar
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    Have you checked the timing? Should be 10 degrees, with the EST wire disconnected. The EST is the small plug inside the car on the passengers side, under the dash. You'll probably have to pull the rug back to see it.

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