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who has a program for their truck

Discussion in '1973-1991 K5 Blazer | Truck | Suburban' started by trogdor4x4, Jun 10, 2004.

  1. trogdor4x4

    trogdor4x4 Registered Member

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    I am using TurboLink4.0 to read my computer. when I am idling at the stop light and the motor is warm, I get a random rough idle and the computer doesn't see anything. Does anyone have normal readings for the 5.7 motor or have an idea of why it is happening. the rough idle isn't bad, but it is annoying (we all know how these things are). I have a new O2 sensor and it runs smooth in park and neutral. If anyone has information on "normal" readings, it would be most appreciated. /forums/images/graemlins/k5.gif /forums/images/graemlins/1zhelp.gif
     
  2. dyeager535

    dyeager535 1 ton status Premium Member

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    From what I have been learning, you really need to share data with someone else that has pretty much exactly the same rig you do. I think you understand that, but just making sure.

    TPS adjustment is fairly critical, one easy thing to look for with the scanner is the minimum/maximum for it with the throttle closed...anything within the .5V range will be ok.

    Not sure what your interface is, but you want to make sure it is going closed loop, and you want to make sure that when it is, the O2 sensor is bouncing between rich and lean, not constantly one or the other.

    Also watch EGR operation, but doesn't sound likely if your problem is so random.

    Do you have a service manual? The flow charts are pretty in-depth, that might be a good way to start. In reality from my two tests of problems, the flow charts from GM were wrong, but hey. Still make you think, and inspect things.
     
  3. asterix

    asterix Registered Member

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    i'm having the same problem but have not connected a comptuer up yet. if you are in my area if you wnat we could get together and see what mine says

    Brett
     
  4. trogdor4x4

    trogdor4x4 Registered Member

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    Dorian, the TPS reads .47V. The manual I have from GM does not have fuel injection or computer stuff in it, it tells me to refer to another manual from GM. Another wierd thing happened when I shutdown the program, my motor began to rev up to about 1000rpm in gear and has remained, I don't know why. It did return to normal after I turned off my motor and restarted it.

    Asterix, I am in Houston, I don't think I am close enough for us to check out our trucks and compare; though, would be nice to be in Colorado right now.
     
  5. dyeager535

    dyeager535 1 ton status Premium Member

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    .47 is a bit low, but still within tolerance. Apparently .54V is "ideal" but not going to make a huge difference...it shouldn't change unless someone messes with it, so it's probably always been that.

    With some of the diagnostic tools and modes that they put the ECM in, idle is increased. I know with my '87 TPI ECM, getting data from the ALDL sets the RPM at 1000RPM. If the problem doesn't return, I'd attribute it to that.
     
  6. detailer03

    detailer03 1/2 ton status

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    My 89 does the same thing now. I put new injectors in it the last time, about 100,000 miles ago when it did it the last time. I looked at my spray pattern. It is not as good as it should be. If it is not a fine mist, then the problem is with the injectors. I am just too lazy now to replace them. I just put the new motor in. The old one expired with 230,000 on it.
    Check your injectors spray patter.
     
  7. 4xrick

    4xrick 1/2 ton status

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    all good points and valid but one thing not mentioned is this I had the same problem but it liked to die in gear would start iddling very bad then just die so I figured injectors or mayme tps but it turned out to be the stupidest thing the fuse for the idle control the computer/test never even knew it was blown i replaced the fuse and never had a problem since. well till i threw a rod that is.
    /forums/images/graemlins/histerical.gif /forums/images/graemlins/histerical.gif
     
  8. jjlaughner

    jjlaughner 3/4 ton status

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    [ QUOTE ]
    when I am idling at the stop light and the motor is warm, I get a random rough idle

    [/ QUOTE ]

    I was thinking it was the torque converter going bad, since in park and nuetral it idles fine... /forums/images/graemlins/thinking.gif
    I haven't been getting error codes (check engine light) but I've been trying to get a winaldi cable setup just to checkout what the computer is seeing. Do you have a site for the turbolink program?
     
  9. realsquash

    realsquash 1/2 ton status

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    It's probably not helpful but you need to figure out what codes it's setting.

    The TPS is used for very little other than accelleration compensation so having it set a little doesn't do much of anything. The P4 TPI ECM's also autozero it when the ignition is turned on, but the old TBI ones aren't like that.

    Andy
     
  10. dyeager535

    dyeager535 1 ton status Premium Member

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    Try bumping TPS up (like throttle is being depressed) without distrubing the throttle, and see what happens with idle.
     
  11. imiceman44

    imiceman44 1 ton status

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    Well I have been diagnosing my friends truck which is an 87 TBI and he has it worse. When he get's to a stop, it idles rough with poping noises for 10 seconds then dies.
    We have tried lots of scenarios, then we hooked it up to computer with the WINALDL and it showed problems with EGR, and wouldn't go into closed loop, so we changed EGR and O2 sensor, and that was after I was checking the Cap and found it bad so we replaced module cap and rotor.
    After we replaced all these parts, the poping went away but it still dies after 10 seconds.
    Now since i am not doing the testing, I cannot confirm that it only does it in gear although I have asked him to try and pop it in neutral when he stops to see if it make a difference.
    Then we went and changed the IAC sensor and motor, we removed CAT (maybe retricted) and MAP sensor, as well as the whole Throttle body with the injectors from another 87 I have that was running fine.
    Still exactly the same.
    I don't think we still have any vacuum leaks, so do you think there is anything else we didn't look at?
    I am hoping it's the same problem we both have, and I sure hope he is keeping it in gear and the TC is bad or the lockup is engaging and lock ing it up.
    Otherwise is there anything other than the ECM unit?
    Does turbolink 4.0 have more than WINALDL?
     
  12. realsquash

    realsquash 1/2 ton status

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    Then restart your truck and see what it does...

    Andy
     
  13. dyeager535

    dyeager535 1 ton status Premium Member

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    If you physically move the TPS, the voltage stays the same it was once you move it, just like the distributor. TPS voltage in the .5V range wouldn't be the standard it is if that wasn't the case.

    If *I* do that and restart the truck, I'll get an error telling me the throttle is open too far for the amount of air the engine is ingesting. For a MAP setup, I'd surmise the amount of vacuum seen wouldn't correspond with the throttle opening the ECM is seeing. Does TBI not use .5V as the closed throttle TPS voltage?
     
  14. realsquash

    realsquash 1/2 ton status

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    Well since you are running an old MAF ECM (C3 style, 1227165) it's going to behave similar to the TBI setups. A P4 (like a MAP TPI) will autozero the TPS when you turn the ignition on regardless of it's position. In fact I am using a nonadjustable LT1 style TPS myself now.

    I forgot you had a MAF setup (pity /forums/images/graemlins/whistling.gif). Those ECM's are soooooo slow!

    Andy
     
  15. dyeager535

    dyeager535 1 ton status Premium Member

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    [ QUOTE ]
    Well since you are running an old MAF ECM (C3 style, 1227165) it's going to behave similar to the TBI setups.

    [/ QUOTE ]

    So why are you talking about TPS autozeroing when he is running TBI?
     
  16. realsquash

    realsquash 1/2 ton status

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    Dorian, it's because you posted about the relevance of your TPI setup to his TBI w/o specifics, I was just trying to point out that there might be a difference. The later TBI's were P4's, also.

    There is so much stupid bullshite on the internet about EFI I want to cry. Think your O2 is bad? /forums/images/graemlins/rolleyes.gif Probably not. Think the TPS is set wrong? /forums/images/graemlins/rolleyes.gif Doesn't do much of anything regardless of what you think.

    Want some real troubleshooting? Try getting the codes out of the computer. Don't bother even posting if you can't bend a paperclip and read a manual first.

    Andy
     

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