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TBI Help

Discussion in '1973-1991 K5 Blazer | Truck | Suburban' started by SickboySS, Feb 18, 2004.

  1. SickboySS

    SickboySS 1/2 ton status

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    ok, my truck is running like ass....

    1988 K5, 1989 TBI 350 out of a blazer, 88 wiring harness, 88 ECM

    it'll idle fine, but if you give it a lil gas it'll stumble and sh*t, in park or while driving (more when driving), and when i throw it in reverse it will die alot of the time or run like sh*t....but, if i stomp on it, it'll just get up and run like a raped ape with no trouble at all..

    any ideas what it could be? was there any differences in the harnesses or anything for the electronics?
     
  2. pauly383

    pauly383 Daddy383 Staff Member Moderator

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    Did your 88 have a 305 or a 350 originally? Try all the 88 sensors etc. , just a thought /forums/images/graemlins/k5.gif
     
  3. Thunder

    Thunder 3/4 ton status

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    Have you checked for trouble codes?
    Might be the TPS
     
  4. Fubeca

    Fubeca 1/2 ton status

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    Mine was running like that and it turned out to be the new autolite plugs and wires I had installed. I replaced them with AC Delco plugs and wires and it runs like a charm. I'm going down to yell at the local parts guy tomorrow.
     
  5. civicstomper

    civicstomper 1/2 ton status

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    [ QUOTE ]
    Have you checked for trouble codes?
    Might be the TPS

    [/ QUOTE ]

    I think a code 21 means TPS. I have been having a problem very similar to this for a while in my truck too. I got new plugs, wires, cap and rotor, MAP sensor(code 33 or 34) and o2 sensor(i believe its code 45), but what I think made the biggest difference was what I did with the air cleaner.

    It was supposed to have this tube that take heat from the manifold up to the top, but it didnt so I made one, and that seems to minimize the problem a lot. It still surges at times, but I noticed that its only when I have a certain amount of pressure on the pedal. If I go past the "bad" spot, its fine, if i go under its fine. This is what makes me think its the TPS.

    Not trying to take over the post and say my problems, just trying to list things I did to see if anything sounds similar to your truck. Good luck! /forums/images/graemlins/thumb.gif
    -pete /forums/images/graemlins/k5.gif /forums/images/graemlins/truck.gif /forums/images/graemlins/usaflag.gif
     
  6. SickboySS

    SickboySS 1/2 ton status

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    its not throwing any codes
     
  7. wolfy87

    wolfy87 Registered Member

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    Did you check the basics like doing a compression test, looking at the plugs, cap, rotor and check vacuum lines? Mine is doing the same stumbling right now... was hoping I could toss a few small buck sensors at it and clear it up, but my compression test showed my #8 cylinder was only pumping about 60% psi compared to the others. Put a few squirts of oil in that cylinder and the compression jumped up so its not in the valve train. Diagnosis - bad rings and I am going to need a new ENGINE! /forums/images/graemlins/shocked.gif /forums/images/graemlins/angryfire.gif Its an 87 TBI 350 that has 90k actual miles. Just getting a new engine rather than rebuild everything, have the block bored out.... bla bla bla. NOT cool. /forums/images/graemlins/frown.gif
     
  8. fad2blk99

    fad2blk99 1/2 ton status

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    I'm my '88 that stumbling you described was what I later found out to be detonation (/forums/images/graemlins/eek.gif) Being that it was my only source of transportation at the time. I had to continue driving it. I tried everything, from plugs and cheap sensors, to timing belt and fuel injector cleaner. Nothing worked. With in a few weeks it basically got to where it wouldn't run at all. I did a compression test, and while I don't remember the exact numbers, I had one cylinder at ZERO and a few others not much above 50psi. I pulled the heads off the side w/ the cylinder at 0psi and my worst fears were revealed. The detonation had chiseled its way through my pistons /forums/images/graemlins/yikes.gif Then, in came the new Goodwrench 350....
    Moral of the story.... If you can't figure this thing out ASAP. Take it to a service center!!!!!
     
  9. dyeager535

    dyeager535 1 ton status Premium Member

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    [ QUOTE ]
    If you can't figure this thing out ASAP. Take it to a service center!!!!!

    [/ QUOTE ]

    Or, get a scanner and see what the ECM sees. In your case detonation would have been seen by the knock sensor counts.
     
  10. SickboySS

    SickboySS 1/2 ton status

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    its got good compression....it'll idle fine and stuff, but if i rev it up 3 or 4 times it'll start to load up and stumble...its been like this for 3 years since we put the motor in, but now i'm driving the truck and if its gonna be simple i wanna fix it...

    it does the same thing in reverse, studders and loads up, but if i put it in neutral it'll go away....

    mabey an egr problem?
     
  11. dyeager535

    dyeager535 1 ton status Premium Member

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    If EGR was screwed up somehow, it should be consistent. EGR would mess with idle no matter if the engine is in gear or neutral/park.
     
  12. fad2blk99

    fad2blk99 1/2 ton status

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    Try giving the local Chevy service center a call and describe your problem. They might be able to suggest a few things. There are actually a few service techs out there who'll be glad to give advise, free of charge...
     
  13. chev4life

    chev4life 1/2 ton status

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    I had almost the same exact problem as you in my '87 TBI, mostly stock, replaced everything I could get my hands on, egr, tps, temp sensors, o2's, fuel injectors, anything....turns out that I got a bad coil that burnt my dist, so got a repro dist, new cap, rotor, etc, new coil, and coil wire....all better now /forums/images/graemlins/waytogo.gif
     
  14. civicstomper

    civicstomper 1/2 ton status

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    [ QUOTE ]
    its got good compression....it'll idle fine and stuff, but if i rev it up 3 or 4 times it'll start to load up and stumble...its been like this for 3 years since we put the motor in, but now i'm driving the truck and if its gonna be simple i wanna fix it...

    it does the same thing in reverse, studders and loads up, but if i put it in neutral it'll go away....

    mabey an egr problem?

    [/ QUOTE ]

    wow, that sounds exactly like my truck! i have gotten used to putting it in neutral when i stop at intersections and just listening to the pedal. I am hoping that all i need is a new TPS sensor (getting one tonight) and that im not hurting anything by driving it. Good luck with it, and keep us posted,
    -pete /forums/images/graemlins/k5.gif /forums/images/graemlins/truck.gif /forums/images/graemlins/usaflag.gif
     
  15. MA87K5

    MA87K5 1/2 ton status

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    I second the egr. I had a similar problem. But mine surged. I put a new egr in it and no more surging or stalling.
     
  16. SickboySS

    SickboySS 1/2 ton status

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    [ QUOTE ]
    [ QUOTE ]
    its got good compression....it'll idle fine and stuff, but if i rev it up 3 or 4 times it'll start to load up and stumble...its been like this for 3 years since we put the motor in, but now i'm driving the truck and if its gonna be simple i wanna fix it...

    it does the same thing in reverse, studders and loads up, but if i put it in neutral it'll go away....

    mabey an egr problem?

    [/ QUOTE ]

    wow, that sounds exactly like my truck! i have gotten used to putting it in neutral when i stop at intersections and just listening to the pedal. I am hoping that all i need is a new TPS sensor (getting one tonight) and that im not hurting anything by driving it. Good luck with it, and keep us posted,
    -pete /forums/images/graemlins/k5.gif /forums/images/graemlins/truck.gif /forums/images/graemlins/usaflag.gif

    [/ QUOTE ]

    thats exactly what i have to do, hahaha, i've gotten used to it too, but it would be nice to have it gone if its something simple
     
  17. civicstomper

    civicstomper 1/2 ton status

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    well, i tried the TPS sensor and that wasnt it. not only that, but when I was taking off the old sensor, one of the two bolts holding it on broke off /forums/images/graemlins/doah.gif /forums/images/graemlins/doah.gif /forums/images/graemlins/doah.gif
    I put the new sensor on with one bolt and part of the other holding it on, but I am hoping it wont get loose.

    Just be careful if you do take off the TPS, I'm not sure what I did wrong all I know was that bolt was really tight.

    Anyways, I was talking to a friend of mine who thinks it could be a bad distributor? I am just going to keep driving it like this until I get the time or money to do something better about it. Good luck with your truck, and let me know if you find anything that works /forums/images/graemlins/thumb.gif

    -pete /forums/images/graemlins/k5.gif /forums/images/graemlins/truck.gif /forums/images/graemlins/usaflag.gif
     
  18. chev4life

    chev4life 1/2 ton status

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    Just like I posted...I did all the sensors and crap to mine and nothing worked, ended up being the dist and the coil. I would recommend grabing a rebuilt dist for $100, a new coil, cap, and rotor. Piece o'cake to replace and once I got my timing set I was sitting pretty and still am! /forums/images/graemlins/waytogo.gif
     
  19. civicstomper

    civicstomper 1/2 ton status

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    distributor? /forums/images/graemlins/thinking.gif That is seeming more likely lately, as more people are thinking its related to the timing. I mean, $100 bucks is a lot, but if I could just fix this thing and be done with it that would be better. Thanks for the advice /forums/images/graemlins/thumb.gif
    -pete /forums/images/graemlins/k5.gif /forums/images/graemlins/truck.gif /forums/images/graemlins/usaflag.gif
     

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