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TBI Engine problem??? please help!!!!!!!!!!!!

Discussion in 'The Garage' started by protechk5, Sep 14, 2005.

  1. protechk5

    protechk5 1/2 ton status

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    Edit**** its fixed it was the coolant temp sensor


    Ok so last night i was putting a new radio in my 90 k5, anyways go to start it up this morning and it started to idle faster than normal. Drove down the street and when i came to a stop, I hit the gas to go and it dies. I turn the key but it will not start unless i have the gas all the way to the floor. It idles high in park, but when i put it in gear it ides slower, but real rough. If i try to hit the gas it will try to die unless i floor it, once i get going it will drive but still real rough. Blackish smoke is also coming out of the tail pipe. Never had any problems with this 100k motor until today, maybe i messed something up or shorted something when i installed the radio?? Any help would be great thanks in advance.
     
    Last edited: Sep 15, 2005
  2. dyeager535

    dyeager535 1 ton status Premium Member

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    Check your fuses first off.

    Did you splice wires or wire it off the accessory terminals on the fuse block. Actually, don't answer that.
     
  3. protechk5

    protechk5 1/2 ton status

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    yeah checked the fuses
     
  4. protechk5

    protechk5 1/2 ton status

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    i put some of that dry gas in, didnt help. It starts up with me holding the gas, then idles high until i put it in gear, idles rough for a second then seems to run fine until i try to hit the gas then it will die and then blackish smoke comes out the tail pipe?????
     
  5. protechk5

    protechk5 1/2 ton status

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    replaced the cap, rotor and plugs, did nothing, anyone :dunno: :dunno:
     
    Last edited: Sep 14, 2005
  6. Leper

    Leper 1/2 ton status

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    Thermosensor. Detects engine coolant temp and adjusts A/F mixture. If it goes bad it can send a cold signal to the ecu that will make it run super rich. Foot to the floor, black smoke...see, like a flooded carb
     
  7. Guss

    Guss Registered Member

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    just out of curiosity does that year have a idle air controler?
     
  8. protechk5

    protechk5 1/2 ton status

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    ok now it still idles a little high in park, and with the air filter off, i can see the 2 injectors, when i give it a little gas it seems like it injects too much gas and makes it die by flooding it
     
  9. SkinnyKenney

    SkinnyKenney Newbie

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    high idle.

    is it elecric choke, might be stuck open. the boggin down on acceleration might be a clogged fuel filter, thats what mine was. good luck, carbuerators suk.
     
  10. 350k5

    350k5 1/2 ton status

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    Hmm.. sounds pretty strange. After I installed my new stereo and amplifier I shorted something out and blew the fuseable link located on the firewall. Look along there to see if you see the remains of a wire that basically disintegrated.
    When it happened to me the engine was running and it started to run really rough then it died. However after the engine was off nothing received any more power. So that may not be it but that’s all I can think of from my own experience. :confused:
     
  11. protechk5

    protechk5 1/2 ton status

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    Edited***
    ok looks like your kinda close, my temp gauge is getting power, but its not reading anything over 100, so maybe thats a sign that coolant temp sensor isnt working right??
     
    Last edited: Sep 14, 2005
  12. dyeager535

    dyeager535 1 ton status Premium Member

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    Temp gauge has nothing to do with what the ECM sees. Take it to autozone, they have scanners that should show what the ECM *thinks* engine temp is.
     
  13. protechk5

    protechk5 1/2 ton status

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    does the temp gauge get its readings from the coolant temperature sensor, which is part of the ecm
     
  14. protechk5

    protechk5 1/2 ton status

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    anyone??
     
  15. randy88k5

    randy88k5 1/2 ton status

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    The coolant temp sensor (the one near the water outlet) is the one for the ecm. The one for the gauge is on the driver side block face around #3 cyl. Has 1 wire going to it, and it falls off pretty easially. I was haveing a problem like this. I hate to say it, but these problems take a while to diagnose, and require a multimeter and a vacuum pump.

    The only sensors youre gonna see that cause such an effect on the motor are pretty much TPS (in severe cases) and MAP. Other sensors might make it run funny and get horrible mpg, but wont make drivability THAT horrible. You want to check TPS (resistance or voltage, cant remember) through its movability. MAP you want to check voltage with a multimeter while applying vacuum to it (~15-20").

    My problem turned out to be a broken lower FI o-ring. The gas would fill the injector cavity, but with no/broken lower o-ring, the gas would just run down the intake. Ran way too rich. A TBI gasket kit ~$25, part # 17113116, cleared that up. didnt even see the o-ring when I took it out. Check your injector spray pattern with a timing light. If you can see physical droplets, like rain drops, you got something screwed up somewhere.

    Other things to take note of:
    Look at the catalytic converter in the dark, if you can see it glowing, that could cause a problem too. If it runs too rich for too much longer, you will destroy it. Has similar symptoms minus the smoke.

    Look at EGR function. Make sure you can move the diphram with your hands or a vacuum pump. When they go bad, it makes a real hard time to start. Wont cause smoke though.

    I can walk you through any procedures you want me too, but it will have to wait until tomarrow when I have all my manuals. Good luck...
     
  16. randy88k5

    randy88k5 1/2 ton status

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    Forgot to add...
    I would not check resistance of a sensor when it is hooked up to the computer. The computer runs on 6v and a multimeter runs on 9v. You will eventually damage the computer.

    If you are going to handle or unplug the computer, buy an anti-static wrist strap. Radio Shack has them. Its cheap insurance against possible damage.
     
  17. Leper

    Leper 1/2 ton status

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    Many posted answers can cause your problem. However we must remember "when" it started to happen. It is true that it may be a coinscidence(sp) that it started to happen after the stereo, I would not rule it out so quickly. A blown fuse could possibily cause your problem, but it would be morelikely to have a wire loose. Like a connector partially seperated or a wire loose in the connector or a ground wire not making a good connection. If you put a radio and amp in it, you moved alot of wires around. Go back under the dash and push all the connectors back together, even if you did not touch it directly. Look for any wires screwed to metal body parts. Wiggle them to insure ground.

    This goes pretty much without saying, but you did unplug all the stuff you just installed to make sure the components weren't the cause.
    Didn't you? That is the first thing to do in a case like this, but often the most overlooked.
     
  18. protechk5

    protechk5 1/2 ton status

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    thanks everyone for the help, it was the coolant temperature sensor along, it was thinking the engine was too cold and ketped flooding it. after all that it was a $5 2 second fix
     
  19. Russell

    Russell LB7 Tahoe Status Premium Member GMOTM Winner

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    Check your oil and see if it smells like gasoline. My TBI has been running rich, and fouled the oil with gas vapour blowby.
     
  20. Leper

    Leper 1/2 ton status

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    Glad to help.
     

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