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Thread: 350 tuned port injection problems again

  1. #1
    Senior Member DYNO OPERATOR
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    350 tuned port injection problems again

    ok i had the vacuum line unhooked while the motor was running when i hook it up it dies on me anybody no what the problem is? i surely dont and any help will be greatly appreciated

  2. #2
    Senior Member DYNO OPERATOR
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    Which vacuum line? If you have large vacuum line unhooked, say brake booster for an example, and hook it back up quickly, the idle air control valve may not be able to react quick enough to keep it running. Will it idle if you start the engine with the vacuum line hooked up? If not, you may have a bad or stuck IAC valve. It's really just a computer controlled vacuum leak.....
    Johnny

  3. #3
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    ok i'll try to crank it with the vacuum line hooked back up but i dont know alot about these fuel injected ones but the vacuum line i am referring to goes from the throttle body and connects into a little black ball thingy idk what it is but the engine is in an 81 chevy silverado it used to be in a 1988 formula firebird and it wont run rite now and i have til next school year to get it running or i'll be riding the bus and theres noway im doing that again this year lol

  4. #4
    Senior Member RACING JUNKIE mopar1968's Avatar
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    You have to reset the ''Idle Air Control'' motor again :!: get someone to start the engine keep it around 1500 rpm, hook up the vacum line and slowly let it come to Idle again you may have to repeat this if you let it die out, try to keep it running so the computer can reset :!: :!:



    ''JUST MY TWO CENT'S WORTH''
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  5. #5
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    ok thanx mopar will do also the MAF is off and that is also helping it run better do you no why.

  6. #6
    Senior Member RACING JUNKIE mopar1968's Avatar
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    Do you mean MAP sensor?
    Head's up the true drag race!!

  7. #7
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    No the Mass Air Flow sensor but i have heard ppl talking about the MAP sensor what exactly is that?

  8. #8
    Senior Member RACING JUNKIE mopar1968's Avatar
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    Manifold Air Pressure, air flow thru intake, it monitors vacum in intake to regulate fuel mixture along with 02 sensors, Mass Air Flow monitors in coming air flow to engine, if the engine runs better with it off then it is faulty, If it run's good and no check engine lamp just leave it off.
    Head's up the true drag race!!

  9. #9
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    it runs good with it on or off and the check engine light is on wether or not its on or off

  10. #10
    Senior Member SENIOR BUILDER
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    Leave the MAF sensor on. It tells the puter how much air is going into the engine and witht the o2, rpm and other inputs it tells the puter how to fuel and idle it. Get yourself a scan tool and LEARN whats going on if you wanna hot rod it....unless daddys got deep pockets.

    Good Luck

    Craig


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