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Bad knock sensor?

This is a discussion on Bad knock sensor? within the Technical / Maintenance forums, part of the General Discussion category; This is on my 91 chevy with a 350 tbi.. My truck is lacking in power and is running pig ...

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    Bad knock sensor?


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    This is on my 91 chevy with a 350 tbi.. My truck is lacking in power and is running pig rich, so i looked around and tested my sensors and did a full tune up and rebuilt the TBI and replaced the O2 sensor and its still doing the same thing.. but when i got to the knock sensor it tested bad.. i got a replacement knock sensor and it test fine.. but i just want to know if my problem here is cause of the knock sensor?? cause i wont be able to replace it for a little while and it be nice to know that is the cause of my problems and stop stressing over this truck..

    and to ad my IAC is acting like its going bad so ill also be replacing that but i dont think that would cause a lack in power or for it to run rich
    Last edited by 91LO5C1500; 06-03-2010 at 11:35 PM.

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    Re: Bad knock sensor?

    anyone?

  3. #3
    Registered User flyinbrian's Avatar
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    Re: Bad knock sensor?

    If your knock sensor is bad and telling the ecm to pull timing out of the motor, it may run rich. Be sure to only tighten the new sensor to 11-14 lb ft. If overtightened, it will send bad data to the ecm and you'll be back in the same boat.

    An IAC could cause a rich condition if it were to not open up when the ecm commands it to open. It's simply letting air into the intake.
    1993 K2500 Suburban. 454 poked and stroked to 496. Comp Cam roller valvetrain, JimD(454ss.com) bored TBI, Thorley headers, Edelbrock TBI intake ported and flowed. Innovate WBO2, TunerPro RT, Ostrich, Burn1.*Now running a Dynamic EFI EBL with a '7060 piggybacked to run the 4L80E.*

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    Re: Bad knock sensor?

    The IAC only controls the idle speed nothing else.
    04 K1500 Silverado EXT 3:73 gears, 5.3L 265/75-16,Pace Edwards tonneau,

  5. #5
    You won't like my tastes Swims350's Avatar
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    Re: Bad knock sensor?

    the coolant temp sensor could be bad too, they send more fuel when cold and less when up to temp. plus it's cheap like $12.

    Chris

    88 K1500 RCSB work in progress.

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    Re: Bad knock sensor?

    Quote Originally Posted by Swims350 View Post
    the coolant temp sensor could be bad too, they send more fuel when cold and less when up to temp. plus it's cheap like $12.
    checked the CTS and it tested fine but ill recheck

  7. #7
    Registered User flyinbrian's Avatar
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    Re: Bad knock sensor?

    Quote Originally Posted by redvett01 View Post
    The IAC only controls the idle speed nothing else.
    This is not true on TBI.
    When datalogging with the EBL you can watch the IAC open and close with the varying of throttle position.

    Check out AE - IAC Opening Fuel in TunerPro with the EBL and others.
    1993 K2500 Suburban. 454 poked and stroked to 496. Comp Cam roller valvetrain, JimD(454ss.com) bored TBI, Thorley headers, Edelbrock TBI intake ported and flowed. Innovate WBO2, TunerPro RT, Ostrich, Burn1.*Now running a Dynamic EFI EBL with a '7060 piggybacked to run the 4L80E.*

 

 

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