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Timing check question

Discussion in 'Engine & Drivetrain' started by Tbruz, Jan 10, 2021.

  1. Tbruz

    Tbruz Full Access Member

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    1997 5.7L Tahoe.
    Can the engine timing be checked AND adjusted without the use of a bi-directional scanner, i e can you check it with an old fashioned timing light?
    Thanks in advance.
    Tbruz
     
  2. iamdub

    iamdub Full Access Member

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    You have to have a scan tool. The only adjustment you can get by twisting the distributor is maybe 2 degrees, and that's just from the slack in the hold-down tab. Even still, the PCM will be trying to adjust it while you're turning the distributor. I don't recall if you can use a timing light on the balancer. I wanna say there are marks and a tab, though.

    After it's adjusted, you have to perform a crank-to-cam relearn procedure, which requires a bi-directional scan tool.
     
    Last edited: Jan 10, 2021
    Joseph Garcia likes this.
  3. drakon543

    drakon543 Full Access Member

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    ive never needed to do a relearn but iamdub is correct a regular timing light cant be used. i cant remember what the rpm is but there is an rpm range that the ecm tries to hit 0° timing and you can match that to the timing mark. however all you can do with that is check the correlation for what the ecm thinks it sees to what its actually doing. if you try to do adjustments at that point the ecm will try to bring it back to what it thinks 0° is. the cam sensor is inside the distributor so turning the distributor is also messing with where the ecm thinks the camshaft is based off its programmed factory timing tables.
     
  4. Tbruz

    Tbruz Full Access Member

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    Thanks iamdub and drakon for confirming what I suspected.
    Unfortunately, I don't have a bi-directional scanner so ill need to engage a pro.
     
  5. drakon543

    drakon543 Full Access Member

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    if your near an advance auto parts they sell an innova for like 90 bucks or something that will do the job
     
  6. exp500

    exp500 Full Access Member

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    Tbruz- Sounds like you may have a bluetooth scanner, if so some use torque app to set timing. It seems most other apps willl do it also if you can find it in the menu. Cam angle sensor is one name. Anyway it measuses difference between Crank sensor and cam sensor in dist. Setting is "0" += 1 degree above 1000 rpm.
    There are a few threads on it. P1351 code is what you don't want to see. If you do not have P1351 your timing is correct. Hope this helps.
     

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