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  1. #1

    Default Timing advance 1995 suburban

    Does anyone know where the timing advance wire is on a 1995 k1500 suburban 5.7 tbi? I have looked near the distributor cap,along the fire wall and behind the glove box.It is supposed to be a black/tan wire.I set the timing to 0 tdc(that's what the tag on engine compartment says), however the timing seems to go to 2-4 degrees before tdc.I read somewhere that you have to disconnect the advance wire when you set timing,then re-connect.Another problem I'm having is loss of power.I just replaced the intake gasket.(no leaks in oil or water).The truck idles fine,but bogs down when I put in gear.I'm going to take the tbi off and re-install to make sure there is not vacuum leak.I checked the map sensor(it's fine.) I haven't checked all the vacuum hoses for leaks yet.(not sure what to use.some people say carb cleaner eats gaskets up).I haven't checked the ground cables either.

  2. #2


    To set the base timing to 0 (which you should never have to do), you need to place the engine computer in bypass mode. On some vehicles there is a bypass wire, but best to read the correct instructions for doing this in a GM factory Service Manual set for your specific year, model vehicle. This would be in the section for replacing the distrubitor.

    They change this stuff from year to year, so no telling without looking at your specific years service manual (to be sure).

    Then otherwise, the timing is set by the computer. In general computer sensors which monitor the following things cause the engine computer to adjust the timing. If the timing is not correct, check these sensors for proper operation (testing instructions in GM service manual)...

    Crankshaft position
    Engine speed (RPM)
    Engine load (manifold pressure or vacuum)
    Atmospheric (barometric) pressure
    Engine coolant temperature
    Intake air temperature (retards timing when hot)
    92 GMC Sierra 2500

  3. #3


    The reason I have to reset the timing is because I accidentally wiped my mark off the distributor when I pulled the intake.I replaced all vacuum lines and replaced iac valve.It still bogs down when I put it in gear.

    Update.I found it.Well hidden behind glove box wrapped up in tape with a ton of other wires.
    Last edited by skipray; 07-16-2009 at 07:43 PM.

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