Electronic spark control unit question

Discussion in 'General Chevy & GM Tech Questions' started by bstrange99, Jan 25, 2009.

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  1. bstrange99

    bstrange99 New Member

    I've searched, but with no results, so here it is. (I can't believe that I'm the first to ask about this).
    I have an '87 suburban with a tbi 350. I just bought the truck a few weeks ago, and haven't got it on the road yet.
    I'll give the history that I know:

    When I got the truck, it ran "ok", but not great. With some investigating I found that the throttle body had been drilled to allow access to the idle adjust screw. It had been adjusted, and the idle was pretty high and unsteady. I replaced the throttle body with a known good unit and that fixed the idle, and it ran a LOT smoother until I put it in gear, at which point it would just die.

    Next, I disconnected the battery for a while, hooked it back up, started it without touching the gas and just let it sit and idle for about an hour, hoping it would kind of re-learn. This didn't change anything.

    The next step was to check the timing. I started it again, let it warm up, un-plugged the wire so it would bypass, and the timing is dead on zero, right where it should be.

    So, what I've now discovered is that with the spark timing unit un plugged, it starts fine, runs fine, and stays running when I put it in gear, but the service engine light comes on.

    So my questions are, What does this thing do? Will it go through emissions without it? And could the problem be as simple as a bad electronic spark timing control unit?

    Sorry for the long post, but I figure the more info the better.
    Thanks for any help you can offer.
    Brian

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