TBI EGR issue

Discussion in 'The Garage' started by Russell, Apr 13, 2005.

  1. Russell

    Russell LLY Escalade Status Premium Member GMOTM Winner

    Jun 23, 2000
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    Edmonton, Alberta
    Hey guys!

    I've got an odd issue with my 89 TBI's EGR.

    When I was re-wiring the engine after I bought it (had a majorly hacked up wiring harness due to a crazy PO who put an LP system in using speaker wire, a crapload of electrical tape, and household style marettes...) I accidentally hit and broke the EGR solenoid's vac port off.

    I got a new solenoid, but upon installing it, the truck started to run kinda poor. It would idle fine, and was great in the upper end, but when you went to accelerate, it would bog, and want to die. Unplugging the solenoid's electrical eliminates the problem. This lead me to believe that maybe the solenoid was leaking. So I pulled the wire off the EGR and went for another test, the truck still did the exact same thing. Unplugging the connector from the solenoid totally elimates the problem, wether the solenoid's vac lines are hooked up or not.

    I even tried plugging an entirely different solenoid in, and it still did the same thing.

    What could possibly be causing this? The solenoid either gets 12 volts or it doesn't. I can't see how having the solenoid plugged in could be the sole cause of the truck running poor?
  2. dyeager535

    dyeager535 1 ton status Premium Member

    Dec 13, 2000
    Likes Received:
    Roy WA
    I'd be looking at the wiring for the EGR solenoid. (especially with PO's l33t wiring skills)

    Check both of them for continuity to ground, and see what you come up with.

    Since the problem is only related to the electrical (happens without the EGR valve actually being active) it leads me to believe that circuit is messed up and the ECM is thinking something that isn't happening is, (like leaning mix out because it thinks the EGR is working) or vice versa.

    I don't see how it can be anything else except that wiring. Knowing how GM wired things, the 12V wire is probably constant when the vehicle is running, and the other wire is the ECM switched ground.

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