Electronic EGR won't activate in 1992 Lumina?

Engine is the standard 3.1 multiport injection, not the DOHC. Vehicle runs fine, only has 60,000 miles and gets good gas mileage.

The car failed the NOX emissions part of the Ohio test. Everything else, HC, CO, etc is nearly perfect. This points to the EGR valve, which is an electronic EGR (GM calls it a digital EGR). The valve itself seems fine, all three coils measure correct resistance and when individually activated as per the GM service manual, cause the engine idle to stumble as expected. I pulled it and cleaned it anyway, it was not clogged up.

So, the manual now says it is bad wiring or bad computer. Wiring seems fine and the voltage supply in the connector is fine, 12 Vdc. Can the ECM fail this way, only the EGR circuits not working?

Dennis

Reply to
DT
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Sure it can, but before you go throwing an ECM at it, you need to make certain that all of the inputs that allow EGR operation are present and functioning correctly; Coolant temperature. P/N switch VSS, etc. Also, make sure you are testing the circuits at the ECM connector and not just under the hood. I see a lot of broken EGR harnesses where the wires are fractured just past the EGR connector. The early 90s were dark days for GM ECMs, many problems with cold solder joints and broken circuit boards from PROM insertion.

Call a GM parts department and see if the ECM part number you have has been superceded with a new part number, often the needed clue that you have one of the defective from brand new ones.

Reply to
Neil Nelson

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