[Gmecm] Re: Vortec L31 oscillating at idle

[Andrew Gibson]

Since the swap is on an older block and you are using the same ecm, Chances are you didn't quite get the crank sensor in the same exact spot. A crank learn proceedure must be done. I don't know how to do it without a scan tool. (Athough there is a proceedure floating around out there on how to do it without one) Once that is done you need to set the CMP retard (basically ignition timing but isn't the ignition) this does require a scan tool and you adjust the dist, rev the engine past 1000 rpm, check the reading on the scan tool, adjust again as necessary to get as close to 0 as possible. Once these two items are done it should run a lot better.

 
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