Engine shake at idle

G Man said:

I have run the codes and there are none. I have a Pro-M processor, by the way

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I was really asking to do the cylinder balance test, which is a primitive misfire detection program the stock ECU will run to see if an injector is dead or a cylinder is not contributing for whatever reason. I don’t believe the Pro-m can do this.

years back, I had a slight vibration at idke that disappeared above idle. I thought it was balancer. I ran the codes and got nothing useful. I ran the cylinder balance test and it showed cylinder 4 was dead. I had been running on 7 cylinders for a year and didn’t know it. It pulled hard and would spin the tires easy into 2nd gear....on 7 cylinders.

I ohmed out the injectors and sure as hell one was dead. Got 0 ohms wren I tested with meter. Replaced injector and all was good.

I still think you have a misfire, so you’ll need to troubleshoot the old fashioned way. Spark, fuel, compression. You can use a pressure guage on the rail and a 9v battery to trigger each injector. Prime the pump, get a static pressure reading and then trigger the injector one by one. It should drop.

you can pull a plug and lay on intake to look for spark.

conpression i would save for last, unless you suspect something like a hanging or broken valve, or a blown HG.