I replaced my ECM and FCM plugs with pigtailed aftermarket plugs.  When I started the truck it idled normally but when i pressed the accelerator there was a loud grinding noise under the hood.  What could I have done to cause this?

 

It sat for over a month before I made the repair.

Disconnected batteries first.

Spliced wires one at a time.

Reset throttle sensor before starting.

No codes.

Take belt off and try again. If noise goes away, check for bad bearing somewhere....

Also check to make sure your starter isn't staying engaged....

Edited August 14, 20222 yr by Max Tune

I'm sorry but nothing electrical will cause grinding. I would check the trans selector make sure it making it into park completely.