i have a p28 ecu and it trips once in a while... it'll be cool, normal no check engine no codes, then sometimes it will throw a check engine and will idle at 2000 even when warm. i try to get the codes by crossing the wires but it doesnt flash, it just stays on! any ideas why it does this?! then it will go back to normal after a few starts, but it it starts trippin agin......

 

your key is in the II or on position when you are trying to jump the connector right?

the CEL is comming on for a reason and the code(s) are stored.

 

check if you have proper connection between the ECU and the harness, its possible something is loose and causing a problem once in a while

 

yes its on the II posisiotn, and when it is running good i pull off a sensor plug to make sure the codes will show and they do... nothing seems to be loose.