check engine light comes on when cold start and runs rough what sensor ?

Question

When I start my truck when cold out the check engine light comes on, the engine backfires and runs very rough I get a code P1391. CMP sensor. when the engine warms up it runs great. I shut it off and start it up again and the engine light is off and runs great again. I was told that the CMP was the problem I did change the crank sensor because the engine was stalling out. does not stall now, but I have the problem with the cold start. Could the intake air temp or the coolant temp sensor cause the CMP code to come on with a cold start ? I just want to be sure before I buy a CMP sensor. Thank you deno683....

Answer 1

Intermittent loss of CMP (cam position) sensor or CKP (crank position ) sensor

The running rough condition will cause these code condition, When the engine is first started , the ignition system fire sporaically and the injector fire sporacially, until it catches, there the CMP and CKP are syncronized, It this misfire at the cold start that start the code, Check the sparkplug also, whatever is the cause of the backfire will fix the code condition check the sparkplug wires especially at the ignition coil