2002 chevy 2500hd 6.0 has a very random misfire code p0300

Question

It is very sporadic. Does not do it all the time. I've had the knocks sensors and intake gaskets replaced, tune up and ecm ground checked. When it codes, it only lasts for about 5 minutes then runs perfect. My mechanic says it misfires on #2,4,6,8.

Answer 1

P0300 Random misfire

After the repair  where made , these are common occurance where the fuel injector of 5-7 , 6-8 fuel injector harness can get mixed There a TSB on this . This type of engine it is also a popular condition where the intake valve and the exhaust valve between those two valve  develop a hair line crack on the number 2 cylinder. These condition where noted by engine machinist But for now check the fuel injector harness here a TSB for this engine.

The following diagnosis might be helpful if the vehicle exhibits the symptom(s) described in this PI.

Condition/Concern

DTC P0300 Setting After engine Repairs.

It is possible to have injector connectors crossed for cylinder 5-7 and 6-8 to cause an engine misfire.

The engine misfire may not be detected and may happen during deceleration.

Recommendation/Instructions

If you have determined crossed injector connectors maybe a possible case, use the applicable SI document to validate the injector connector routing.

Correct the injector connector routing and evaluate for the concern.

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