Engine misfires what to do?

Asked by Harold Jul 15, 2021 at 01:32 AM about the 2005 Cadillac DeVille Sedan FWD

Question type: Maintenance & Repair

my OBD list code as P0300 ( random multiple cyln. misfire detected). I have
replaced the coils, plugs, injector wire harness, fuel filter, air filter. Also had the
fuel injectors cleaned and new seals installed. The MAS was cleaned with the
correct spray as well the throttle body was sprayed with it's own correct spray.
Still idles and runs very rough. what's next ? ECM/PCM, knock sensor ??????

3 Answers
3,370

Justin answered 3 years ago

Vacuum leak? Run a timing check? Make sure you have the plug wires connected correctly

Mark helpful

F_O_R answered 3 years ago

Possible Northstar head gasket/head bolt failure.

1 people found this helpful.
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