How JustAnswer Works:
  • Ask an Expert
    Experts are full of valuable knowledge and are ready to help with any question. Credentials confirmed by a Fortune 500 verification firm.
  • Get a Professional Answer
    Via email, text message, or notification as you wait on our site.
    Ask follow up questions if you need to.
  • 100% Satisfaction Guarantee
    Rate the answer you receive.
Ask Dave Nova Your Own Question
Dave Nova
Dave Nova, Pontiac Technician
Category: Pontiac
Satisfied Customers: 19452
Experience:  ASE Master Certification. GM World Class Certification
Type Your Pontiac Question Here...
Dave Nova is online now
A new question is answered every 9 seconds

2003 Pontiac Grand Am 3.4L V6 P0300 Misfire code

Customer Question

2003 Pontiac Grand Am 3.4L V6 P0300 Misfire code
Submitted: 1 year ago.
Category: Pontiac
Expert:  Dave Nova replied 1 year ago.

Do you feel the engine misfiring when running? If so, is it more prevalent when idling or when under load (accelerating)?

Customer: replied 1 year ago.
Thanks for the response. I don't feel the engine misfiring when running/accelerating. Car runs well. It is slightly rough at idle. When cold, I need to hold @ 1500rpm for about 2 mins in order to keep idle.
Expert:  Dave Nova replied 1 year ago.

Sorry for the delayed response. Does the check engine light flash at idle? Have you done a compression test or tried to isolate the missing cylinder by pulling plug wires off one at a time with the engine idling?

Customer: replied 1 year ago.
Hello . No flashing of the Check Engine light. Need to purchase a compression tester. Will respond back with the results. Thanks for your help !
Expert:  Dave Nova replied 1 year ago.

You are welcome. Will look forward to the results of the compression test.

Customer: replied 1 year ago.
Compression test completed. Disconnected fuel relay and disconnected the plug wire at each ign coil for each cylinder test.
#1 - 100 (ran test on #1 3x to confirm this result) #2 - 145 #3 - 155 #4 - 140 #5 - 150 #6 - 135
Would the #1 compression result cause the P0300 code ?
Expert:  Dave Nova replied 1 year ago.

It could cause the misfire code. Since #1 and #4 are paired on the same coil, it can also cause a false trigger of the P0304 code.

Customer: replied 1 year ago.
Suggested next steps ?
Expert:  Dave Nova replied 1 year ago.

Do a wet compression test (squirt a little oil into the cylinder). You can also do a running compression test, just remove the schrader valve from the end of the compression tester hose. Test at least cylinder #1 and one of the stronger cylinders so we have a comparison.