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 Pete Your Own Question
Pete, Pontiac Technician
Category: Pontiac
Satisfied Customers: 27095
Experience:  17 Years Pontiac Technician and training.
Type Your Pontiac Question Here...
Pete is online now
A new question is answered every 9 seconds

I have a 2004 grand am error p0303, misfire plug 3 i change

Customer Question

I have a 2004 grand am error p0303 , misfire plug 3 i change coil pack twice , change wires three times , change injector , change plug twice gapped at .060. Compression on cylinder 120pds . Checked others real close to the same . Can clear code and at idle runs good after it runs awhile and warms up sets code again . Checked plenium when i replaced injector was fine , took carb cleaner sprayed around intake ports wanting to see if i had a vaccum leak motor did not change speeds . Only thing i havent changed is pcm or ignition module . Put a spark tester on plug was fine .
Submitted: 8 months ago.
Category: Pontiac
Expert:  Pete replied 8 months ago.

Hi my name is ***** ***** I will be happy to assist with this today.In some cases I may need more info to assist better.I apologize for any delay.

Can you tell me what the compression was for the other cylinders compared to the #3 cylinder?

Were injector pulse signals tested at all?

Let me know so we can continue,thanks Pete.

Customer: replied 8 months ago.
Customer: replied 8 months ago.
120 on other cylinder cant test injector pulses
Expert:  Pete replied 8 months ago.

Do you have a scan tool that can be plugged in to monitor misfire signals at all?

Customer: replied 8 months ago.
Blue driver
Expert:  Pete replied 8 months ago.

O.k.,does it show cylinder 3 misfiring all of the time or only when cold or warm?

Customer: replied 8 months ago.
Misfires all the time reset will be back in 3 min
Expert:  Pete replied 8 months ago.

If your scan tool has the option for a crank shaft relearn perform this relearn as posted on the scan tool as it will walk you through it and see if this corrects the fault.I have in allot of cases corrected misfires on GM engines and after correcting it the misfire still showed up and had to do a crank relearn to allow the computer to reset the crank and cam correlation signals.If this is or was already tried and does not correct this (as this is the first step here) let me know so we can continue.

If more help is needed, use the reply tab to continue our conversation. If no further assistance is needed, kindly rate my service,your 5 star rating is appreciated.You can rate at any time and we can continue to work on your question as this will not close out your question.Keep in mind in some cases it can be difficult to fully diagnose or help repair your vehicle without seeing it and I work on delivering the best possible answer from what I see to work with.

Thanks Pete