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GM Tech (Cam)
GM Tech (Cam), Auto Service Tech
Category: Car
Satisfied Customers: 27667
Experience:  GM Grand Master Technician 2007. 11 years experience.
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engine light comes on i got the codes it said cyl missfire..same code

Customer Question

i have a 2006 hummer H2 the engine light comes on i got the codes it said cyl missfire etc i changed coilpacks plugs and wires now have same code and light any suggestions
Submitted: 4 years ago.
Category: Car
Expert:  GM Tech (Cam) replied 4 years ago.

Greetings and Welcome to Just answer.

Which cylinders are misfiring?

Customer: replied 4 years ago.
it said mutiple cyl misfire so i replaced all coil packs,plugs,wires, ran fine now light on again and same code p0300 multiple misfire
Expert:  GM Tech (Cam) replied 4 years ago.

The problem with these is that sets even if one is misfiring and you need a scan tool to determine which one. Possible issues are intake gaskets leaking, fuel system issues, just to name a few.

 

Customer: replied 4 years ago.
the motor runs fine doesn't appear intake gaskets are leaking tried changing gas cap same result
Expert:  GM Tech (Cam) replied 4 years ago.

An intake gasket leak would not be something you see, but something that you can tell by spraying carb cleaner or ether around it.

The gas Cap would not cause a misfire.

 

Customer: replied 4 years ago.
the key here is the motor is not skipping
Expert:  GM Tech (Cam) replied 4 years ago.

It may be missing at a time when you cannot feel it. ALmost every motor out there has an individual misfire every few seconds, but one only and you will not feel it.

 

Customer: replied 4 years ago.
to set off the engine light i thought it had to be electrical not mechanical so now i don't know what to think
Customer: replied 4 years ago.
also i already replaced everything related to a misfire ?
Expert:  GM Tech (Cam) replied 4 years ago.

You changed the coils, but there could be a cylinder head issue, injector, wiring, fuel supply, exhaust restrictions, mass air flow sensor, and the list goes on. The light is on because there is a misfire, and that can be caused by anything that prevents the engine from firing properly on the cylinder or cylinders in question.

 

Customer: replied 4 years ago.
why would the obd2 not pick up on this
Expert:  GM Tech (Cam) replied 4 years ago.

THe code reader? Because it is only that, a code reader. YOu need a scan tool to determine which cylinder is the issue.

 

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GM Tech (Cam)
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GM Grand Master Technician 2007. 11 years experience.