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Ask GM Tech (Cam) Your Own Question
GM Tech (Cam)
GM Tech (Cam), GMC Mechanic
Category: GM
Satisfied Customers: 5787
Experience:  GM Grand Master Technician 2007. 14 years experience.
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Hummer 2006 started missing and no power, changed plugs and

Customer Question

hummer 2006 started missing and no power, changed plugs and wires no improvement put a new mass airflow sensor still didn't help. So tried seafoam made it worse so changed plugs different type , driver side bank ok passenger side fouled black in color. Starts and idles ok has exhaust manifold leak now. Help
JA: Thanks. Can you give me any more details about your issue?
Customer: Code comeso up multiple misfire p300
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Submitted: 1 year ago.
Category: GM
Expert:  Greg replied 1 year ago.

Hi Just the P0300 code ?

What tool are you using to check for codes .

Will you be doing the repairs if yes do you have the following tools .

Fuel pressure tester .

Compression tester .

Tool with live date ,

Rgds Greg

Customer: replied 1 year ago.
Actronc p9135 obd I I autoscanner
Customer: replied 1 year ago.
Only the p300
Expert:  Greg replied 1 year ago.

Okay what i suggest you do first is a fuel pressure test as the P0300 is for multiply misfire meaning all cylinders are misfiring .

Can you do a fuel pressure test .