2003 Chevy Avalanche PO300 MISSFIRE CODE

ROBINSLACK

MEMBER
2003 CHEVROLET AVALANCHE

Engine Mechanical problem
2003 Chevy Avalanche V8 Two Wheel Drive Automatic

i am getting a po300 missfire code, and have no fire to cylinders 1, 3, 5, 7, the cylinders are firing, but are missfires

Sunday, May 9th, 2010 AT 8:44 PM

2 Replies

RASMATAZ

MECHANIC
75,992 POSTS

Engine running rough or misfiring can be cause by the following:

1. Defective spark plug.
2. Inadequate spark/coil, defective spark plug wire.
3. Lack of compression
4. False air leakage.
5. Faulty fuel injectors.
6. Insufficient fuel pressure.
7. Contaminated fuel.
8. EGR valve that is leaking.
9. Oxygen sensors.

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Sunday, May 9th, 2010 AT 10:25 PM

ROBINSLACK

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2 POSTS

We have done a compression check, changed mas sensor, map sensor, new pulgs, checked oxygen sensor, still missfiring and running lean, all the problems started when I was going down the interstate, and put the truck on cruise control, could my electronic trhottle body be the culprit.

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Saturday, May 15th, 2010 AT 11:30 AM