Mechanics

C02 AND RANDOM MISFIRE

2003 Saturn Ion • 4 cylinder 2WD Manual • 175,000 miles

Car running badly and stalling. Ran code reader- codes 137, 141 and 0300. Replace O2 sensor #2. Still get random misfire and engine light came on after erasing codes. Ran code reader again, code 0300. What could it be? What causes random misfire?
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Pfootmom
November 28, 2010.




Random misfire is usually caused by vacuum leaks and bad fuel.

Tiny
Rasmataz
Nov 28, 2010.
Thanks. The car doesn't appear to have many vacuum lines but I will check again.

Tiny
Pfootmom
Nov 28, 2010.
In addition to random misfire, the timing is advanced to 37 degrees at 2500 rpm - what is this?
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Tiny
Pfootmom
Nov 30, 2010.

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