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04 Impala with engine misfire have code


2000Lumina

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I drove the car home parked it, next day I start it up it's missing and the check engine light is on. I hooked up my scanner and got code PO300B engine misfire detected under PCM. I didn't get a coil pack number or a cylinder number. Any suggestions? Thanks

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A po300 doesn't necessarily mean it's only an ign related issue....

source could be fuel system related, also could be a mechanical issue.......

clear the codes, see if the code reappears,

read this article on the subject,

https://troubleshootmyvehicle.com/gm/3.8L/troubleshooting-misfire-codes-1

is this a high mileage vehicle?

 

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On 8/22/2020 at 8:26 PM, 2000Lumina said:

I drove the car home parked it, next day I start it up it's missing and the check engine light is on. I hooked up my scanner and got code PO300B engine misfire detected under PCM. I didn't get a coil pack number or a cylinder number. Any suggestions? Thanks

1. Never heard of "P0300B".  Gonna have to research that.

2.  Does your scan tool read manufacturer-specific codes, or just generic codes?  P0300 is a hateful code, I almost always hear about that one from folks with cheap scan tools.  The cheap tools often don't report the REAL code, they report the generic code, which doesn't tell you which cylinder is actually misfiring.  In other words, you might actually have "P0304", misfire on #4, but the scan tool lies to you by saying it's "random".  Truly "random" misfire is possible...but it's more likely you have misfire in specific cylinder(s); if you knew which one(s) you'd be time and money ahead to just investigate the ones actually misfiring.

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Jim_rockford_007

if the tune up parts are KNOWN to be good, then you need to investigate the intake gaskets . having a bad intake port seal will cause the cylinder to run lean or even suck in oil  causing a misfire. 

 

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