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GM Forum - Buick, Cadillac, Chev, Olds, GMC & Pontiac chat (https://www.gmforum.com/)
-   1992-1999 (https://www.gmforum.com/1992-1999-91/)
-   -   Code PO300 random misfires (https://www.gmforum.com/1992-1999-91/code-po300-random-misfires-310539/)

Adam_Tinkerer 09-25-2016 09:33 PM

Code PO300 random misfires
 
Having issues, especially driving up hills. First thing I did, changed upstream O2 sensor (was giving a code for that too), and replaced plugs w/Delco Iridiums. Didn't seem to help much, though less CEL. Changed the plug wires last weekend, wasn't sure of any improvement. But after a week, I'd say some improvement at least, but still getting this code. What to look at next?

Mad_Coachman 09-26-2016 07:29 AM

Check fuel pressure.....pump may be on it's way out.

2kg4u 09-26-2016 09:18 AM

Yup. Fuel pressure is next on the list.

Adam_Tinkerer 09-26-2016 10:42 PM

I haven't had a chance to change the fuel filter, so there's a possibility...

grandpabuick 09-28-2016 07:38 PM

misfire with load in overdrive, check coils.


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