Mechanics

WHAT TO DO TO FIX PO300 CODE

1999 GMC Jimmy

My 1999 jimmy is giving a po 300 code it runs very rough. Has new cap and rotor, the plugs and wires are less than a year old. Used a cigar to blow smoke into intake to check for vacuum leak found none. Freeze frame data showed stft bank one 13.5%ltft bank one 0% stft bank 2 12.8% ltft bank 2 0% what would my next option be and how would I go about it thanks for response gary
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GARY KRUEGER
September 26, 2012.



First, do a compression test to make sure the motor is good.

The 300 is a random missfire. It could be an injector but before we go there. Do the test

Roy

ASEMaster6371
Sep 26, 2012.
THE COMPRESSION TEST CHECKED OUT GOOD ON ALL 6 CYLINDERS
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Tiny
GARY KRUEGER
Sep 27, 2012.

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