Question about Cars & Trucks
I'm showing code 72 as being a problem with the vehicle speed sensor, and code 81 as a 2nd - 3rd shift error in the transmission.
Have you replaced the plug wires, and checked the base fuel pressure ?
Posted on May 05, 2013
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Posted on Jan 02, 2017
Still sounds like a fuel problem. Try a full tank of supreme gas, plus put a can of SEAFOAM into the tank to help clean you injectors. See if this will help clear up your problem. Did you change the plugwires????
Posted on Feb 08, 2009
SOURCE: 02 GMC Sierra 4.3 V6 P1345
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Posted on Mar 09, 2009
P300 reads as: 'random/multiple misfire' which usually means all cylinders are misfiring intermittently. Suspect a defective crankshaft/camshaft position sensor or weak fuel system pressure. If only one cylinder is misfiring (check by sliding a test light probe [make sure the ground lead is clipped to the engine securely] between each plug wire boot and it's wire at the distributor/coil block to short out that cylinder's spark. The dead cylinder will not change when it's spark is killed. Try a new spark plug first, then test that cylinder's compression if no help. You could have a bad valve. If the old plug was wet with fuel, the injector is probably doing it's job. When this cylinder runs again, that may clear up the backfire problem. Hope this helps!
Posted on Apr 04, 2010
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