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I have a 93 gmc z71. Its been running really weird. It has no acceleration and its been shaking bad at low speeds. All plugs, coil, distributor, rotor have been replaced. New computer as well. Used an obd1 and got a 72 and 81 code. Do these codes possibly have something to do with the engine problems? Couldn't find the codes online...please help! Need to get my baby back on the road!

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  • Cars & Trucks Master
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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

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SOURCE: engine stalling on a 2002 chevy tahoe z71

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

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SOURCE: 02 GMC Sierra 4.3 V6 P1345

Well that sounds like a tough one , But here is a site worth checking out . Several mechanics use this it to help out people like your self that are frustrated and are getting P #$%$# off ! Good luck

Posted on Mar 09, 2009

  • 1 Answer

SOURCE: 1991 GMC TBI 350 sierra stalls bad

Could be the TPI Sensor or it might be a touch out of timing.

Posted on Apr 23, 2009

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SOURCE: p300 engine code replaced coil,wire,control module

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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