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Ask Dave Nova Your Own Question
Dave Nova
Dave Nova, Chevrolet Technician
Category: Chevy
Satisfied Customers: 19452
Experience:  ASE Master Certification. GM World Class Certification
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2004 silverado 5.3 runs rough codes p0200&po300

Customer Question

2004 silverado 5.3 runs rough codes p0200&po300
Submitted: 6 years ago.
Category: Chevy
Expert:  Dave Nova replied 6 years ago.
Hello and thank you for using JustAnswer. My name is David and I will do my best to help you with your Chevy problem.

Is the engine misfiring while running at an idle?
Customer: replied 6 years ago.
yes , idles rough , started as intermittent.replaced plugs & wires,cleared codes,problem seemed to have gone away.3 days later it was back.also,has lack of power.
Expert:  Dave Nova replied 6 years ago.
The P0300 is a misfire code, the P0200 is an injector circuit fault.

With the engine running, use insulated pliers to remove the spark plug wire at the coil for each cylinder one at a time. The rpm should drop at each cylinder when this is done. If there is no rpm drop at one or more of the cylinders, check the injector wiring to the injector for that cylinder. If the wiring is intact, replace the injector.
Customer: replied 6 years ago.
just got freeze frame data.fuel system 1&2 OL-fault .is computer trying to compensate for bad injector?
Customer: replied 6 years ago.
just got freeze frame data.fuel system 1&2 OL-fault .is computer trying to compensate for bad injector? If i have a bad injector,why a "random" cylinder misfire & not a specific cylinder? are injector problems common in these vehicles with 123,000 miles and our friend ethanol in the gas ?
Expert:  Dave Nova replied 6 years ago.
It will try to compensate. Were there any codes other than the P0200 and the P0300?
Customer: replied 6 years ago.
no. those were only 2 codes.just went out to pull plug wires one at a time to locate dead cylinder, and of course now truck runs smooth.
Expert:  Dave Nova replied 6 years ago.
Try wiggling wiring harness at engine to see if you can make the engine miss again. Also move harness at drivers side front of engine compartment going to PCM.
Customer: replied 6 years ago.
sorry about not getting back sooner...working on other nightmares.no change while wiggling harness or connectors,although just wondering about freeze frame info ...customer complains about truck running REAL bad cold although i can clear codes and get them to return when fully warm.freeze frame info said fuel system 1&2 OL-failed . i did not get what temp it happened at. wondering if it set code while in open loop or if there is something causing it to go into open loop.
Expert:  Dave Nova replied 6 years ago.
With the injector fault code setting, this could force it back into open loop. Check the connectors at each of the injectors. Unplug and reconnect each of the connectors a few times. This will wipe away any possible minute corrosion on the terminals. Then clear codes and drive the truck to see if the problem returns. Let me know what you find.
Customer: replied 6 years ago.
oh yeah, didn't even have to drive it.a little brake torque to load it and it set p0200 code , with brakes applied in gear full throttle i get OL-drive let off throttle,goes right back to CL.
Expert:  Dave Nova replied 6 years ago.
Look at misfire data with engine loaded. See which cylinders are misfiring.