I HAVEA 2006 ENVOY TAHT GAVE ME P0301. I CHANGED ALL SPARK PLUGS, WIRES COIL FOR CYLINDER 1 ONE AS WELL *** THE INJECTOR. AFTER TAHT WAS ALL DONE IT GAVE ME CODE P0300. THINGS TAHT HAVE BEEN CHECKED. PUT IN SMOKE FOR LEAKS AND NO LEAKS, CLEANED THROTTEL BODY AND MASS FLOW S. CAR STILL IDLING BUT NOT AS BAD AS IT WAS AT FIRST. PLEASE HELP
The I6 engine is tricky. Make triple sure the boots on the coils are seated properly on top of AC Delco 41-103's only. This engine loves those plugs, as others have been known to mis-fire. I would start with engine running, try unpluging just the wire at the coil at each cylinder. The cylinder you unplug that has no change in idle would be your culprit. Hope you disconnected the battery after cleaning the throttle body, if not, will idle bad. If you didn't, unplug fuses #10 and #28 under the hood for a 1/2 hour, this will reset the pcm.
With as many sensors as that thing has, go to Autozone and ask for a free diagnostic tool check.
SOURCE: p0300 code still cominng up on my scanner anthe
I don't think it could be the injectors. Because, all of them would have to go bad at the same time to give you code P0300. If one injector when bad on number one cylinder, it would give you a code of P0301 for cylinder #1 misfire. Code P0300 is the computer simply can't determine the specific cylinder of misfire. Basically,
I would look at the EGR system, engine timing, and fuel pressure. One of these should be the source of the problem.
SOURCE: i have a 2000 gmc sierra 5.3 with a number 6
I would check the valves for number 6. If one or both are burned, stuck or out of adjustment it would cause your problem. If a cam lobe for that cylinder is burned or badly worn it could be the culprit.
SOURCE: Code P0121 on 2006 GMC
Classic signs of idle air control not able to cope with sudden engine loads. Cleaning should resolve this. Remove ducting from air cleaner to throttle entrance. Spray with carb. choke cleaner or WD40 spray and wipe back to the alloy finish. clean the the throttle plate and push the throttle open with your fingers and clean in behind as best you can. Clean the passageways to the idle air control valve. Remove the valve and give it a thorough clean up. Reassemble and it should all be good.
SOURCE: Code P0121 on 2006 GMC Envoy Denali Check eng.
Cleaning the throttle body is certainly the right thing to try first. Make sure you clean the throttle plate as well.
Testimonial: "Thanks. It seems to have worked."
SOURCE: I have a 2003 GMC Savana van. It is missing at an
Have you tried looking at the intake manifold gasket? at idle it will misfire, under higher engine speeds it will go away. Also look for a vacuum pipe split/perished. I use brief bursts of brake cleaner to find manifold airleaks around the joint between the manifold and engine block. If you attempt this please be careful. The engine speed will rise if a leak is present, showing the leak. Brake cleaner is also very flammable and toxic. Be sure to do this in a well ventilated area. A fire extinguisher might be a good choice too. You can never be TOO SAFE. I've been doing it for years without incident. If you need more clarification, leave a post... Hope this helps.
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