p3000 code

Oilerman1957 · Dec 30, 2009

My van is throwing out a p300 code, I have replaced plugs, wires, distributor cap and rotor, fuel pump. Still getting code. Took to GM dealer they say random misfire on 3 and 5 cylinder with #1 missing sometimes. They replaced gear in distributor that goes to cam.{forgive me if im not exact} Van runs good, you cant even feel the misfire, it wouldnt start a few times but then would start next day. Keeps getting check engine light but sometimes it even goes out.Check engine light seems to only come on when starting and has a few times just idling never when driving. Dealer is lost. Oh its a 4.3 engine, vortec v-6

greg334 · Dec 30, 2009

Get another dealer.

They are missing a lot of things, maybe the MAP sensor or the crank sensor but how can they tell if it is missing on a specific cylinder when they can't figure out what other problems it could be.

The cam drive gear? I haven't heard that one before.

Oilerman1957 · Dec 30, 2009

I dont know greg, they were trying to get me to replace all fuel injectors or they said it might need a new engine, i just laughed and said i would be in to pick the van up. That p300 code can mean so many different things i was hoping someone on here has been through it before

Moot · Dec 30, 2009

Try this link to GM's on-line question and answer service.

Online GMC Mechanics Answer Service & Repair Questions on Sierra, Canyon, Acadia, Yukon, Envoy, Savana, Sonoma, Jimmy, TopKick, Denali and Hybrid Lines, all Makes and Models

greg334 · Dec 30, 2009

Well it could very well be a sensor failure, like the crank position sensor or if there is a cam sensor - both have something to do with the timing of the spark and the fuel delivery. Both can give a miss fire and because I don't know if the engine is a wasted spark system, if the ECM is thinking that the timing needs to be corrected and just fires off a spark at the wrong time - cam sensor issue.

The problem is that the problem needs troubleshooting that seems to be beyond the capabilities of the mechanic/service manager.

Oilerman1957 · Dec 30, 2009

Moot, the p300 code is such a random code it could be many different things, hell ive had 2 different mechanics look so far and there still scratching there heads

Oilerman1957 · Dec 30, 2009

greg334 said:
Well it could very well be a sensor failure, like the crank position sensor or if there is a cam sensor - both have something to do with the timing of the spark and the fuel delivery. Both can give a miss fire and because I don't know if the engine is a wasted spark system, if the ECM is thinking that the timing needs to be corrected and just fires off a spark at the wrong time - cam sensor issue.

The problem is that the problem needs troubleshooting that seems to be beyond the capabilities of the mechanic/service manager.

But wouldnt these throw off there own code greg? I dont know

greg334 · Dec 30, 2009

Not really because the p0300 is a misfire detected not a sensor out of range.

Oilerman1957 · Dec 30, 2009

Greg, talked to dealer and they said there was a lean fuel condition also, can sensors do that?

greg334 · Dec 30, 2009

Oilerman1957 said:
Greg, talked to dealer and they said there was a lean fuel condition also, can sensors do that?

Yea, it can - map/air flow sensor could be a problem but they should be able to ID it quickly.

Oilerman1957 · Dec 30, 2009

I dont think they know what they are doing, im picking van up tomorrow and will try some of your thoughts, anyway to be able to check those sensors first without replacing?

jezzy · Feb 18, 2010

had same problem with a 6.0 motor it was a pushrod. 183,000 miles. got new motor for it cheaper.

aukinet · Feb 18, 2010

Its being a GM Vehicle, the first thing that should be checked is the fuel pressure. These do wear out distributor gears so don't feel bad about that. Condition of plugs & wires? Compression? MAF sensor? Still, I would expect that the fuel pressure is not up to snuff. Plugged fuel filter?, Corroded pump connections? Bad pump? This would explain the codes, the no start, the lean condition.