p0300

[kyhunter89]

Drove truck 150 miles yesterday and bout 4 miles from home I felt a stumble for a 5 seconds, then it went away then came back, went away and now it stays.

Pulled codes and it says p0300, random cylinder misfire. So I started pulling plug wires and no change came from 1,2, and 4.

Havent changed nothing in a couple years other than the walbro 255 had unclipped itself from the fuel pump harness bout three weeks ago.

Thanks in advance for all help.

[blacstar]

what do you need help with... looks like you found something

[96/chevy/pu]

A little more info, what your vehicle profile, miles, everyday driver?

[kyhunter89]

Daily driver, 2000 silverado 4.8 4l60e, trutrac 3.73, descreened maf, p&p tb. Basically stock daily driver with all mods done over 50k miles ago.

Havent found nothing blacstar, the fuel pump issue was a few weeks ago and I fixed it and had have zero problems since. I think It a mechanical/sensor/part failure of some kind.

How can I check cam position sensor? What Would make it only miss on them three cylinders? Computer?

I've done a bit of googling and Several have had this problem but never post their fix.

[kewljay223]

i just had this issue the other day but i also had a p0200 along with it. i hooked up my scanner and could see that #8 had a TON of misfire counts. if you have a scanner with that capability, it will help narrow it down to which cylinders (on top of what you found). then i went to autozone and rented their noid light kit and sure enough, #8 injector plug was not getting power from pcm. so i would recomend the noid light to make sure you are getting power (both positive and negative) to the injectors. an easy thing to check is spark by pullling the plug and grounding it. make sure you got spark. also see if they are fouled to see if you have a deeper issue. if your getting spark then you know your coil packs are good. just start from the end and work your way back.

the solution to mine was simple and wont help you any but ill share anyway since you said nobody else shares the answers. lol i have bigger injectors so i have plug adapters. one of the pins in the adapter wasnt clipped all the way in when it was made so it pushed itself back out causing the injector to only have the positive 12v and no signal from the pcm controlling it. pushed the pin back in until it clicked and she been workin just fine since. might be something as simple as that for you too.

p.s. you might have a short between the injector wires in the harness causing the injector(s) to stay on or off at all times. might have to start tracing wires out. good luck

[farmtruc]

I'd check fuel and make sure that pump isn't giving u any issues. Fuel pressure.

Not every time but if it's a cam sensor the engine would have a random hard start. Extended crank. Or back fire during cranking.
Crank sensor. The truck would just die or not start. Or sometimes start; just had a truck in here last week.

Also there is almost always a performance related code for these.

Misfires can affect other cylinders.
Fuel pump will make the truck act like u described.

[Ray@NP]

have you put a scanner on your truck to see what cylinders are actually have a misfire? before throwing parts at your truck it would be a good idea to diagnose it correctly. it could be as simple as carbon tracking on the plugs