itibitiguy

hey everyone

i recently got a 03 chevy silverado 3500, all was fine the i start getting the blinking engine light on evening on the way home, it went away some i didn't think much of it.... the next couple of day is starts getting worst and worst, now it does it all the time. So i mechanic buddy was headed out of town, he dropped off the code reader and checked what codes. There were p0300 code, and coil "A" and coil "H", and O2 sensor and mass airflow code.
So we cleared the codes and went for a run in the truck, all that came back up was p0300. we check all the wire and plug connections (new wires and good connections) so he said "try new plugs first"

So today that's what i done, got new plug (ac delco) and made sure they were gapped right (0.040) got them in and took the truck for a run, and right away the engine light is flashing and there's a lack of power in the truck. When i read the codes i get

p0300 (pd) random/multiple

and

Cylinder Misfire Detected

ive read that maybe to get a relearn done? Any Ideas?

Thanks
joe
princeton landscaping .ca

itibitiguy

Still tryin to figure out my problem... i drove it for work yesterday and put some fuel injector cleaner in. still nothing... when i changed the plugs.. there was a stink of gas when i changed the passeneger side middle two plugs. So my friend said "switch the coils of the 2 plug that stunk like gas and move them to the other side, take the truck for a run, and then check if those plugs that you moved the coils to stink like gas"

so i done it and when i check the plugs, none of them stunk like gas,,,

Really need some help on this one, its my work truck and i don't work if it don't.

ajparry89

wow i just posted a new thread for a similiar issue, only with a 1500 4.3L ive done lots of reading up on other forums, this code seems to be a tough one to always pin point. things id recommend checking on yours is the fuel pressue, and the distributor. for the 4.3L there was a bulletin for the distributor (didnt fix my issue though, of course lol). also, check compression for each cylinder. check for vacuum leaks as well.

bobbby

I have the same problem with my 07 Silverado 4.8 with only 70,000.miles I changed the plugs and wires and coil pak can some one please help

itibitiguy

so i put my truck in the garage to fix the misfire. All the spark checked out good (plugs/wire/coils) the PVC valve was gone, but it didn't fix the problem... next is fuel, so the truck has 51 psi (on the fuel rail im guessing) and when it gets under load, it drops to 21 psi.... so check and switch the fuel filter.... it was dirty but even with the new one its still misfiring.... So im now waiting on a new fuel pump to be flown from moncton to st. john's. Hoping this fixes my problem, and may be some help to some of you guys... ill update once the fuel pump is in

ajparry89

Hope it works out for you! that is definitely low fuel pressure, maybe also the fuel regulator, who knows. fuel pump wont fix mine i dont think..i got good fuel pressure

67Motorcat

Fuel pump is dieing a slow death....It can't keep up with the demand(pressure drops) as RPM's increase and the ECM freaks out and throws codes.

Pretty typical for the age and mileage you describe.
Replace it as suggested and your good to go for another 100K miles or so.

itibitiguy

so back fro the garage..... new fuel pump put it still getting misfire .... pulled out the o2 sensors to see if the Cats were plugged, still the same, new O2 sensors. They said its still getting the misfire on the back to cylinders. removed the fuel rails and check'd them. both were okay, switched injector 7 with 3 and still getting the misfire on the back 2 cylinders (#7 and 8 cylinders)
Got him to do a relearn for the crank sensor, still the same misfire. Basically everything has be checked. Lots of compression, spark is good, fuel is good. no vacuum leaks on the intake. So at this point he figures its the ECM and for that i have to get it programmed at GM when the new ECM goes in. Im in real need of some help with this ECM.
Can i get a used one? or am i better off getting a new one?
Can i use my truck if i put in another ECM without getting it reprogrammed?

Again any help would be appreciated greatly as this is my work truck which i need for work

joe

MDTAHOE

What size is the engine? It would be highly unlikely that the problem is the ECM. I have never had to replace a GM truck computer. You need to find someone that has a 4 or 5 gas analyzer to check the tail pipe emissions. By checking that it can be narrowed down to an ignition or a fuel delivery issue.

itibitiguy

its a 6.o liter