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HELP!!!! P0307 engine code?????

47K views 22 replies 8 participants last post by  BOATERBIL  
#1 ·
My 05 ccsb 5.3 threw a p0307 dtc so i replaced the plug, wire and coil and it is still doin it. it runs just fine i dont notice any difference in performance from when the light is off to when it is on. took to my mechanic and he said it isnt an injector cause that would usuallu throw a p0300 random misfire. i clear the codes and literally 10 miles of driving later it pops back on. im at a standstill right now cause i dont know WTF it is. PLEASE HELP!!! :suicide2:
 
#3 ·
It doesn't run bad or puke out at all with the light on. I lost an injector in my olds intrigue and it shuddered and shook way bad. I had the dealer work on my a/c and they took out my whole dash cause my evaporator went out. I'm wonderin if they didn't pinch a wire in the reassembly process
 
#6 ·
If this is on your NBS, the one in your sig, you have 8 injectors (1 per cylinder). If the injector for cylinder 7 were either not functioning or functioning improperly could cause the code. P0307 is Powertrain Misfire Cylinder 7; P for powertrain, 0300 series is misfires, 01 through 08 denotes the cylinder (could be higher for more cylinders).

There should be nothing under your dash that would have any effect on your engines controls. The ECM is under the hood and the engine harness, control side of it anyway, is all under the hood. If you have access to a scanner, you could see if the injector is working. Lots of things you could check to see if it is working even without GM specific access from something like a Tech II. You could compare short term and long term fuel trim from one bank to the other, or oxygen sensor readings bank to bank.

I would bet money that it is an injector. The reason the engine doesn't shudder or shake or die with a dead injector is the other seven cylinders are keeping it going. Was your Intrigue a TBI? If you lost an injector on TBI, you'd be losing about half the fueling depending on the setup and the failure.

Anyway, hope that works. You could always pull the injector and see if you smell fuel.
 
#7 ·
I believe my intrigue is mpfi but not 100% sure. I used a mechanics stethoscope placed on the injector and it was ticking just like the rest of them even under higher rpms. I also checked resistance across all 8 injectors and they all read between 13.9 and 14.1 ohms so I'm truely stumped. I honestly am feelin hesitant to buy a new injector incase that's not what it is. That 160$ I don't have
 
#8 ·
I would personaly recomend you use the ACDelco plug and especially if thats what you still have in the other cylinders. I asked about the ramp gauge because had you used the OE plug and checked the gap with one you could have damaged it, and that would cause yet another missfire. Further more, if you have anywhere near 80k+ miles, I feel replacing all 8 plugs with new ACDelco pieces would be money well spent since they are nearly due anyways.

In a returnless fuel system such as yours, ANY rust or contaminant in the fuel lines beyond the filter MUST go to your injectors. This was not the case in the past because much of the fuel that was pumped to the fuel rail got sent back to the tank via the regulator. This change in the flow path has prompted a TSB about rust/debris contaminating the screen of the injectors and necessitates replacement if it occurs.
 
#9 ·
Robert is right about the fuel flow. Just because the injector is ticking doesn't mean fuel is flowing through it. It could have rust from the lines built up, or varnish if the truck ever sat a long while or had bad gas.

Interestingly enough, though, NGK is one of two recommended brands for the LS series engines in GM trucks. NGK iridium and AC Delco platinum are what is recommended by All Data, at least for my truck. As for checking the gap, if you do not have a ramp gauge to check, don't. You are better off with a gap slightly large or slightly small than chipping off the electrode plating and wearing out the spark plug faster than it normally would.
 
#12 ·
It doesn't run bad or puke out at all with the light on. I lost an injector in my olds intrigue and it shuddered and shook way bad. I had the dealer work on my a/c and they took out my whole dash cause my evaporator went out. I'm wonderin if they didn't pinch a wire in the reassembly process
do a goggle search you can get your injectors rebuild or buy new ones a 4 a lot less.
Had same problem with my 2000 doge it was the fuel rails corroding clogging the injectors.starts with back ones first.
 
#19 ·
Care to enlighten the uneducated? I've never understood the point of moving far too much fuel around in circles, providing more complication, more parts to fail, and more fuel to leak/burn in a crash...plus it makes converting carbureted vehicles more work.
The only extra part a return fuel system has is a return pipe. The OP's truck has a regulator and filter built onto the pump so in essence it moves the same volume of fuel through the pump but makes repairs more costly because you cant change a $20 filter or $100 regulator when they fail like you could in the past. Converting to carb on a return system would only require a remote mount regulator with a return outlet instead of a single in and out regulator.
 
#20 ·
:hmm: I don't understand why a regulator and filter built-in to the pump are specific to a returnless system. So the GM system with that configuration sucks, but is that inherently required for a returnless system or could they be modular if it was designed better?

As for carbs, I was talking about converting a carbureted vehicle to fuel injection. I want to convert my 1980 Buick but I don't relish the thought of running a whole second fuel line back to the tank and drilling a hole in my tank (or buying an appropriate tank).
 
#21 ·
:hmm: I don't understand why a regulator and filter built-in to the pump are specific to a returnless system. So the GM system with that configuration sucks, but is that inherently required for a returnless system or could they be modular if it was designed better?

As for carbs, I was talking about converting a carbureted vehicle to fuel injection. I want to convert my 1980 Buick but I don't relish the thought of running a whole second fuel line back to the tank and drilling a hole in my tank (or buying an appropriate tank).
No i'm speaking strictly of GMT800 and GMT900 fuel systems. On your 80 Buick you could mount your regulator and fuel filter however you prefer. The OP's downfall was that the tiny flake of rust that got stuck in his injector might have been recylced to the tank and filtered out by the strainer or fuel filter had his truck been a return style system.