where exactly do i pinch off and is the line rubbery at some point so i can pinch it?
Help, cylinder misfire, rough idle, significant power loss
- Thread starter JrsK1500
- Start date
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Dingo378
Newbie
Got propper compression in those cylinders? My 03 had two miss fires, checked everything and it turned out it was low compression, but if i jumped on it, shes stuter and fall on its face and after it got goin the other two cylinders would light.
Exactly what my truck feels like. but even when it seems like they all light up i don't think its all what the 5.7 has to offer. Simply because ive ran about 3 or 4 other ecsb gmt400s and i get beat every time. Yes im young and dumb but didn't we all go through that faze? I havent ran a compression test yet. Will soon though. Im pretty sure the truck has a little over 200k but the **** face that sold it to me had an aftermarket gauge cluster put in and when i got it it supposedly had 148k. How i found out is because they had the transmission and torque converter rebuilt and one of the prior service records state that it had like 202k miles and then a more recent service record stated that it had a little less than 148k.
WFO4X4
Banned
once you found that out you coulda gotten his ass big time for fraud.
About the odometer fraud or the misfire? I can't really say much on the fraud aside from go and talk to an attorney. If you haven't checked your fuel pressure with the the return line blocked, you should. If it holds with the line blocked, you have a faulty FPR, and should replace it. If it still falls off with the line blocked, you need to cap the main fuel line and check deadhead fuel pressure. Use a piece of fuel injection rated fuel line and four fuel injection line hose clamps, two on the line and two on your plug (the ceramic end of a spark plug works well). Cycle the key on and off a couple of times and see what your pressure is. Should be 80 to 100 psi and it should hold. If it doesn't get nearly that much pressure, or falls off quickly, then your pump is probably the culprit. If it holds, then either your FPR is leaking into the intake or you have a faulty injector poppet. This would be a good time to upgrade to the redesigned injection spider, but it's expensive, so that's your call. If you pull the upper intake and find the FPR dripping or it has a clean spot beneath it, then you have likely found your culprit. If not, then you'll need a scanner that can read the misfire counters and you'll have to run it down that way. When you pull the main injection harness off the motor, check for corrosion or bent pins on the connector, and be careful on reassembly.
Even if you find a fault during the fuel system test, I would still do a compression check before you disassemble anything. Pull the fuel pump and ecm fuses, wedge the throttle wide open, pull all the spark plugs, and spin the motor three or four times per test. If the numbers are good ( should be over 120 I think) and the difference between lowest and highest is not more than ten percent of the highest number, then it should be fine. If you find a low cylinder, squirt some oil into it and retest. If compression rises significantly, you have bad compression rings and need a rebuild.
Hope this helps.
overdrive327s10
Newbie
98 5.7 233,000. Getting code p306 going up long hills only. Light goes off after while symptoms go away once atop. Newgm pump 54psi koeo 62 run new gm spider and fuel filter all 150 miles on em. 3500 miles on intake gaskets msd coil livewires summit dist. 145 psi #6 165 psi #2 only ones i checked. Very small miss at idle faint. 5 year cap and rotor no noises mechanical. Checked w tech 2 said multiple misses across board 2-5 counts and thousands on 6. Swapped plugs n wires w other cyl no change. Runs great otherwise. Gets 17.6 mpg. Interstate. Starts fast 1/2 crank. No oil use still yellow after 3500 mile. No coolant loss. HELP! Hope its not burnt valve!
redneckrichie
Newbie
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I had the same problem with my truck same exact thing I ended up changing the whole distributor there is a marking.on it for the 8 cylinder engine make sure.its there at top dead center it might be around 15 to twenty degrees off. What I did was grinded the hold down on the distributor take it adjustable then hooked the scanner up to it and had my co worker watch the cam retard in it while keeping the idle over 1000 and I turned it clockwise when in positive degrees counter clockwise for negative degrees try to get it between 0 to 3 degrees positive and clear the code then drive it. If it comes back on try to adjust it more
overdrive327s10
Newbie
It was at -9 and now i got it to -3. Its driving me nuts. I dont want to keep throwing parts at it. Could it be the ignition module? Or the thing under the rotor?
ccreddell
I'm Awesome
P0306 is a misfire. I had the same thing. Changed the FP thinking the poppits werent getting enough pressure to get them off their seat-nope. Changed the whole intake manifold (because I found a low mileage one for free). Didnt mind that part because I figured doing the manifold gaskets was a good thing. That didnt help either. I finally got the coin together to put the updated spider in it, and it runs like new now. Still running stock dizzy. For now.
