Fixing the dreaded P0300!!!!
November 13th, 2014, 3:48 PM
#12
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Comp test shows 170-180# across all 8 cylinders! sweet! moved plugs around to rule out a faulty plug. Misfire is still on #3. grounding the plug on the block I see a good spark so plug wire is OK. The misfire is at idle and while driving, if I clear the code it returns in 3-5 minutes engine warm or cold. as far as fuel pressure KOEO it's right at 60# and stays there for close to an hour after key off (new fuel pressure regulator seems to be working) before the Fuel Pressure would drop immediately after key off. next I'm gonna pull the valve cover and inspect rockers and rods... Thanks guys
November 13th, 2014, 4:21 PM
#13
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Sounds like you are making progress and the solid fuel pressure is a good sign as is the compression...
Moving the plugs was a good move now how about the wires?
Moving the plugs was a good move now how about the wires?
November 13th, 2014, 7:02 PM
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wires I assume are good. used old one and new one both to verify the spark was getting to the plug. checked that by laying the plug on the manifold and watching the spark as I turned her over.
All I can think of now is maybe the poppet injector is stuck open...
A push rod bent/lobe on the cam flattened, isn't allowing the combustion process to happen in a timed fashion...
one of the 2 on left bank (guessing 2nd one), O2 sensors is telling the CPU to pump in more fuel than it needs based on a faulty reading from the sensor...
After those are checked i'll scrap her and buy early carbed bowtie pickup
All I can think of now is maybe the poppet injector is stuck open...
A push rod bent/lobe on the cam flattened, isn't allowing the combustion process to happen in a timed fashion...
one of the 2 on left bank (guessing 2nd one), O2 sensors is telling the CPU to pump in more fuel than it needs based on a faulty reading from the sensor...
After those are checked i'll scrap her and buy early carbed bowtie pickup
November 13th, 2014, 8:59 PM
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November 13th, 2014, 9:22 PM
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If you are having the miss on one bank as in cyl 3,5,7,1 and you have checked for vacume leaks. replace the o2 on that side or if you want to test, switch the o2s and in ban1 sens1 with ban2 sens 1 and vice versa. I suspect you have a faulty o2 (bank 1 , sens 1) I have seen this a few times now.
November 14th, 2014, 4:03 PM
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If you are having the miss on one bank as in cyl 3,5,7,1 and you have checked for vacume leaks. replace the o2 on that side or if you want to test, switch the o2s and in ban1 sens1 with ban2 sens 1 and vice versa. I suspect you have a faulty o2 (bank 1 , sens 1) I have seen this a few times now.
would a faulty sensor tell the computer to add/restrict fuel usage by the engine, and if so why would it only be on #3 as opposed to the whole left bank?
I pulled valve cover, rockers, push rods... rocker wear patterns are nice and glassy smooth in the right positions. rods are straight n true (rolled them on glass to look for little bends) all the little oil ports are free n clear and the lifters move freely. mechanically it seems OK. Can't rule out a flattened lobe because I didn't see them but everything else in the valve train seems to be in order so I assume the lobes are as well.
That leave me with fuel...
And yes, thank you I'm aware of P Curve, but how would I even begin to test for that? new spark plugs are showing some sign of firing after pulled and checked several times in #3 so I have to imagine the spark is happening in the cylinder as a result, right?
November 14th, 2014, 6:56 PM
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would a faulty sensor tell the computer to add/restrict fuel usage by the engine, and if so why would it only be on #3 as opposed to the whole left bank?
I pulled valve cover, rockers, push rods... rocker wear patterns are nice and glassy smooth in the right positions. rods are straight n true (rolled them on glass to look for little bends) all the little oil ports are free n clear and the lifters move freely. mechanically it seems OK. Can't rule out a flattened lobe because I didn't see them but everything else in the valve train seems to be in order so I assume the lobes are as well.
That leave me with fuel...
And yes, thank you I'm aware of P Curve, but how would I even begin to test for that? new spark plugs are showing some sign of firing after pulled and checked several times in #3 so I have to imagine the spark is happening in the cylinder as a result, right?
I pulled valve cover, rockers, push rods... rocker wear patterns are nice and glassy smooth in the right positions. rods are straight n true (rolled them on glass to look for little bends) all the little oil ports are free n clear and the lifters move freely. mechanically it seems OK. Can't rule out a flattened lobe because I didn't see them but everything else in the valve train seems to be in order so I assume the lobes are as well.
That leave me with fuel...
And yes, thank you I'm aware of P Curve, but how would I even begin to test for that? new spark plugs are showing some sign of firing after pulled and checked several times in #3 so I have to imagine the spark is happening in the cylinder as a result, right?
November 18th, 2014, 3:04 PM
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I give up! I got no other leads to go on. pulled the spider again and the injector was clean as a whistle after the seafoam treatment. she has spark, great compression, fuel pressure is steady, valve train looks good. Still a misfire on #3 per the code but she idles and drives fine now. reflash the computer???