Misfire, running out of ideas.
#1
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So as some of you know i developed a nasty inconsistent missfire the other day. I have already changed my plugs (autolite 3923's) and my cap and rotor. Still no improvement. So today i did a compression test and got 175-190 on all 8. I also check fuel pressure and holding a steady 49 psi. I swapped out my coil for a spare one i had and no change. I have just about run out of ideas. The only thing i havent tried is driving around with the fuel pressure gauge to see if it cuts out.
I would think that if i had a broken valve spring that the miss would be constant and that if the dizzy shaft gear was worn then it would run like **** all the time if it would run at all.
My plenum does appear to be leaking a little bit but no pools of oil in there. I do hear a noise when it misses that almost sounds like a ping, but its not loud enough to be certain. I guess i can pull the o2 sensor and see if thats helps but i dont see any of the clogged cat symptons.
I would think that if i had a broken valve spring that the miss would be constant and that if the dizzy shaft gear was worn then it would run like **** all the time if it would run at all.
My plenum does appear to be leaking a little bit but no pools of oil in there. I do hear a noise when it misses that almost sounds like a ping, but its not loud enough to be certain. I guess i can pull the o2 sensor and see if thats helps but i dont see any of the clogged cat symptons.
#2
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Sounds like you should try the o2 thing. Can't hurt at least.
Also check your Plug wires thoroughly. I had a misfire appear out of nowhere in my '95 not long ago. It was so bad I thought I blew a head gasket and lost compression in one cylinder or something. Turned out to be a plug wire arcing out on the exhaust manifold.
Also check your Plug wires thoroughly. I had a misfire appear out of nowhere in my '95 not long ago. It was so bad I thought I blew a head gasket and lost compression in one cylinder or something. Turned out to be a plug wire arcing out on the exhaust manifold.
#4
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yeah tonight im going to mist everything down with water and run it to see if i see any "lightning". The only other thing i can think off is maybe my injectors are dirty or a leaking brake booster, but my brakes seem to operate just fine and i dont hear a leak.
Ohh an BTW it only seems to do it with a load on it. It may be doing it in park or nuetral but its to light to tell. Also when I changed the plugs they were all clean, no residue, so my plenum is not leaking very bad at all. And if i had a broken valve spring, cracked valve seat, or a sticking valve the compression test would have shown it right? or do i need to do a leakdown test?
Ohh an BTW it only seems to do it with a load on it. It may be doing it in park or nuetral but its to light to tell. Also when I changed the plugs they were all clean, no residue, so my plenum is not leaking very bad at all. And if i had a broken valve spring, cracked valve seat, or a sticking valve the compression test would have shown it right? or do i need to do a leakdown test?
Last edited by QuadCabLuv; 02-02-2013 at 03:30 PM.
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#9
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So i pulled a sample of fuel from my truck and its pretty yellow. looks a bit like mountain dew. So i hoping that this is all just bad gas. I took it on a short drive and ran it kinda hard and it was definitely pinging which will happen with bad gas. I wont know for sure though until i get some fresh gas. at least i only have 1/4 tank in it now.
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