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Discussion Starter #1
so i been having a intermittent misfire i done the usual new plugs new boots changed the coils around as well as the injectors and the fuel filter. the fuel pressure stays steady at 30 psi even when its missing and i have looked for vacuum leaks and there is none and i did a compression and leak down test and it came out good.:mad:

so now im thinking its some electrical problem as it happens in cylinder 3 and 4. now what im trying to figure out is what electrical components will cause a misfire on those 2 cylinders? and how to test them
 

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not that's your problem, but isn't 30psi a bit low for our cars? Thought it was supposed to be around/above 40psi.....
 

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Discussion Starter #5
you might be right:dunno i thought it was 30 psi tho i got to search around and find the correct number
 

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how many miles are on the car?
 

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so i been having a intermittent misfire i done the usual new plugs new boots changed the coils around as well as the injectors and the fuel filter. the fuel pressure stays steady at 30 psi even when its missing and i have looked for vacuum leaks and there is none and i did a compression and leak down test and it came out good.:mad:

so now im thinking its some electrical problem as it happens in cylinder 3 and 4. now what im trying to figure out is what electrical components will cause a misfire on those 2 cylinders? and how to test them
Any codes? You have access to a scanner?
 

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Discussion Starter #11
well thats what the computer picks up 99% of the time i dont get a cel ill look at the fuel trims later on.
 

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If you have changed the plugs and switched the coils/injectors to other cylinders and still get the occasional misfire on those two cylinders, you might have a problem with your injector or coil connectors to the main engine harness. I have seen intermittent misfires simply because the female pin connectors were widened and had a bad connection at times.

I still want to see what your fuel trims are doing. That will help us isolate whether it is fuel or spark related and where to look next.
 

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how many miles on the car
 

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Discussion Starter #14 (Edited)
it has 129k heres an old freeze frame from a couple months ago the only thing i have change since then are all four O2 sensors but it was the same issues as right now
 

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Not sure if this helps but your fuel trims are way off bank to bank. It could be from the motor not getting warmed up. Also not getting staying in closed loop comes from a vac leak, bad/dirty maf, or bad injecter. Have you tried swapping your injecters and coils from bank to bank to see if you can get your trouble code to move cylinders?
 

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Discussion Starter #17
so i checked the fuel trims when i had a chance they were on bank one .99 and 1 on bank two. i got those reading by briefly starting the car up i will get reading hopefully tomorrow after i have a chance to drive it.
 

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it has 129k heres an old freeze frame from a couple months ago the only thing i have change since then are all four O2 sensors but it was the same issues as right now
Those fuel trims aren't crazy off, plus your car wasn't completely warm. Get that car all the way up to operating temp and datalog your fuel pressure and fuel trims. The trims in that freeze frame are a bit off, but they are off on the wrong bank. Bank 1 looks good, which is where you are having problems. According to that, it looks like fuel probably isn't your problem, but I'd still like to see it at full temp. If it were a lean misfire caused by low fuel pressure, you would have basically pegged fuel trims on bank 1 for long term and short term because your car would be trying to add as much fuel as possible. Do you have access to a scope or graphing multimeter?
 

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no i don't have access to any of them
Well, if you have honestly replaced the plugs (gapped correctly), changed the coils and injectors around, fuel trims are good on that side, and it is still intermittently having problems only on #3 and #4......we are running out of possibilities quickly. How many times have you pulled the plug "wires" or connectors? My money is on a bent or widened pin in either of those two connectors causing the intermittent problem. Your other possibilities are the harness itself or the PCM.
 
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