misfiring under load. no codes
#1
misfiring under load. no codes
here is exactly what is going on. the car runs fine at all times idle,WOT,city driving, ect...except in overdrive at low rpms..1200-1600 if i lightly press the gas is starts busting up. sometimes pretty bad, sometimes you can barely notice.(doesnt matter engine temp).. it hasnt thrown a code yet. i first changed the plugs and plug wires with no luck. then i installed new o2 sensors. no luck there either. any suggestions?
#2
here is exactly what is going on. the car runs fine at all times idle,WOT,city driving, ect...except in overdrive at low rpms..1200-1600 if i lightly press the gas is starts busting up. sometimes pretty bad, sometimes you can barely notice.(doesnt matter engine temp).. it hasnt thrown a code yet. i first changed the plugs and plug wires with no luck. then i installed new o2 sensors. no luck there either. any suggestions?
#3
Are you sure it is misfiring?
Have you checked it with a techII to see live misfire data?
Have you made any other recent changes to the car?
I agree with a possible fuel filter issue...
Have you checked it with a techII to see live misfire data?
Have you made any other recent changes to the car?
I agree with a possible fuel filter issue...
#4
it has been a week and it still hasnt thrown a code. i havent done the fuel filter swap yet but i am tonight. as far as injectors, how would i go about cleaning? i think it may be a possibilty of MAF because earlier that day i cleaned and re oiled my k&n. i let it dry, went to the track 20 miles away, made one pass, left and drove another 50 miles around town. the misfire started as i was almost home from the trip. with that much driving with no issue until then i was doubtful of a bad MAF. now im not so sure. if it was fuel filter wouldnt i notice it at other rmps. once im over 1600 rpms in overdrive the "miss" clears up. i even took the valve covers off to check the rockers for lifter bleed off. everything seems fine. if its an injector clogged can a bottle of injector cleaner help, or should i remove them and inspect them? thanks...i did clean the maf..no luck
#5
it has been a week and it still hasnt thrown a code. i havent done the fuel filter swap yet but i am tonight. as far as injectors, how would i go about cleaning? i think it may be a possibilty of MAF because earlier that day i cleaned and re oiled my k&n. i let it dry, went to the track 20 miles away, made one pass, left and drove another 50 miles around town. the misfire started as i was almost home from the trip. with that much driving with no issue until then i was doubtful of a bad MAF. now im not so sure. if it was fuel filter wouldnt i notice it at other rmps. once im over 1600 rpms in overdrive the "miss" clears up. i even took the valve covers off to check the rockers for lifter bleed off. everything seems fine. if its an injector clogged can a bottle of injector cleaner help, or should i remove them and inspect them? thanks...i did clean the maf..no luck
I wish you the best of luck with it, I just spent 2 weeks tracking down misfires in my car...techII said it was cyl. 5, but after wasting lots of time looking for it, it turned out to be a broken valve spring on cyl. 4....go figure.
Thanks
Mike
#6
well, if you could use a techII to see what cylinder is misfiring, you could try moving injectors around to see if the misfire moves with it.
I wish you the best of luck with it, I just spent 2 weeks tracking down misfires in my car...techII said it was cyl. 5, but after wasting lots of time looking for it, it turned out to be a broken valve spring on cyl. 4....go figure.
Thanks
Mike
I wish you the best of luck with it, I just spent 2 weeks tracking down misfires in my car...techII said it was cyl. 5, but after wasting lots of time looking for it, it turned out to be a broken valve spring on cyl. 4....go figure.
Thanks
Mike
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#8
looks like its gonna be a fuel issue. i installed a gauge on the rail and im only getting 50 psi. then it goes to zero after the car sits for a little while. im gonna put the new filter/regulator on and see if that fixes it. if not guess the pump is on its way out.
#9
well i replaced the fuel filter/regulator. it was definitly clogged up somewhat. when i installed and cranked the car again i was getting the full 58 psi. instead of the previous 50 psi. also the pressure is still bleeding off to 0 psi, but now it is taking an hour to do so instead of 15 mins. the car is still misfiring under low rpm load. i assume the pump may be bad, a bad injector, or possibly the check valve between the tanks...however i dont believe the bad check valve would cause the misfire/studder.