misfiring under load. no codes
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?
On The Tree
Joined: Jan 2004
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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?
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...
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
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
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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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.
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Verdad Gallardo 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.
