backfire under acceleration
#1
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backfire under acceleration
what can cause WOT accel backfire .. in all gears ( neutral included ) .. not boost level dependent .. rpm ~ 6.5K ... A/F ( innovate LC-1 digital ) dont go under 10.5 .. over 14.... ... egts normal
i floor it .. it revs..boost..pulls great .. gets to 6.5k .. backfires under WOT .. hesitates a split second .. and continues to rev ( i lose a bit of boost ) but will continue to rev ... sometimes back fires 2wice
i have had this problem for a while now and everything seems fine
new plugs ( 9`s )
wires
rewired ignition coils to igniter ( new power and signal wires )
upgraded fuel pump , rewired straight from batt
relocated + rewired knock sensor to rear housing
injectors cleaned + flow tested
stock ecu ,
idles great .. starts cold warm whenever .. never floods ..
upgraded inter cooler intake exhaust ...
only CEl i have is for the speed sensor .. i cut the wire going to the ecu so i can go over 180 km/h ..
hypothetically speaking .. backfire is unburnt fuel .. or excessive fuel ... unburnt ... but should this not show up on my a/f as an ... <10
any ideas , suggestion would be much appreciated
i floor it .. it revs..boost..pulls great .. gets to 6.5k .. backfires under WOT .. hesitates a split second .. and continues to rev ( i lose a bit of boost ) but will continue to rev ... sometimes back fires 2wice
i have had this problem for a while now and everything seems fine
new plugs ( 9`s )
wires
rewired ignition coils to igniter ( new power and signal wires )
upgraded fuel pump , rewired straight from batt
relocated + rewired knock sensor to rear housing
injectors cleaned + flow tested
stock ecu ,
idles great .. starts cold warm whenever .. never floods ..
upgraded inter cooler intake exhaust ...
only CEl i have is for the speed sensor .. i cut the wire going to the ecu so i can go over 180 km/h ..
hypothetically speaking .. backfire is unburnt fuel .. or excessive fuel ... unburnt ... but should this not show up on my a/f as an ... <10
any ideas , suggestion would be much appreciated
#3
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Have you messed with the ignition set up at all lately? I left off a connector on the coil packs while putting everything back together a few years ago and it had similar reasults as you. Maybe plug wires are bad, or loose?
What boost levels are you running? Why did you cut the speed sensor wire?
What boost levels are you running? Why did you cut the speed sensor wire?
#4
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i have tried .. 3 leading coils .. and i have the same result ... and nothing is unplugged or loose
boost is 10 psi ... it`s not boost cut im experiencing ..because i get the same wot backfire in neutral ... if i rev to redline... it`s just rpm dependent .. not boost / load
so weird
boost is 10 psi ... it`s not boost cut im experiencing ..because i get the same wot backfire in neutral ... if i rev to redline... it`s just rpm dependent .. not boost / load
so weird
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map connected ... grounds are clean + then some
same hesitation in neutral .. as under load ... it`s ONLY RPM dependent .. ~6.2-.3-.4-.5 K
i dont have another MAP to ..try..but for example i can rev in all gears under full boost up to 6k and no problem ... it pulls really hard .. good A/F and EGT ... boost 10psi
it just does not like going over 6K
same hesitation in neutral .. as under load ... it`s ONLY RPM dependent .. ~6.2-.3-.4-.5 K
i dont have another MAP to ..try..but for example i can rev in all gears under full boost up to 6k and no problem ... it pulls really hard .. good A/F and EGT ... boost 10psi
it just does not like going over 6K
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#12
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stock ECU .. stock injectors ... cleaned / flow tested
walbor 255 rewired to battery with relay ....
plug`s all 9`s ...
ignition coils rewired .. new signal wires from ignitor .. new power wires ( did this to try to cure this break up )
relocated + rewired knock sensor to rear housing
walbor 255 rewired to battery with relay ....
plug`s all 9`s ...
ignition coils rewired .. new signal wires from ignitor .. new power wires ( did this to try to cure this break up )
relocated + rewired knock sensor to rear housing
#13
RX-7 Bad Ass
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Have you replaced the coil pack harness? I know you rewired the coils to the ignitor, but there's a harness that goes from the coil pack to the connector behind the power steering pump stock. It's about a 1-foot harness, has all the plugs for the coil packs. If the harness has a ground wire, it's the old style coil pack harness - the new updated part doesn't have that ground wire.
I've seen a similar problem that was a bad coil pack harness.
Dale
I've seen a similar problem that was a bad coil pack harness.
Dale
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that harness no longer exists on my car .. when i rewired the signal wires from coils to igniter .. and from batery to coils ... that harness became obsolete ....
i did the rewiring job because i suspected a possible problem with the ignition harness
i did the rewiring job because i suspected a possible problem with the ignition harness
#15
RX-7 Bad Ass
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Did you have the old style harness? How much of it did you use?
Also, the factory harness has some shielding to prevent interference. If it's picking up some sort of RF interference and isn't well shielded that could cause problems.
Big dumb one too, make sure you don't have something funny going on like the trailing and leading coil signals swapped or trailing one and two signals swapped. With that many wires it's easy to confuse them in your mind. The proper signals need to go to the right coilpacks.
As well, make sure the plug wires are on right - again, simple stuff, but this is the time to double-check and make sure everything's on there right. Swapped leading and trailing will make the car run VERY weird, for example.
Dale
Also, the factory harness has some shielding to prevent interference. If it's picking up some sort of RF interference and isn't well shielded that could cause problems.
Big dumb one too, make sure you don't have something funny going on like the trailing and leading coil signals swapped or trailing one and two signals swapped. With that many wires it's easy to confuse them in your mind. The proper signals need to go to the right coilpacks.
As well, make sure the plug wires are on right - again, simple stuff, but this is the time to double-check and make sure everything's on there right. Swapped leading and trailing will make the car run VERY weird, for example.
Dale
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dale i appreciate it but if i had some crossed wires my car would not drive normally to 6k rpm ..
and i used shielded wires for the coil signal wires which are rewired from the ignitor plastic connector all the way to the colored coil plastic connector .. similar with power wires as well
the problem is the same as before rewiring
it`s simply an rpm dependent WOT backfire ... aroun 6.5 k ... very very loud
i will try to post a vid .. but it`s hardnow cuz my car is stored and snow outside .. cant really drive it around
and i used shielded wires for the coil signal wires which are rewired from the ignitor plastic connector all the way to the colored coil plastic connector .. similar with power wires as well
the problem is the same as before rewiring
it`s simply an rpm dependent WOT backfire ... aroun 6.5 k ... very very loud
i will try to post a vid .. but it`s hardnow cuz my car is stored and snow outside .. cant really drive it around
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