Misfire problem classic
#1
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Misfire problem classic
first of all my car is a 1996 jdm wrx saloon
jus fitted..
Walbro 255
Front Mount
EL headers
550cc injectors
NGK PFR 7B plugs
new coil packs
and had it mapped by duncan @ racedynamix, simtek
when under load it develops a misfire which bogs it down, around 6k mark,
any ideas? all the coil packs are new + plenty of fuel getting in
jus fitted..
Walbro 255
Front Mount
EL headers
550cc injectors
NGK PFR 7B plugs
new coil packs
and had it mapped by duncan @ racedynamix, simtek
when under load it develops a misfire which bogs it down, around 6k mark,
any ideas? all the coil packs are new + plenty of fuel getting in
Last edited by mastarasta47; 12 July 2011 at 11:46 PM.
#7
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As Harvey said, what did Duncan say?
Does it rev freely in neutral?
- also, under load when not up to full operating temperature?
Try checking for high resistance in wiring to plugs when engine is hot.
Does it rev freely in neutral?
- also, under load when not up to full operating temperature?
Try checking for high resistance in wiring to plugs when engine is hot.
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#9
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I replaced 3 coilpacks for better condition used items (3 completely fell apart) when doing the initial mapping and cleaned the plugs up as best I could but the misfire still persists (although less than prior) - it ideally needs 4 new coilpacks and pfr7b gapped plugs to rule that out (whether permanent additions or borrowed). Potential for fuel pump weakening causing it but mixture was bang on the money so unlikely and fuel tables logical. It is a process of elimantion really. Getting a clean spark would be a good starting point IMO.
#11
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ok, gapped the plugs at 0.6 and changed the crank sensor still no joy :|, whats next? getting pretty fed up, considering giving it to a garage to sort out!
#12
Hi,
I had something very similar on my MY99 recently, car missing and detting after 6k rpm on a rr session. Turned out to be my Crank Position Sensor - it was miss-reading over 6k rpm, showing as high as 11k rpm at one point! This of course triggered the ECU to kick the rev limiter in, which induces a rather severe miss-fire!
Changed the sensor and the car revved cleanly to the red line and all traces of det were gone.
I do still have an issue with the turbo not holding the full level of boost it should at higher rpm, but other than that it's going well.
Sensor was £170 FYI...that hurt!
Best of luck.
Cheers,
G.
I had something very similar on my MY99 recently, car missing and detting after 6k rpm on a rr session. Turned out to be my Crank Position Sensor - it was miss-reading over 6k rpm, showing as high as 11k rpm at one point! This of course triggered the ECU to kick the rev limiter in, which induces a rather severe miss-fire!
Changed the sensor and the car revved cleanly to the red line and all traces of det were gone.
I do still have an issue with the turbo not holding the full level of boost it should at higher rpm, but other than that it's going well.
Sensor was £170 FYI...that hurt!
Best of luck.
Cheers,
G.
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#16
Engine Specialist
I'll put a lot of money on it still being a coil pack problem. They should either be replaced with genuine new ones, or replaced with newage ones really.
Graham
Graham
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