 Efi misfire
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Joined: Jun 2010
Posts: 1,193 Likes: 22
Learned Hand
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OP
Learned Hand
Joined: Jun 2010
Posts: 1,193 Likes: 22 |
Well, theories invited. My 014 LT has developed a slight misfire....only when hot after about 25 miles on the road and on a steady throttle only....revving it is fine...occasional backfire too.
My first option is a failing ignition coil....or plug or HT leads....but being efi it gets complicated.
Could be any of the sensors, perhaps crank position sensor or a leak in the map hoses.
Or possibly a tight exhaust valve.
Any more options to keep me from boredom?
Tempted to buy new coils but at £100 each?
Bah!
I took the Road Less Travelled.
Now where the ****** am I?
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Re: Efi misfire
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Joined: Jan 2005
Posts: 1,204
Learned Hand
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Learned Hand
Joined: Jan 2005
Posts: 1,204 |
Check your coils, air leak or HT leads. It won't be crank sensor. That leads to no start conditions. If you haven't adjusted the valves most recently then it can't be a tight exhaust valve. Your valves loosen over time with mileage.
1200CC BIG BORE, W/WISECO PISTONS,.250 STROKED CRANK, PORTED/POLISHED HEADS AND LARGER VALVES, CUSTOM WELDED EXHUAST, DUAL 42MM MIKUNI CARBS.
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Re: Efi misfire
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Joined: Jun 2010
Posts: 1,193 Likes: 22
Learned Hand
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OP
Learned Hand
Joined: Jun 2010
Posts: 1,193 Likes: 22 |
Thanks...that's helpful.Valves done 2.5 k miles ago for the 12 k service......so I guess that's unlikely.
It may take me a while to sort this one out...I'm off to Cyprus on Sunday for a week or so...
I'll start working through the options on return.
I took the Road Less Travelled.
Now where the ****** am I?
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Re: Efi misfire
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Joined: Jan 2008
Posts: 1,174 Likes: 15
Learned Hand
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Learned Hand
Joined: Jan 2008
Posts: 1,174 Likes: 15 |
have you looked at the error codes? they are found on the diagnostics page of tuneECU. anything that happens that should not would be listed, but not necessarily show a 'check engine' light on the speedo.
you can test with the engine running
05 speedmaster - 1100cc, 11:1 racing pistons, Carillo rods, thunderbike cams, ported and polished head, 2mm over intake and exhaust valves, Barnett kevlar clutch, scepter pipes, oversize manifolds, 45mm HSR's, TTP stage 4 firestarter
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Re: Efi misfire
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Joined: Jun 2010
Posts: 1,193 Likes: 22
Learned Hand
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OP
Learned Hand
Joined: Jun 2010
Posts: 1,193 Likes: 22 |
I'm not that tech savvy.....I'll probably run it up to my dealer if I get stuck....they can plug it in and tell me what's showing.....current prime suspect is map sensor.
Given its fine when revved and stutters when hot on low throttle openings, that might fit with map sensor issue.
I took the Road Less Travelled.
Now where the ****** am I?
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Re: Efi misfire
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Joined: Jan 2008
Posts: 1,174 Likes: 15
Learned Hand
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Learned Hand
Joined: Jan 2008
Posts: 1,174 Likes: 15 |
have you checked the MAP hoses? there are 2 of them and the ridged line parts come out of the rubber hose end parts pretty easily. also the rubber bits can crack with age/heat.
you said you were bored, good time to get more tech savvy!
Last edited by mag10; 09/25/2017 12:30 PM.
05 speedmaster - 1100cc, 11:1 racing pistons, Carillo rods, thunderbike cams, ported and polished head, 2mm over intake and exhaust valves, Barnett kevlar clutch, scepter pipes, oversize manifolds, 45mm HSR's, TTP stage 4 firestarter
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Re: Efi misfire
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Joined: Jun 2010
Posts: 1,193 Likes: 22
Learned Hand
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OP
Learned Hand
Joined: Jun 2010
Posts: 1,193 Likes: 22 |
Thanks...I'm in Cyprus this week....Will take a look when I get home.
I took the Road Less Travelled.
Now where the ****** am I?
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Re: Efi misfire
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Joined: Feb 2007
Posts: 23,237 Likes: 63
Fe Butt
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Fe Butt
Joined: Feb 2007
Posts: 23,237 Likes: 63 |
Quote:
Check your coils, air leak or HT leads. It won't be crank sensor. That leads to no start conditions. If you haven't adjusted the valves most recently then it can't be a tight exhaust valve. Your valves loosen over time with mileage.
Usually, unless the valve has burned or seat is erroding. That is just for info, valve is not likely so soon.
I learned all I need to know about life by killing smart people and eating their brains.
Eat right ,Exercise ,Stay fit, Die Anyway!
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Re: Efi misfire
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Joined: Jun 2010
Posts: 1,193 Likes: 22
Learned Hand
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OP
Learned Hand
Joined: Jun 2010
Posts: 1,193 Likes: 22 |
Okydoky
Will work through the options starting next week.
I took the Road Less Travelled.
Now where the ****** am I?
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