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Cosworth just backfiring on ignition

Old 16-05-2015, 03:55 PM
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BRAMMER
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Default Cosworth just backfiring on ignition

The car won't fire it keeps back firing - i did have this running about a month ago but recently just give up

new cps 0.8mm, phase 0.25mm, new plugs, leads & tried replacement coil and nothing - it has a spark and a good one but won't fire.
The only thing is the fuel was 18 months old and i topped it up with a gallon of fresh is it likely the fuel is bad or should i be looking in another area?

Timing appear fine as the engine was just rebuilt and everything lines up as it should?
Old 16-05-2015, 04:03 PM
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Mark Shead
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First check plugs not wet if ok change leads around as sounds like firing order wrong.

Mark
Old 16-05-2015, 04:07 PM
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Thats what i thought but why as the coil is numbered and the specific lead goes to cylinder as wasted spark

With all the timing marks lined up all appear to be in the correct position - the dizzy hasn't the arm and the notch in the shaft is facing the mark on the body around 1 / 2 O'clock - but the pickup on the shaft doesn't meet the phase. Should it when all others line up?
Old 16-05-2015, 04:15 PM
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Originally Posted by BRAMMER
Thats what i thought but why as the coil is numbered and the specific lead goes to cylinder as wasted spark

With all the timing marks lined up all appear to be in the correct position - the dizzy hasn't the arm and the notch in the shaft is facing the mark on the body around 1 / 2 O'clock - but the pickup on the shaft doesn't meet the phase. Should it when all others line up?
Don't worry about marks swap them over and try.

Mark
Old 16-05-2015, 04:16 PM
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It's a quick 1 min check to see what it changes.

Mark
Old 16-05-2015, 04:57 PM
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What formation mark swap 1&4 on the same bank or swap them with 2&3 ?
Old 16-05-2015, 05:05 PM
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Originally Posted by BRAMMER
What formation mark swap 1&4 on the same bank or swap them with 2&3 ?
Swap 1 4 to 2 3.

Mark
Old 16-05-2015, 05:14 PM
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Mark it fire fine and ticks over, if you throttle its a little spluttery - Mark i don't understand pal
Old 16-05-2015, 05:15 PM
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mine done the same when I changed to wasted spark after swapping the leads around it fired up.
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Old 16-05-2015, 05:16 PM
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Originally Posted by BRAMMER
Mark it fire fine and ticks over, if you throttle its a little spluttery - Mark i don't understand pal
probably all the fuel you've pumped into it trying to start it?
Old 16-05-2015, 05:28 PM
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Just check to make sure it's timed correctly and not 360 out.

Mark
Old 16-05-2015, 06:34 PM
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Originally Posted by Mark Shead
Just check to make sure it's timed correctly and not 360 out.

Mark
Cheers Mark info massively appreciated, i'm absolutely confused still but the car runs like a swiss watch with a new set of plugs in it so i'm back on track
Old 16-05-2015, 07:00 PM
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Originally Posted by BRAMMER
Cheers Mark info massively appreciated, i'm absolutely confused still but the car runs like a swiss watch with a new set of plugs in it so i'm back on track
Its one of the most common problems and such a easy out to check,
I had a Mini race car come in doing the same and had been to several traders before and they couldnt find it,
I had it running inside of 5mins.

Mark
Old 17-05-2015, 05:07 PM
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Originally Posted by Mark Shead
Its one of the most common problems and such a easy out to check,
I had a Mini race car come in doing the same and had been to several traders before and they couldnt find it,
I had it running inside of 5mins.

Mark
Crazy, will remember that one
Old 31-05-2015, 07:20 PM
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Glad it's ok bud and well done mark!
Old 31-05-2015, 07:34 PM
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If the coil is working backwards from its labels, either don't worry about it, or swap the blue and purple wires on the wasted spark driver where they solder onto the ecu pins.
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