Misfire on rear rotor

[Dazza44]

Good morning all,

As above i have a misfire on rear rotor,this only ever happens now and again and the only time this happens is when the car is cold and not been used for a few days,it only does it on start up(so car idles rough),this last for no more than one minute then car runs sweet. As said only ever does this when car hasn't been used for a while.
Any ideas?
Mazda rev c coils 10k in
Magnecor leads 10k
Sparks about 10k
I be checked leads on plugs properly
Check coil connections
Plugs look pretty good(light brownish colour.
Thanks for any help/advice
Dazza

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[BigPete]

It could be the Eccentric Shaft Sensor playing up.

One of the failure modes does kick-in when the sensor is cold and been left for a while.

Sometimes it only triggers the flash CEL and misfire code, while not actually making the engine any more lumpy than usual from cold.

The only way to tell would be substitution with a known good one, used original not a dodgy aftermarket replacement.

My suggestion would be to just keep an eye on it and try a swap, if it gets worse.

Mine threw a wobbly a couple of years ago and a replacement from Bigpete did the trick - even though I only got as far as leaving the replacement in the centre console. ...



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[Dazza44]

Thanks very much Dave I haven't check the connection on the ess I take alook at that just to rule it out as well,and if it persists I look into a replacement.

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[350matt]

Before replacing the ESS sensor clean it 1st as its very prone to collecting debris and then do the 20 brake pedal stomp to reset it