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Discussion Starter · #1 ·
The lads car Engine management light comes when sat idling, the fault code p0303 - miss fire on cylinder 3 - so we did the coil pack check no difference on 3 when removed so cleared the fault, purchased a full set of coil packs & new plugs, fitted them car ran great for 10 -15 mins, then missing again same code, really scanned it got new fault codes p0303 again & the Map & Mfi sensor code, so purchased new map sensor, same again ran great - 10 - 15 mins later P0303 code, so was told could be the camshaft sensor, so pulled the sensor can cough and started running awesome, so ok another sensor replaced both sensors and you quessed it 20 mins in engine management light on p0303 error car miss firing on 3...... if you clear the fault and drive the car it's great no miss fire drives awesome soon as you stop and idle the light comes on ..so big question any ideas because I've ran out now lol
 

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would do a compression test see what you have, have seen a lot of cracked valves where once engine revs it sort of feels ok ish then under no load the crack dumps compression,, also injectors have a habit of going screwy or dirty,, i use seafaom and also add injection cleaner to 1/4 tank of fuel and drive it hard for a while also leave to soak as well help after,
seafoam
also seafoam can be added to oil 50 miles before change oil cleans out ie melts the carbon
also worth removing injector rail and flip it upwards and crank engine over can see them is any injectors are not atomising the fuel correctly.
 
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if any corroded connections you would get a fault code flagged, if no fault codes other than misfire based codes then mechanical or injector issue, just in middle of doing a cooper s engine that had miss on 4 smoking really badly turned out broken piston caused by the timing chain stretched and kept driving it hard then blocked the cat up,, ended badly now all pistons out found all oil rings cracked and broken that compression tested at nothing on number 4 and the others were 120psi,, the oil use blocked off the cat and caused back pressure and heat spike back to cylinder 4 and blown the bottom part of piston off
 

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Discussion Starter · #7 ·
Thanks Guys, i brought a new compression tester they are coming out at 175 psi on all four cylinders so I've took it to a garage and had it plugged into a super computer and we have narrowed it down to bad wiring loom on three or Ecu, so I need to chase the wiring back and check it out. Failing that have the Ecu tested.
 

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Discussion Starter · #8 ·
if any corroded connections you would get a fault code flagged, if no fault codes other than misfire based codes then mechanical or injector issue, just in middle of doing a cooper s engine that had miss on 4 smoking really badly turned out broken piston caused by the timing chain stretched and kept driving it hard then blocked the cat up,, ended badly now all pistons out found all oil rings cracked and broken that compression tested at nothing on number 4 and the others were 120psi,, the oil use blocked off the cat and caused back pressure and heat spike back to cylinder 4 and blown the bottom part of piston off
That look fun lol
 

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That look fun lol
was joking with a guy the other day he stuck his nose in to have a look at all in bits he laughed that looks like a nightmare to put back together,,, made me realise i know where all the nuts and bots etc went back to and what order like a second nature i've done so many now, must admit i still like that feeling when first start them after a big pull down, like this one was a smoke cloud knocking and missing etc, end of week it will be like a new one again,, also going to decat it and add a rolling road run on it so should be 230bhp ish safe power when done, mapped for low down grunt more than top end revs is best way with them gives the mid range more tug
 
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