[mike1967]

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,

350ml BOTTLE OF TECHRON CONCENTRATE PLUS GASOLINE / PETROL FUEL SYSTEM CLEANER | eBay

ALL ARE NEW. AT WORST BOTTLES DUSTY.

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seafoam

2X SEA FOAM Diesel Petrol Engine Injector Cleaner & Fuel Stabiliser SeaFoam SF16 18812000019 | eBay

For Carburettors or Fuel Injected Gasoline Engines – Autos – Trucks – Tractors – Motorcycles – Marine – Small Engines – Industrial Engines Great for Diesel Engines Too!

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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.

 

[mike1967]

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

 

[mike1967]

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