[mike1967]

hmm so the other 3 pistons were fine then i guess, if so would be looking at, 1 injector warn out, 2 exhaust valve leaking,, spark plug failure worth checking to see if tip burnt off common when coil fails or and spark plug worn out, also carbon build up on rear or valve inlet side restricts air then there is not enough air to burn with fuel and washes the crown of the piston,, i tell you this because you could spend all your time thinking its a poor remap from somewhere when the truth is something has failed caused a hot spot,, also at 40.000 miles on a mapped prince engine that has been driven hard will be by now running retarded due to timing chain stretching as they all do the harder they rev the more its wears out. i would not run it again until i knew what was causing it, if all 4 pistons show damage then chain most likely,, also mot time emissions has car seen any mot's since being mapped if so and pass on gas checks then chances are it got a fault not bad calibration

 

[mike1967]

did you do a hpi on the replacement engine as well reason behind this is some breakers have low mileage registration numbers they use for all kinds of engines like for like i know its dodgy as, hpi you can check the engine numbers these cant easily be faked, i work for a mapping company and have never seen a the map as being the faulty part of it all when its melts 1 piston and to be honest anyone that has just spent 100k on all the gear you need to map a car with rollers as well etc just would not make mistakes like that, but what does happen is when car is very new car gets mapped and has it gets old it gets weaker or other faults nothing to do with a map ie file change etc,
i would not reuse your old injectors, or plugs or coil packs i would hope you got those with the 40k engine and was plug and play

 

[mike1967]

honestly i know i bang on about them they really are the one thing on prince engines that must not be ignored if you have a spare £100 just sick a basic kit on it ie due to your engine 40.000 miles in another 20.000 miles you should be doing one anyway so much easier wit engine out,, ie new chain new bolts new oil seal and must do bottom sprocket then just enjoy the car,, like said before the melt down is a 99.9% due to a component failure on that cylinder, trouble is as well most ill informed garages or so called techs who dont know what the hell they are doing always pull the ITS BEEN MAPPED MUST BE THAT, all mapping is is turning up the little bit of power car makers leave in the ecu to meet emissions rules,, did you know that peugeot put same prince n18 engines in their RCZ and run 269bhp factory bhp and they run fine as long as timing chain and good services and some common sense , ie let warm up and let cool down for a start, very easy to blame something that most people dont understand,

 

[mike1967]

there is a bleed screw on thermostat housing, also one on the inlet pipe for heater matrix within under bonnet baulk head, on gen cars if they dont just bleed up buy un screwing these bleed points then chances are one or move coolant pipes are on wrong way around, common is top and bottom rad houses this allows a air pocket at coolant temp sensor tends to throw fan on,