im running stock blacktop set up

today while on the motorway it started misfiring and back firing, with some black smoke,

stopped a few times and it seemed to clear a bit,

on the way home a few hours later i stuck to just under 50 and it ran fine all the way, about 30 miles

took the plugs out and they are sooty black

any help as to what to check first ?

[Edited on 14/5/17 by scottie]

Engine temp sensor, if it's going south or has a dry joint the car will over fuel, also air temp sensor just not to such a great degree.

Hopefully you still have th OBD port so can monitor the values.

[Edited on 14/5/17 by mark chandler]

just running it up to temp just now to plug it in

coolant temp sensor V 0.5
coolant temp 99 degrees

Does the stock ecu have a map sensor? Check for leaks low vacuum will richen the mixture.

Also worth checking the tps, but thats a less likely cause, as tps richens when the throttle is s
'Snapped' open.

My guess is an air leak.

They don't have a map sensor, they run maf instead.

If it's a Blacktop Zetec ecu then you should be able to view Dtc and real time data via the obd2 port.

done a smoke test on the air/vacum side of the inlet and there seems to be no air leaks

could it be anything to do with the O2 sensor ?

sorted, o2 sensor wasnt sired up correctly

took it for a spin and plugs are now spotlessly clean :-0

Live data from the obd2 would have been able to show you A) it not switching and B) a code.


Pleased it's sorted.