Engine very lumpy

2006 Ford Focus 1.8 tdci
Car: Ford Focus
Year: 2006
Variant: 1.8 tdci
Categories: Running Rough, Starting & Power Loss
I have the strangest problem that even a top engineer/mechanic was baffled!

Engine runs sweet as a nut until it reaches optimum temp and then the problem starts
e.g stop the car,put it into neutral, and as soon as you the lift the clutch up it sounds and feels like there is a big missfire happening, the weird thing is that all you have to do to stop this 'misfire' is simply push the clutch back down and engine runs sweet again

No mil lights have come on but just once ive had the powertrain light on (cog with exclamation mark) but that disappears when turning of engine

Ive had clutch and flywheel replaced and that did not solve it

Other problem that about once a week it doesn't want to start so not sure if connected

Would love to hear your suggestions on this its bugging me and i want to get it fixed

Cheers Lawrence
Problem added: Sep 7, 2015 (8 years ago)
Given your description the first thing I'd would be the crankshaft end float.
which basically means how much the crankshaft pully can be moved out from the engine when it's first pushed fully in.
There's always "Some" thrust movement but shouldnt be too much
simple test.
and the only cause I can think of is worn thrust bearings.
Now I can't give you any number as you've neglected to say just what engine/fuel type is in your can.
Answered Sep 7, 2015 (8 years ago)
Further thinking reminds me the crank angle sensor is mounted very close to the gearbox,
So I'm left with a couple of possibles,
my original one about crank float,
you pressing the clutch will move the crankshaft with worn thrusts "into" engine so altering the air gap between the CAS and the trigger which could result in poor/lost CAS signal.
My other is a fault in the wiring,
specifically the wiring from/to the clutch switch.
Either way an oscilloscope connected to the crank angle pins on the ECU and the waveform checked as the clutch is applied ought to narrow it down
Answered Sep 8, 2015 (8 years ago)

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