Disco 2 - despair

I have a 1999 DISCO 2 auto and it has developed a dam annoying
problem. Initially it started out that if i drove above 2.5k revs it
would start to miss fire and if pushed too hard i would loose all
power at the throttle and the engine warning light would appear, a
restart was required to clear this. I was informed it was likley to be
oil in the ECU, a common problem apparently. So i have replaced the
injector harness and the engine wiring loom, decontaminated the ECU
circuitry. Replaced the fuel and air filters in case it was some thing
so simple...! But to no avail. The problem is now becoming so accute
that the engine misses when ever the slightest load is placed on the
throttle. I have recently found out that i can accelerate on the
cruise control to above 4k revs with out any miss firing. Any one got
any ideas please?

Yes its overboosting so the ECU is cutting fuelling to prevent engine damage.Check the small rubber hoses on the boost control modulator first then check that the wastegate arm on the turbo is not seized - it must be free to the point of being sloppy.

Hi,

If as you say its will not rev/pull using the accelerator pedal, but does when using the cruise control then problem not the turbo.
More likely electric.
Disco's have drive by wire system, as you press accelerator electrical signal sent to engine, similarly when you use cruise control.
So I think problem with accelerator potentiometer !

Hi,

dont know if this might help,is it a petrol model with a mass air flow meter
fitted.I had same probs on a previous car,a petrol engined merc.It would missfire when trying to accelerate,also had loss of power & was sometimes lumpy at idle as if missing a cylinder. I replaced the MAF sensor (usually fitted after the air filter & before throttle housing) & it cured the prob.

Please ignore this post if yours is a deisel (i dont think they have a MAF),

Best of luck,

Kertir.