Hello all, I'm Black Shuck from Norfolk. I've just bought a Ford Focus TDCI the 115 bhp version. Great car and great pace but has a strange problem. Have noticed when the engine is warm it feels like the engine is juddering as if not enough diesel is getting through causing the car to feel like it's slowing down. It's accompianied by a strange metallic roaring sound and a plume of black smoke. This doesn't happen all the time, yet seems to be becoming more often. Am really worried incase there's something terribly wrong. Not being mechanically minded doesn't help.

 

I posted this under the general tech section as well, but I am reposting in case you missed it ...

From my VERY LIMITED experience with Diesels, black smoke means poor combustion because of too much fuel or too little air. Since yours is turbo, the problem could come from either injection problems (too much fuel being injected at times) or the turbo spinning down (thus cutting the normal air supply) due to mechanical problems.

Your turbine should make a very faint, high-pitched sound if running properly - this should be especially obvious when stepping up on the "gas" pedal. Have you ever heard the turbo squeaking? That would be a sign of running without proper lubrication, which is a sure sign that death is near...

You said you heard a roaring noise ... did that sound like moving parts scratching against fixed parts, or just rumble from the engine?

If you don't already have a turbo boost gauge on the dash, try connecting a pressure gauge to the intake (downstream from the turbo) and keep an eye on the air intake pressure while you drive, especially when you get the problems you described... This may be a good starting point.

Is your OBD system putting out any codes? Do you get any warning lights on the dashboard? Did you try connecting a scanner to the diagnostic port and see what the engine has to say in this matter?

HTH ... let us know what you find. Good luck!