Mk. IV Ford Fiesta 1.8 Diesel - nufiesta
Just bought a Mk. IV Ford Fiesta 1.8 Diesel and have noticed a problem - Upon acceleration, the engine sometimes hesitates (a flat spot), and smoke pours out of the exhaust. After a few seconds, the smoke stops and the car accelerates away fine. This happens quite a lot, but not every time I accelerate. I suspect it may have something to do with the injectors, but I'm not too sure about diesels. Can anyone who has had the same problem advise? The car is fine apart from this minor flaw - 1.8 engine is nippy enough, and the car is quiet, but it has done 90,000 miles. Anyone any ideas what might be causing this? Thanks.
Mk. IV Ford Fiesta 1.8 Diesel - IanT
My guess ... Low compression in one or more cylinders.

Diesel fuel is ignited by the heat generated by the compression in the cylinder, so if the compression isn't high enough the fuel may not ignite - causing smoke and loss of power.

On the other hand, I can't see why this should be more likely to occur when accelerating. So maybe there's another explanation.

Ian
Mk. IV Ford Fiesta 1.8 Diesel - BrianW
IIRC, and if not the techies will soon correct me:

White smoke = vaporised but unburnt fuel.(e.g. low compression or air leak in fuel supply)
Black smoke = incompletely combusted fuel.(e.g. overfueling or worn injectors)
Blue smoke = burning oil.(e.g. piston rings, blocked breather or leaking valve oil seals)


Brian
Still learning (I hope)
Mk. IV Ford Fiesta 1.8 Diesel - IanT
On reflection, my second guess is that a fault with the injectors is more likely. Partial combustion will occur if the spray ejected by the injectors is not finely or evenly distributed into the cylinder. When accelerating, the extra fuel could disrupt the spray pattern for a faulty injector, causing the flat spot and the smoke.

Brian's colour analysis looks good to me and should help pinpoint the fault.

Ian

Mk. IV Ford Fiesta 1.8 Diesel - Shigg
Could be worth draining the tank and re-filling with 'new' fuel. My brother bought a Maestro that started and ticked over but wouldn't rev. He rigged up a supply pipe from the lift pump to a can of fresh diesel, worked like a charm. Drained tank and filled up with fresh, he's been running the car about 14 months now. I'm sure some people think you can put any foul smelling fuel into a diesel and it'll work. I think the Maestro probably had some paraffin in the tank.

Steve.
Mk. IV Ford Fiesta 1.8 Diesel - jc
Does your vehicle have EGR?-if so,try blanking off the vacuum pipe to the valve and see what happens.
Mk. IV Ford Fiesta 1.8 Diesel - BrianW
"think the Maestro probably had some paraffin in the tank"

This gives light blue smoke and a distinctive acrid smell.
Brian
Still learning (I hope)
Mk. IV Ford Fiesta 1.8 Diesel - Shigg
Thanks for info, didn't know that! Who knows what was in the tank then.

Steve.

 

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