Passat 1.9TDI SMOKING

What color is the smoke? How much smoke is there? When and for how long does it smoke? Where are you (climate)? When did you last change the fuel filter? Is the smoke concurrent to a recent fill-up?

Peter Wieck Wyncote, PA

Hi, the smoke is grey,it smokes any more than 1/4 throttle to full , lots of smoke then it clears. The car pulls well but smokes when accelerating and has a flat spot just under 2000 revs.The car was serviced sept last year about 2100 miles ago.I live in England its cold and wet at the moment.I use the same fuel station every fill up.Thanks for your help.

Well, if you changed the MAF and now it smokes do you have the right MAF ?

Yes the same part number.

Black Smoke is mostly unburnt fuel and/or poor timing. _DARK_ grey smoke is usually contaminated fuel or a very small amount of burning oil mixing with contaminated fuel. When is the last time you drained the water out of your fuel filter? _LIGHT_ grey smoke is usually burning oil to a serious degree. If you are burning a very large amount of oil, the smoke will be a dense, white, stinky mess. Smoking when accelerating could be bad timing as well. _White_ sweet-smelling 'smoke' is usually burning coolant.

Suggestions:

a) make sure that the timing belt is good and within its service interval, and that it has not skipped a notch. b) change your fuel filter if more than 30K miles (45km) old. Drain the water in any case. c) run a can of Techron, or if you can find it Chevron DELO fuel additive through the system. Follow the directions on the container. Fill up with fresh diesel fuel when you do this.

You may also have gotten some high-paraffin diesel (high-wax content), AKA "summer fuel" and/or additive-free heating oil. That stuff _WILL_ smoke although in theory it should do no harm to the engine. What happens is that suppliers sometimes (rarely but it happens) mix up at the yard, especially if tankers do double-duty, delivering heating oil some days and diesel some other days. The sovereign cure for this is to add a few gallons of kerosene (up to 1/3, as it happens) to thin out the diesel. NOT GASOLINE. NEVER gasoline. This also helps with winter starting although your mileage will drop some.

Peter Wieck Wyncote, PA

Thankyou very much for your help, well check the belt and timing first.Cheers, Alan.

I've been told after fitting a new air flow meter i need to reset the ecu, is this true and how do you do this ?