Fuel Smoke???

[Paul Cochrane]

Gday, Have had my 3.0 csi for around 2 months and am slowly working through the car to understand it. I have found that while I am have had it the only amount of driving I am done is small city km's ie, 10-15k trip at low revs. When I then decided to take it on a longer drive I have found that at around 4500 rpm I have blown some light grey to dark grey smoke. This then clears after around two or three stinits at this revs level (on the same trip), So my question is, is this normal, because in my own simple logic, I see the fuel injection system running a little too rich around town and higher revs is clearing out the waste..(forgive me if that is a silly comment),,Do I need to burn hotter spark plugs or do I just accept it as norm and move onto to other issues?
Would appreciate any reponse.

 

[Malc]

Paul,
no question is silly!
Yes it's quite possible that lots of town driving means the plugs could be sooting up a little, and a good blast will "clear" the exhaust system. You could go hotter plugs but going for a good blast on a regular basis is more fun!

Check that the injection is giving the correct CO at idle and that your timing is good.
You might find that the injection could benefit from a dose of injector cleaner as well.
malc

 

[lloyd]

Sooty exhaust

Your question is a little vague. I'm no expert and I do not wish to be condecending, but what plugs are you currently running? Maybe they are too cold. (IF memory served me correctly Bosch W8DC - W7DC is the norm). Maybe your timing is also a little retarded. Failing those possiblities, fuel injection is the next suspect.

If you use the search feature, there are several sites with a diagnostic check list for the Bosch DJet system.

Remember, your CSI is not getting any younger and unless someone has retrofitted new fuel injection components, there are any number of components that will naturally fall out of calibration (e.g, the manifold pressure sen (found on top of brake booster on LHD models); or the fuel pressure regulator, or the fuel injection points, sensors, or even the brain under the right rear seat.

Needless to say, I would try to eliminate ignition issues first, but if I had to take a wild guess, I'd take a look at the fuel pressure regulator. SO far as I recall, they are adjustable, and if you are running on the high end of the scale (more than 30psi) your car may exhibit symptoms as you describe. Lastly, there is a potentiometer knob on the base of the aforementioned brain that can be used to adjust idle mixture. Just another possibility.