bad ignition timing -> low mpg
 

Hi Folks,

during the last year my mpg constantly drops. Lately I replaced the fuel filter without any result. Can a slightly wrong ignition timing lead to higher fuel consumption? Or what else do you suggest.

Harry

Worse-case scenario for bad engine timing is lack of power or detonation. Maybe your driving style has constantly changed within the last year? At any rate, your engine's timing has a small effect on economy; the difference between running retarded (timing) and running way to advanced is usually no more than .5-3mpg. Keep in mind that temperatures effect fuel ratio quite a bit, as does load and drag.

A 3 mpg change when you only get 18 or so to begin with is pretty significant.

Yes timing can effect gas mileage. There are many things that can. Just start checking/adjusting everything until you narrow it down.

Thats right! I used to have about 25 mpg and now its about 21, without changing my driving style and still drive the same road to work every day.

I thought it might be timing because it sometimes backfires after high rpm and suddenly decellerating. My car never did this the years before.

Thanks anyway!

Harry

look at your spark plugs. may be wearing out.

UPDATE
 

Visited my mechanic today:
Ignition timing is pretty good.
But the car seems to run too rich because the Co2-Values are to high (should be 0.1% but is 0.7% btw. europe-model without cat) but they didnt want to change the mixture :-(
I know the idle mixture screw is near the air-box. But there seems just to be a round screw in there that you cant turn!? Any help would be apreciated.

Harry