[Engine 850 2.0 LPT] Mysteriously high fuel consumption

[Norwegian]

Gents,

Just wanted to throw this little problem at you: Low mileage, no apparent reason. I'll be most thankful for any and all suggestions that may shed some light on it.

Engine is a 1996 2.0 Low Pressure Turbo @ 175 PS, with a modest 250 000 km on the clock. Around town I struggle to get more than 17 to 20 mpg even with an egg on the accelerator. On highways, the absolute best I can hope for is about 27 mpg, at constant 100 km/h, but at the end of the day it is more like 23 mpg. Surely, with careful driving I should get more out of it?

Now, the funny thing is that the engine runs absolutely smooth at all revs. No burbling, no hunting, no rough idle, nothing.

I do have a distinct feeling that it runs rich. When starting it always have to turn over at least 5-6 times, when it starts it runs momentarily high (1500 revs), then drops to normal. Starts slightly faster when warm, but not as quickly as most other cars I have owned. Some say this is just the Volvo way - is it really? Smells of petrol, too, when starting. When accelerating it lacks that last oomph that I've felt in other cars with comparable engine size. Smooth, but not entirely willing, if you see what I mean.

Stuff I've done recently (and which have changed absolutely nothing):

FCP tune up, with dizzy cap/rotor/OEM plugs/OEM plug cables/air filter/oil filter/fuel filter/PCV-kit/Lambda sensor/engine oil new. Old PCV wasn't too clogged, but very brittle.

Cam belt, tensioner, roller new.

Rear cam seals, both turbo oil pipe seals (did stop the dripping, though).

Vakuum lines seems to be ok, no apparent leak from induction line either. Drop of oil hanging under the turbo, always, but no apparent blue smoke.


So, what may be the cause(es) of consistently low mileage without rough running? No fault codes stored, by the way.

- Vacuum leaks, after all? And if so - where, most likely?
- Faulty MAF?
- Late valve timing?
- Tired turbo (will refurbish soon anyway)?
- Wrong fuel pressure?