Hello all and good new year,

I just got an 84 242 turbo, after having

the manifold reattached to the aluminum head I can

address other issues, chief among them is the horrible

mileage I'm getting, I ate up half a tank and only went

a little less than sixty miles. Can you believe it?

The exhaust smells gassy. The performance is great as I've

never had a turbo before it is impressive. Many things have been

taken care of by the PO: new timing belt, recent rebuild on turbo

as well as new oxygen sensor. As the car seems to

eat fuses I plan to clean all the grounds until my new wiring harness arrives. I'm not sure how old the oxygen

sensor is and wonder if it could be involved in the poor mileage.

The idle is high going between 1500 and 2000. I'm not sure

what the right idle speed is for the turbo 900? I'm wondering

if I can adjust the mixture myself though I don't know where the

adjustment nut is. The Idle is chuggy if you will though not

grossly so. The car performs very well I just can't go too far

without the needle going down.

Hi Josh,

If I was in your shoes I would make sure the car has had a complete tune up for starters. I agree it sounds like a mixture problem, I'd take in into a Volvo specialist and have them set the A/F ratio to stock and check the ignition timing... I've had it done to mine, since I don't have one of those nifty machines that have a sensor that goes up the exhaust pipe and checks the emissions of the car, turned out both the A/F and ignition timing were off quite a bit.

Best of luck,

Will

I replaced my oxygen sensor after positively identifying it as bad. The much described voltage test is absolutely valid and easy. Use a high impedence multimeter though - translation, usually relatively expensive and/or digital. My gas performance improved, as did my emissions. However, my mileage was significantly better than yours to begin with, so I suspect there are other things involved instead of, or in addition to this.

I wouldn't be surprised if your cat is trashed as a result of high levels of hydrocarbons, but that won't influence gas mileage; just something else to ponder.

I can't say much about adjusting the mixture, not having done it myself. However, I have seen many people discuss the fact you can do this on many 240's relatively easily. I think you can't do it starting in very late 80's early 90's but I don't know the specific model year this changed. Search brickboard and I'm sure you'll find information.

Another thing many people mention is the circuit that returns fuel to the tank. If that is impeded in some way, you will end up with too much fuel going into the cylinders. This is a gross simplification of the problem, but I mention it because it might lead you in another direction you didn't discuss in your original post. Again, I have not had to deal with it with my Volvo, but I have seen it come up on Brickboard from time to time. Just another avenue to pursue.

Good luck. Volvo's are great cars.