My 82' 245 automatic is only getting 18 MPG.
I'm driving it over 100 miles per day and gas $$ is killing me!
Anyone have any ideas as to how to increase gas milage?
Thanks

That's what I have too, with automatic trans 3speed OD. I get about 24mpg on regular fuel. It only took me about 5 years to get things really going right. Here are some things to take a look at:

1. Replace the engine electrical cable harness if still original. The original cable insulation would crack, and fall apart, the connectors were not very good either. Some symptomes: , bad idling, rough idling when costing the car lurches, car won't start, hard to start when it should, or if you ever disconnected the cable harness from the computer in the engine compartment. Buy a replacement cable harness. Dave Barton carries these used: http://personal.linkline.com/dbarton/WireHarnesses.html

Instantly all of my rough engine idling problems went away.

2. On a full tank, you get strong fuel vapor smell. Less as the fuel level goes down. Maybe high idling speed to about 2500rpm when hot. Maybe fluctuating idling when hot. Hard starting when hot after driving and sitting for a while, like it's flooded. For me that was the water temperature sensor gone bad. Cost about $30. That's in the 700/900 FAQ. Pays for itself in 4 tanks of gas.

3. Vacuum leaks abound with cracked and broken rubber hoses. Buy about 6' each of various rubber tubing and replace all the stuff including the vacuum tubing leading to the heater controls.

4. Broken one way vacuum valve to the heater control. If your heater control does strange (sighing sounds) things depending on how you accelerate or idle, then the valve needs replacing which causes some small economy problems overall.

5. Get your overdrive solenoid replaced if broken. This is easy to replace if it's burned out, get the two o-rings too. Expensive as parts though, but you need it.

Items 1, 2, 3, 5 are the major items I think you can check and replace as needed. I'm pretty sure you will need to do a #1, and 3.

Hint: This was mentioned once before. On accelerating with an automatic, you want to get to the overdrive gear as fast as possible without flooring the car and wasting fuel. Unlike a manual shifter, to get best economy, the 240 needs to get to OD right quick.

Clean throtle body ...tune up ...check tire pressure...go by what is on the tire not on the door jamb...a lot of the new tires are designed to roll easier but recomend 45 psi instead of 32 to 35...just saw a bit on tv about these...I actually have 2 sets that take 45 psi but did not know why unill I saw the bit on tv...they say improper inflation can cost you as much as 10% fuel milage.
--
rust free in west Texas

For gas mileage, it's kind of amazing that such heavy tanks can get in the high 20s and even up to the low 30s (reported on this site by people who have M47 5-speed manuals; I've never been north of 27 or so with my auto tranny 240s). This impressive feat of Swedish engineering also means that they are really sensitive to things being just a little out of whack. 240s really respond to taking care of all the basics:

• Make sure it is completely tuned up and maintained (check especially AMM, Oxy sensor, plugs/wires, air filter, throttle body cleaned, no intake or vacuum leaks).

• Regular check your tire inflation. Go a little higher than the Volvo recommendations printed on the label in the door jamb but don't exceed the maximums stamped on the tires - proper tire inflation easily could make 3-4 mpg difference alone.

• Don't carry unnecessary loads.

• Don't use the A/C (if it works at all - if you have an earlier model consider doing the A/C condenser bypass from IPD).

• Don't drive with the windows open. Of course this advice obviously conflicts with the last item in the summer. If it's gotta be one or the other, open windows are much less of a drag on mpg than the A/C.

• Go light on the pedal and don't speed. The difference between 60MPH and 80MPH will cost you 3-5 mpg. Don't even kid yourself about trying to push the acceleration in these machines. Follow the sage advice of my father for maximum mpg and vehice longevity: drive like you have an egg between your foot and the pedals that you're trying not to break.

Actually, fuel injected engines getter better efficiency by hard stomping the gas to get up to speed. An engine gets the best economy at wide open throttle. The pedal and egg thing is a holdover from the carberator days when you had an accelerator pump that injected more fuel if you whammed the pedal down.

True fact: Studies have shown better economy by getting quickly up to speed.

Your answer oversimplifies - you want the engine to operate at its point of lowest bsfc (brake specific fuel consumption), which as you say generally occurs at wide open throttle (to eliminate losses from throttling), but at somewhat low engine speeds. In other words, while you want to get up to speed at wide open throttle for best efficiency, you also need to shift at low engine speeds rather than revving the engine up in each gear. European taxi drivers with stick shifts drive like that (pedal to the floor and short shifting).

Zack
1980 245DL M46 275k
1985 744TD M46 251k
1988 745T+ M46 203k

The high load is important to the efficiency of the engine. Thats why the newer hybrid vehicles have the recharge load the engine during driving. People don't like to hear engines heavily loaded, but they are at their most efficient then. I was part of a team that built a hybrid SUV that used hydrogen gas as the fuel. Sadly, its still way-off in the future.

i have read the with the drag on the vehicle at 45 mph you might as well run the air cond. good luck

My two data points:

1. 1980 wagon, K-jet, York compressor: Minus one mile per gallon, city and 1.5 miles per gallon highway, when running the AC full-time.

2. 1992 wagon, LH 2.4, Kiki rotary compressor: Can't tell any difference, city or highway. I spoze there has to be SOME difference--but if I burn a full tank on the Interstate during a long trip, winter or summer the fuel consumption comes out the same.

Of course, your mileage may differ.

Doug Harvey

get the timing and point done, and quit trying to go fast; it's a slow car, and if you accept this it will get better mileage. Best economy is at 55mph. Sorry dude.

I get much better mileage on premium (94 octane) but I have a carburetor.

Keep tire pressure at 35.
--
Stef -- 1981 245 B21A SU M46 323000km my volvo pages

tune up, new spark plugs, wires. check you oxygen sensor and the air mass meter. a bottle of fuel treatment could help. perhaps a new air filter.

good luck!
ross