gfredrick

I'm only getting about 12 to 15 mpg with my ' 84 944. I'm driving it very gently trying to get the best mileage possible. I'm using 91 oct. fuel. Is this normal? What kind of fuel mileage is everyone else getting???

swimmingly

There's a lot on the boards regarding fuel mileage. From what I hear, a N/A will be fine with the lower octane at the pump.

As for your fuel problems, the best way to diagnose is by getting a smog check. Common things to check are the normal maintenance stuff (plugs, air filter, etc) and O2 sensor. You can probably do a visual inspection of most of those and replace the O2 sensor, which isn't too difficult to do, especially on a N/A.

Legoland951

90 percent of the time is the air flow meter setting (the big dial under the plastic cover, not the allen idle mixture screw). That adjustment made one of my cars from a gross polluter to passing with flying colors along with double the gas mileage to 25.

Keithr726

+1 on O2 sensor. That was causing the bad mileage on my old car.

Tom M'Guinn

You should get much better than 12 -15 mpg. Make sure the basics are good -- air filter, plugs, wires, cap, rotor, compression, and then check the sensors as suggested above, O2, AFM, engine temp, etc.

Crunky

Ok, i tried doing a search on this, but I found no results. What does turning the dial each way do?

Legoland951

Adjusts your main air/fuel mixture. O2 is way overrated as I drove a 944 with the O2 disconnected and still got 25 mpg. O2 will do minor adjustments to your a/f but the main adjustment is the AFM spring tension which controls how easily or difficult the AFM flap opens/closes to tell the computer how much air is coming into the engine.

Zero10

Don't mess with the AFM unless you absolutely have to, and you have the proper equipment to do so (a CO meter).
Change your O2 sensor, most likely it has quit on you.
Then check your fuel pressure, and check for vacuum leaks.

12-15mpg is pretty low, that is what my 951 gets with a heavy right foot, and it has some issues.

Tom M'Guinn

Depends on how it goes bad. If they produce a lean signal, the DME will constantly be trying to add fuel -- making the car run pig rich and waste gas.

DarylJ

Let's say I know of a certian fire truck that has a portable CO meter on it. Let's also say I have keys to said truck and station. Exactly what would my procedure be for verifying if I'm OK or not, and for adjusting the AFM (and what should I do first other than replacing the O2 sensor, plugs, etc first)?

My exhaust stinks. It won't pass a PA emission test....I'm riding on my waiver for this year, and would really prefer to have it pass next year.

Legoland951

I have a smog machine (without the dyno and yeah I know, I am crazy enough to have one at my house not too far from the forklift) in my garage and I don't need it (I do it by ear) to tune for it to pass smog here in CA. Take it to a smog station or someone who really knows what they are doing and have adjusted many of these things for 80s BMW or Porsche.

DarylJ

What fun is that?