brucec59

I have been tracking my fuel consumption since I got my 993 over 2 years ago. My gas mileage is slowly decreasing. I used to get 15-17 mpg, now I'm getting more in the 14-15mpg range. It's rare that I see over 16mpg on a tank these days.

(BTW, the best mileage I ever got was 22.3 mgp on the superbowl drive a couple of years ago. Seems the car gets better mileage over 90mph than it does around town!)

(Another BTW, I'm not concerned about the fact that my mileage is low, just that it is changing. My driving involves very little freeway, and I drive fairly enthusiastically, so as not to "baby" the engine.)

So, what could be the reason for this? When I got the car, it had 84k miles, now it has 106k. It uses a quart of oil every 900-1000 miles. Is this just normal wear causing mileage to slowly decrease over time?, Are my cats getting clogged (engine revs fine)? What else can I look at? Or should I just not worry about it?

Thanks.

Robin 993DX

You recently changed the brand of tires?

JM993

Some possible causes: leaky fuel injectors, old plugs, dirty air filter.

chris walrod

Dirty MAF -- I recently cleaned the MAF in my xB and immediately found a 2mpg increase. Worth the work to do it.

Edward

Chris,

How'd you go about cleaning the MAF? Details, if you would??

Edward

Robin 993DX

Edward, the Porsche MAF is mounted the same way as on the Ferrari. They are secured by two "security torx-plus" screws, 5 star shape instead of 6 like the normal Torx.

There are special MAF spray cleaner that you buy at auto parts store that's specifically used to clean the MAF sensor. The rest is of course be careful not to touch the hotwire element, etc etc etc.

JasonAndreas

Poor gas mileage is usually the first sign of a failing O2 Sensor.

grouchy

My 95 usually gets around 15mpg for short city runs and then 21mpg for trips around 70 to 150 miles.

Surprised me on a 2000 mile trip from Indiana to Nevada. Hit 25.9mpg, around 80 mph, 91 octane, running up and down mountains and such.

Jack of Hearts

15 is very low. My commute is 20 miles and involves some freeway and some city driving--average is 30 mph according to years of monitoring by the computer in my Volvo. On that run my 90,000 mile 993 gets 18-19 mph, depending how much boot I put in it on the freeway. Even so, I use the Volvo on heavy traffic days when I think I will be forced to idle a lot. These cars were not meant for that.

Mr Swed

Higher ethanol mix in the petrol, due to environmental issues?