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What tranny? Posted by Ari [Email]  (#2847) [Profile/Gallery]
(more from Ari) on Wed, 20 Jul 2005 10:24:29
In Reply to: Low gas milage, Aom, Tue, 19 Jul 2005 15:37:08 Members do not see ads below this line. - Help Keep This Site Online - Signup |
You can expect a mileage hit of 2-3 mpg with an automatic tranny. That is for two reasons - first, the autobox chews up some power all by itself, and second, the car is slower. Since it's slower, you put your foot into it more to get acceptable performance, and therefore use more gas.
The N/A engine will usually get slightly less gas mileage than a reasonably driven turbo. That's because the 2.3 is a little underpowered for the car. You tend to thrash it a bit more merging on the highway, etc. The turbo is actually more efficient; as long as you don't wail on it all the time, it'll get better mileage.
It would help with year, model, and transmission type. A 9000S from 1992 will get worse mileage than a base 9000 of the same year. That's because the S had power seats, adding significant weight to the car.
As to leaking something, I think what they're referring to is leak down. The fuel system pressurizes when you start the car; until you get full pressure, it doesn't want to start. When you shut the car off, the pressure leaks down. If it leaks down quickly, the car will be harder to start. But the gas is still there. Adding throttle doesn't help, and can hurt. Fuel Injected cars want to be started with your foot off the gas - opening the throttle just means that the computer has to add more gas to make the mixture right. If your starting fuel pressure is low, you've made the problem worse. And with full throttle, the ECU turns fuel off - it'll never start.
With my base '92 9000 automatic, I get just over 20 mpg in mixed driving. On a long highway trip, I can hit 27 or 28 mpg. That's measured by miles on the odometer vs. gas put into the tank. I've never believed the mileage gauge on the EDU in any of my 9K's. That's pretty much the same since new. The car is in very good shape.
All it takes is some very small changes to impact mileage a few mpg. If you got 22 city/27 highway, would you feel better? That's only 10% better. A car can easily pass emissions but not be running at top efficiency. A tired O2 sensor can cause poor mileage. Depending on the year, a weak Air Mass Meter (AMM ) will cause poor mileage, especially in conjunction with a tired O2 sensor. The sensors don't have to be bad - just a little weak, enought to throw the mixture off a little.
Have you checked the front end alignment? Poor alignment in a FWD car can easily reduce fuel economy by 10%.
posted by 192.249....
, Wed, 20 Jul 2005 10:24:29 <-- Viewing This Message
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