Gas Mileage

[wanga]

Hey!

I'm an owner of a 99 TC Exec 455k miles. If I'm lucky I am getting 9.9 MPG city. Is this normal? What can I do to improve gas mileage?

[Bearfoot]

455k ???????????????????????? That's 50,000 miles per year!!!!!!!! 260 miles a day, 5 days a week.

If you've got that many miles on the car it is surprising it's still running......

On my '95 TC I get 22 town and 27/28 open road - that's driving gently as an old man should.

I just filled up my Dodge Diesel...$121.00 At 17 mpg. I only drive it when necessary!

[wanga]

The car was very well maintained :-)
ABE at another forum I post at has been a really big help and offered a few suggestions. I'll post them here for anyone that wants to improve their gas mileage:

Here are some of the things that worsen my fuel economy:

- Short trips where the engine does not reach operating temperature or cold engine is a high percentage of the trip;
- Warming the engine at idle instead of driving away after a couple of seconds;
- Idling the engine for longer than a traffic light stop;
- rapid acceleration from stops;
- not anticipating stops and braking hard for them;
- brakes dragging due to lack of maintenance;
- carrying excessive and unnecessary weight;
- low tire pressure;
- poor transmission shifting or torque converter not locking;
- poor engine tune: compression, plugs, wires, filters, etc;
- leak in fuel system: injectors, lines, filter, tank;
- not filling tank to same point between fill-ups;

The 2001 Town Car with the standard 3.08 axle and 225/60x16 tires will shift up on light throttle at the following speeds:
1st to 2nd at 7 - 10 mph
2nd to 3rd at 18 - 21 mph
3rd to 4th at 33 - 35 mph
and will downshift on a closed throttle:
4th to 3rd at 27 - 31 mph
3rd to 2nd at 15 - 19 mph
2nd to 1st at 9 - 12 mph
There are 4 ways of checking if the torque converter is locking:
- just before coming to a full stop you can feel the torque converter unlock by noting a slight tremor from the trans, but it cannot be felt in my TC;
- you may be able to hear the engine rev slightly in response to slight acceleration when torque converter unlocked but not when it is locked;
- with a tachometer you can see the rpm climb more than the speed when torque converter is unlocked, but the speedometer and tach move in unison when the torque converter is locked;
- a scan gauge can read the PCM and identify when torque converter locked or unlocked.

You will need a compression tester (less than $20) to verify the compression as the primary health indicator of the engine. You will be looking for 3 factors:
- how quickly compression is achieved, should be within 3 of 4 turns with the first turn giving 75% of total;
- how high the readings, minimum should be 100 psi for the engine to start and run, but 150 is fairly typical;
- balance is required from the cylinder compressions for the engine to run smoothly, such that the lowest is within 75% of the highest (if lowest is 100 then highest must not be more than 134).
If you don't know when plugs, wires and filters have been changed in 455,000 miles then change them all. If the plugs are darker than light tan and the fuel and air filters are OK then the MassAir Flow sensor may be dirty giving the PCM a false reading and incorrect fuel injection will result.

For the fuel system you can usually tell with your nose. The best time is after a run when engine is hot and fuel system is pressurized (including the tank - slightly) so put the car in an enclosed garage and check around everywhere with your nose. If you don't smell anything you probably don't have a leak. The fuel pressure is supposed to leak down to zero after a period of time. If you have a fuel pressure gauge you can see how long yours takes, if less than 20 minutes you have a problem.

^-- Above courtesy of ABE @ LincolnsOnline

[Bearfoot]

Another thing most people don't think about but is very important is the catalytic converter. At 455k they should have been changed twice.