1997 Lincoln

If I'm driving about 60 mph and let up on the gas pedal, instant fuel economy only goes up to about 65 mpg. However, if I let up on the gas pedal and put the transmission into neutral, instant fuel economy goes to 99 mpg and the car seems to slow down faster. How do I get the engine to completely back off on the accelerator while I'm coasting. I think this is one of the reasons for the poor fuel economy. The car won't get any more than 24 mpg on a long trip driving 65 mph. Everybody seems to be able to get 30 mpg.

Things done to car:
New fuel filter
New Autolite copper plugs
New COP's
Replaced O2 sensors - Didn't notice any difference
Cleaned MAF sensor
New air filter
Fixed drivers side intake manifold vacuum hoses
Clean throttle body butterfly
Cleaned IAC
Checked IMRC's for binding
Checked Fuel Pressure Regulator for leakage
Check Fuel Pressure at idle
Checked EGR
Checked for leaky injectors
Switched to synthetic oil
Checked that O/D is working and torque converter is locking
Took car in for scan, no codes
Pressurized tires to 41 psi

Only thing that helped a little with fuel economy was new COP's.

If you coast for more then a preset time (around 20 seconds) the injectors will turn off and you will feel more engine braking. I don't think you would want that except while going down long steep hills. I don't think everyone else is getting 30 MPG. I once got 26 MPG on a trip on a flat road with no stops and no wind back when I was still interested in getting good mileage.

Neil

No mention of what year/model the car is. A LSC is going to get a little worse economy due to lower gearing. Perhaps a check of the throttle position sensor, to be sure that when you let off the pedal, it doesn't think your foot is still riding the gas.

Calvin Louie
1989 Porsche 928 S4 - Linen Metallic / Linen

Good point. I do remember getting 28 or 29 MPG on rare occasions in the 95 base but that was going 55.

Neil

Don't understand the increased "engine braking" while in neutral as compared to coast down in gear...there should be NO engine braking when out of gear. I only expect about 25-26 MPG from my '98 LSC with 35 psi inflation. At 41 psi, I would expect a little better mileage though...depending on type/model of tire.

I'm no expert on this car YET, but I'm going to throw my 2 cent in - besider all the changes that you've done;
1. change to K & N Air Filter
2. put on some high performance MSD Coil Packs
3. New Alternator (yes they can die a slow death)
When I made these changes to my 95 base;
1. my performance went up
2. I got my 30 mpg back & that's doing 80 mpr
3. my heating problems went away - now a steady 25% of norm

>I'm no expert on this car YET, but I'm going to throw my 2
>cent in - besider all the changes that you've done;
>1. change to K & N Air Filter
>2. put on some high performance MSD Coil Packs
>3. New Alternator (yes they can die a slow death)
>When I made these changes to my 95 base;
>1. my performance went up
>2. I got my 30 mpg back & that's doing 80 mpr
>3. my heating problems went away - now a steady 25% of norm
>
>

Wow, the fuel economy at 80 mph would be terrible on mine. I get 23 mpg at 65 mph but it goes down quickly after that.

1997 Lincoln LSC