Contour Enthusiasts Group Archives Forums Modifications Duratec Performance Improving fuel economy

??? 4-5K...

Anything MORE is opening the secondaries? Secondaries open at 3200 WOT or ~3700 any other time. I am confused as to how 4-5K is pushing the opening limit, as I thought they would be open by then, regardless.


Ray

The IMRC opens at 4100rpm regardless of throttle position.

The base load tables do not change. Fuel trim is applied normally under light load.

Like you said, up to 4100 it is throttle position dependent, hence the 4000 part of my explanation. Then the 'up to 5000' part is based on better to have a little more power at light throttle then to floor it at low throttle explanation about fuel economy. Probably should have been a little clearer, but I didn't expect the vultures from the rafters to pounce that quickly.

Perfect example was a rental car I had years ago, a dodge something or other ATX. To get anywhere with it faster than a snails pace I had to floor it until it got up to 40mph where I could finally let off, it was really that slow. THe fuel economy was horrendous and it was a 4 cyl atx! I had to gas up every two days since it was a small tank too. So what I did was turn off the ac and lightly accelerate. It was very slow, like Model T slow but at least the gas mileage improved.

I ended up with better gas mileage in the Contour by using light throttle even at higher rpm, up to a point.
I found that anything 5000 rpm and over would noticeably use more fuel than up to it.

So I'm talking as a three new contour owner over 10 years, my original 95SE that I traded for the 98 SVT in 97 when it came out and of course that one was bought back by Ford because of so many little problems and I got a 99 SVT that has been great. So I've owned an example of each V6 engine setup except for returnless style and I this stuff holds true IMO.

I gotta clean my UIM and LIM one of these days. I am getting pretty dectnt mileage, but its got 180K on it now. Probably never been done. Certainly not by me !

So you are saying that you attained superior fuel mileage by applying moderate throttle input while also maintaining that the engine's revs stay below a count of 5000. Also you noted that when you did go over 5000 rpm your fuel mileage dropped at an increasingly quick rate of change.

I would assume that using more then moderate throttle input would also curtain the fuel mileage gains you were otherwise seeing.




<---takes dagger from back...


On a serious note...

The stock fuel tables would account for that. They get "grossly" rich once you pass 5000rpm.

The stock SVT PCM is commanding {ideally} 12 AFR at 4k. That drops to 11 AFR by 5k which then drops to 10.5 AFR by 7k.

Something like that.

I've driven between Ohio and Wisconsin many times in my Lincoln Mark VIII (4.6 DOHC 280hp V8). I consistently got 26.5 mpg, averaging 75-80 mph. Even though it was a powerful engine moving a heavy car, I got pretty good mileage because it could get up to speed quickly, and once it was there, it didn't have to work hard at all to maintain it.

Another time I took a 2005 rental Taurus (OHV 3.0 V6, ~150hp) on the same trip. It was straining to maintain the same speeds, and I had to keep the gas pedal mashed to the floor when leaving onramps and toll booths to get somewhat decent acceleration. As a result I got 20.5 mpg.

Same thing with my mom's '98 Kia (ATX 1.8l 125hp 4-cyl). When I'd drive it around town, it would get a whopping 17 mpg because I was constantly flooring it.

With my Contour, it's capable of accelerating to my liking without being overworked.. But it feels and sounds so nice that I end up flooring it and shifting at redline all the time anyway.

Those of us with lead foots don't really benefit from driving underpowered cars!

a 4.6 liter blown mustang gets 26mpg on the freeway. Of course im sure there at 1500 rpm at 75mph in sixth gear.

For the record, that MarkVIII has the aerodynamics of an arrow, especially at highway speeds (active suspension)

As for getting the Contour better gas milage, you can try these little tricks:

- SVT Body kit (maybe a Mirko spitter?)
- Lower the suspension
- Free'er flowing exhaust (headers, different cat, and something like Bosal cat back)
- Tune up, cold air, etc.
- Lose any trunk spoiler, front bra, or window vent shades
- Underbody aerodynamics makes a difference, too. Pop rivet on some sheets of aluminum
- Inflate the tires almost to maximum
- Alignment helps, too.
- Drive at or just below the speed limit. Once you are in the top gear, you are just fighting the wind.

Most anything you would do to add power to the engine, makes it more effecient (just keep the same displacement)