I'll go out on a limb and guess it'll change by -1.75, or 16.21mpg average.

In the same conditions as your 17.96 MPG, I say you'll gain .8MPG to about 18.76 MPG.

I can think of at several reasons why a chip might help my diesel:

The Powerstroke is a turbodiesel with variable turbocharger vanes. Ford has those variable vanes set at a highly restrictive setting at low RPM to keep the boost up. I suspect it's mostly for better throttle response, or perhaps NOx control. At any rate, this high boost condition causes a lot of exhaust backpressure and pumping losses. Opening up the vanes for a given fueling rate will cause lower air pumping losses.

Second, the chip might allow more torque at low RPMs. This would allow the auto tranny to shift into a higher gear.

Third, it might shut the cooled EGR valve. This would both lean out the engine, and reduce the thermal load on the cooling system. The thermostat would close off the flow more and reduce water pumping losses.

Neener

I believe that it also drives up some of the fuel pressure too since that's all controlled by electronics, even on my old '96.

OK, the programmer went in Saturday. I'll keep it in for a month. It's snowing here today, so mileage on this tank will be dreadful. The average of tanks between Jan 11 and Feb 111 will be used to determine the contest winner.

Can you tell any difference in the way it drives/shifts?

So far the shift points seem higher. I've had to feather the throttle to get it to shift into a higher gear.

I've got one of those tuners from Superchips. MPG sucks as usual. 14 is typical. I used to get 17 but after 120k miles, somethings not right. Runs fine except for the stalling caused by the crappy cam sensors!

I had a Western Diesel chip to start with. The best I know of is the https://www.dp-tuner.com/
Everyone on the Powerstroke forums prefers it.

I should have waited to get one of these. You get more tune options. One is an econo tune.

FYI: If you have an AUTO 4R100 trans, set aside $2500 for a new one. The trans is crap and will fail right after the warranty. It can't handle pulling or tuned motors. That's why the 7.3TD is detuned from Ford. It makes the trans last longer.

I think there's a global recall on the cam sensors from 1998 to something very recent. Might want to use Google for that information.

I had some sputtering in my '96, and I replaced it with the '98 and up sensor...less expensive, $30 vs $100, and takes ten minutes to replace. Works great.

OK, the results are in, and the contest is over. Here is my mileage over the past 5 tanks:

miles diesel
627.4 33.6
497.5 29.505
445.3 29.807
490.7 28.244
484.8 29.248
2545.7 150.404

16.92574666
It looks like DRW is the winner. The truck LOST 1 mpg with the chip. I was careful to stay off the throttle too, drafting semis and such! Does ever aftermarket company lie about mileage? I'm returning the Superchips unit.

DRW, send me a private message with an address, and I'll mail you a $25 check.