Just Got My 6.0 FICM Tuner - Interesting

[kghenson]

I had decided that before got the tuner I would baseline mileage. Each morning I drive the same 13 mile route on a local interstate so at the beginining of the drive I set cruise control and re-set the computer. ( I have hand checked the computer and it is about .5 MPG off ) This is a bone stock 2006 Crew Cab 4x4 with 4:10 rear

At 60 I get 17.8, 65 15.8, 70 14.0 and 75 12.8. Interesting that there is a 5 mpg difference between 60MPH and 75MPH.

This weekend my FICM tuner showed up from PHP. easy instructions, installed in minutes. Yesterday and today I made the first 2 test runs with the FICM set at Economy. At 65 MPH I got 15.4 and at 70 I got 14.0. So at 70 no change and at 65 worse. My in-patient brain wants to skip to +40 setting but I will continue the test runs at 60 and 75.

As I get the results I will continue to post them.

Some good news my ECT and EOT usually run at 12 to 8 degrees apart and my FICM voltage at start is 47.5! More Later but so far I would have to ask PHP why even load the "Economy" FICM tune, lol.

[jesilvas]

I know you used the PCM for the MPGs untuned, but what about tuned?
Also, what is your diff ratio? I bet your RPMs between 60 and 75 mph goes over 2k.

[kghenson]

All mileage is from the truck's computer, is that what you are asking? And the diff is 4:10 so yes at 65 and above I am above 2k rpm

[Dave]

Go straight to the 40. I saw a 2mpg increase hand calculated with it

[jesilvas]

Yea, I was saying that the truck PCM may not be able to accurately calculate MPGs once it's tuned. I wouldn't trust it until you compare the two like you did un tuned.
2k RPMs is like magic. I've gotten about 17mpgs keeping it right at 2k and below as often as I could. Go above it, and forget it.

[Dave]

Originally Posted by jesilvas

Yea, I was saying that the truck PCM may not be able to accurately calculate MPGs once it's tuned. I wouldn't trust it until you compare the two like you did un tuned.
2k RPMs is like magic. I've gotten about 17mpgs keeping it right at 2k and below as often as I could. Go above it, and forget it.

Exactly with a tuned FICM in the mix the on dash reading is off when stock tuning is in place on the ECM

[kghenson]

Originally Posted by Dave

Go straight to the 40. I saw a 2mpg increase hand calculated with it

Yeah I get that but I am going to run the test first. I plan on doing the calcs for Econ, +40, +80, and Herc. Since I don't flog the truck I'm OK with doing Herc with stock studs but I think after all the testing I will stick with +40 or +80 based on which one has the best numbers.

I'm pretty sure +40 will be my home eventually

[kghenson]

Originally Posted by Dave

Exactly with a tuned FICM in the mix the on dash reading is off when stock tuning is in place on the ECM

You did that test already so if at +40 I see similar results to what you got then I will be on the rigth track. But the observation that I need to check PCM error at each setting is a valid point. So after I run the numbers I will hand calculate a tank at each setting to see what correction facter needs to be added. I know at stock the PCM reads .5 MPG high.

Thanks for the excellent feedback!

[Lilfarmrboy]

Personally I would use only hand caculated numbers if you really want a great test instead of the lie-o-meter. Or you could use that fuelly.com which is a great site to keep track of MPG.

[Dave]

Im using my lie o meter now between the PHP ECM and FICM tune.

Its only about .1 mpg off from hand calc