PCM Learning

[Jackpine]

Originally Posted by PitCritter

I do hand calculate every tank of gas. My numbers since new are on Fuelly if anyone's interested.

I understand the function of Tow/Haul. In addition to using it, I locked out sixth gear since even on flat ground, the engine could not maintain 55mph in sixth. It would shift up and then immediately shift back down. In the interest of saving my transmission, I used fifth as my top gear.

Thanks for the info on my "Snapshot" question. Your answer makes sense.

The referenced PDF is mostly beyond me, I'm afraid, but I do understand the gist of it. It definitely backs up your statement.

Locking out 6th is exactly what you should have done if shifting was happening constantly.

Your "later" fuel economy figures are somewhat amazing. If the Tire Size and Gear Ratio is correct so that your odometer is accurate, you are getting superb gas mileage. Whether or not your in-town mileage will improve is beyond me. I've not seen anything like you describe in my 05.

My truck is mostly used for highway driving and highway towing, so I also cannot comment on the effect of town driving hurting highway mileage.

I WILL say that winds and upslope/downslope driving have an enormous effect on fuel economy. And, if you climb and then descend, it doesn't "cancel out" due to efficiency losses. Anytime you climb, you use more gas.

- Jack

[Power Hungry]

Driving from GA to FL, we will see as much as 22 MPG on our Expedition. Driving back, it will drop to about 19 MPG. Now, this could be in relation to fuel quality between GA and FL, or maybe just differences in trip parameters (overall altitude change, headwinds, traffic, etc.), but it is pretty consistent every time we travel.

As noted, the ECM does tend to relearn driving characteristics (aggressive driving, moderate driving, loaded, unloaded, etc.) and will readjust fuel and timing curves to meet the needs of the vehicle.

[PitCritter]

I appreciate all the input.

My rear end is 3.55. My tires are 20s. My speedo (vs GPS) is accurate to within at least 2%.

If anyone's actually interested, my mileage numbers are all at Fuelly.com. Search on username PitCritter. I've set up different accounts for tracking towing vs. non-towing.

Now...how 'bout that tuner for my '11?

[Power Hungry]

Originally Posted by PitCritter

Now...how 'bout that tuner for my '11?

You need to lean on Edge about that. Actually, I think they are working on it. I'll have to check.