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