Turbo and MPG...

[dhirocz]

Getting the hang of driving for mileage. I have to say, it's certainly different than 'set it and forget it' with the cruise, but so far I'm definitely seeing a difference.

Last week I installed a new paccar CAC. Saw another increase in mileage. I'm right at 13mpg driving @ around 3 psi of boost, 58-60 mph, empty tank trailer. Not a big mileage difference bobtail...not to bad considering I'm running on knobby tires.

Question is, while I'm loaded, my mileage is all over the place. I normally run 78-80k loaded, but it doesn't matter what I do...mountains, flat, slow, fast, not alot of difference like there is when I'm unloaded.

I'm still getting VGT out of calibration errors, so at 710k now, a step in the VG arm, and a stock turbo and actuator, I'm thinking the ECM is loosing it's ability to control the turbo...it's getting close to that time. Sometimes it pulls fine up a hill loaded at 12 psi, other times it wants 20+ on a similar hill. I don't think I'm seeing the problem unloaded because I'm hardly using the turbo. Thoughts?