We have an 06 Envoy with the Atlas 4.2 Straight 6, 2wd. The fan clutch is stuck on it for the second time. I'm going to convert to electric fan which requires a tune-out of the stock fan setup. Since I have to get the ECU tuned I'm wondering if I should get a 93 octane tune put in for S&G's?

This car, stock, doesn't break 20mpg on regular gas. I'm curious if the MPG would go up or down or stay the same on a 93 octane tune? I don't think I'd do it if the MPG got any worse.

I could be convinced to put better mufflers on it, but I won't do a full exhaust. I'd probably leave the stock airbox on it as well.


P.S. I fully realize that my right foot will detail exactly how much gas mileage I get, but I'm curious anyway.

Your MPGs will probably go up, but not enough to offset the ~$.70/gal increase in fuel costs.

I'm not really worried about the cost increase. It's not a financial decision, really. I just don't want the MPG of this turd to go from 17 to 12 AND have to pay more per gallon.

They shouldn't decrease.

I had one tuned way back in the day. Best MPG gain was through remapping the torque management in the TC/Transmission. Even with a increase in HP from the engine tune, the overall MPG went up.

Sweet. Thats good news.

silverado_lover said:

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Tune and muffler? **** son, drop in a 5.3 while you're there

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dis here.

silverado_lover said:

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Tune and muffler? **** son, drop in a 5.3 while you're there

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****, might as well supercharge it while you're doing that

sts7049 said:

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a tuned envoy... that's a first

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They have a stupid crank-driven fan which has a computer controlled clutch that likes to **** the bed. The fix is e-fans from a camaro and a tune-out of the clutch control. Got to send off the ECU anyway, might as well get some more chooch out of her while it's there......