Vacuum gauge AND ScanGauge

[JRMichler]

I added a vacuum gauge to my truck in May. I did this to get real time vacuum feedback because I was not satisfied with the time delayed ScanGauge MAP display.

The Canyon throttle by wire program has a real PITA feature in it. When between about 12 to 15 In Hg vacuum, I can lift the gas pedal enough to increase manifold vacuum by one to two inches. The vacuum increases, then the program takes over and opens the throttle plate just enough to put the manifold vacuum back where it was. If I reduce throttle slowly, I can raise the gas pedal about an inch with no change in manifold vacuum.

The real time feedback from a mechanical vacuum gauge makes it possible to get better control. This may explain why my mileage for the last 2000 miles is 38.0 MPG.



I bolted a small piece of aluminum to the gauge cup base, then added a piece of sticky back Velcro. Another piece of sticky back Velcro on the dash, and the gauge was mounted. I put the plastic vacuum line inside a piece of black shrink tubing because previous experience showed that sunlight will eventually destroy the tubing.

[Cobb]

Thanks for sharing.

[JRMichler]

Well, the summer gas mileage season is over. I drove 3414.0 miles and burned 89.42 gallons, for total summer MPG of 38.2. That compares to the summer 2013 average of 36.0 MPG, and the summer 2012 average of 37.1 MPG.

Summer 2012 had warmer weather with more tailwinds, and summer 2013 had worse weather than summer 2014. I believe that the better feedback of the vacuum gauge, compared to the time delayed feedback of the ScanGauge, is worth at least 1.0 MPG and possibly slightly more.

[accord_minded]

Agree with the observations in this thread. I saw a small, but definite MPG increase by having the immediate and fine-grain feedback of a vacuum gauge supplementing the SCangauge in my car.

[JRMichler]

Gas mileage for winter 2014-2015 is 30.04 MPG. That's 4.7% better than my winter 2013-2014 mileage of 28.68 MPG. Both winters were colder than average for this area, and had more than the fair share of headwinds. Both winters were noticeably colder than the several previous winters.

Last summer's mileage was 4.5% better than the average mileage for the two previous summers.

I credit the better feedback from the vacuum gauge, as compared to a ScanGauge, with at least a 4% improvement in gas mileage.

[mikeyjd]

I need to ad a vacuum gauge!

[gone-ot]

Vacuum gauge = excellent visual feedback of throttle "control" as it happens.