If you don't have a vacuum gauge, you're missing out!
 

Just refilled after my first full tank with my new vacuum gauge. Despite cold temps, some wet roads, Santa Ana wind conditions, a little low pressure in one tire, no P&G at all, stop-and-go and ferrying the family around the mountain, I still clocked in at 35.66 mpg, or only .09 mpg below my best summer tank! For the first time, I exceeded 500 miles on a single fill (522.1, to be exact!) Not only am I easily seeing the subtle difference between light-foot and slightly-lighter-foot, I think I'm really helping myself where I hurt most--going up the mountain home each night. In comparison, my previous tank, with nearly identical driving conditions, but with the gauge only installed during the last 70 miles, was 33.34 mpg.

As I mentioned in another thread, I got the Autogage gauge with the four colorbars. I think this helps immensely, as it's easy to see when I'm accelerating well (usually right where the orange ends/green starts is as far as I go) and when I'm going up the hill with the best economy (6 in./hg, right where the red meets the orange.)

Now that it appears I've beaten the leaky clutch hose, I'm going to try P&G again to see if I can really get things cooking, and I can't wait for hot weather so I can try to break 40 mpg!

If you don't have one, get one. It's $38 from Amazon with free shipping, and it installs in 10 minutes. Comparing the last two tanks, mine pays for itself in 3 months at the current rate.

I got a vacuum gauge once, it was faulty, so I returned it for a replacement... never saw the second one.. Ordered from JC Whitney.

I love my vacuum gauge. I constantly monitor it for peak fuel efficiency.

What exactly does a vacuum gauge do?

It measures the vacuum at the intake manifold. As engine power increases, the engine generates less vacuum. The upshot is that a vacuum gauge can show you approximately how much the engine is putting out. In my case, for instance, when normally driving up the hill, I'd see between 0 and 3 inches on the gauge. By adjusting my speed and throttle a little bit, I'm able to climb at about 6 inches at nearly the same speed. Therefore, I'm using less fuel by being very subtle with the go pedal. The vacuum gauge gives me that instant feedback.

*Cough*MPGuino*Cough*Same price*Cough*

*Cough*Hacking up your wiring*Cough* :)

Actually have one; haven't had a chance to put it together yet.

diesel
 

Cough...I drive a diesel...cough...neither one works...cough.

Seriously, neither option works for me. MPGuino is unsuitable for VW diesel , right?

Other options? I got the basic '04 Jetta TDI PD, without the fancy schmancy gauge cluster, so no readout of FE of any kind. I don't feel like doing the junkyard thing to replace the cluster.

I do have very good diagnostic software that lets me snoop through the diagnostic port, but very clunky to try using a laptop while driving.

Finest regards,

troy

When you get it done it will be interesting to crosscheck the data. Let us know how they work together.

1. Why won't a vacuum gauge work for you? Even if you're boosted, you're still in vacuum before the turbo spools, so the idea would be to keep out of boost as much as possible.

2. Upload your program on a small (palm) PDA - they're cheap. Hell, you could get a modded iPod that would accept just about any program that can be run in MS Windows. Anyway, there are diagnostic tools available that allow you to datalog from an OBD-2a/b port.