Driving Mountain

[Gary Palmer]

Hello, all:

I am driving a 89 Honda Wagovan, with a 1.5L DPFI and 5 speed.

I had a very interesting and surprizing experience with driving in the mountains, earlier this week. I am not quite sure what to make of my experience, but I wanted to post it, FYI as well as see if anybody had any thought's.

What I did was I drove about 50 mile's, from sealevel, in Ventura, to about 5500 feet at Mount Pinios, in Ventura County, CA.. In driving up the mountain I kept my car in as high a gear, mostly 5th, with a fairly light peddle, driving about 35mph. Coming back down I tried "Codfishing" going down the mountain, in 5th gear, mostly, ignition off. I had some sections where I had to turn on the ignition to get over a slight grade, or thing's like that. I drove about 35mph, coming back down, until I got back into where I was encountering traffic and I didn't have enough of a grade to keep my speed up.

What I was expecting was that I might get fuel use similar to when I'm normal driving. However what I seemed to get was what I perceived to be the use of about 1/3 less gas than I would have normally expected for a 100 mile trip. I would have thought with the fuel used to climb the hill it wouldn't be possible to "break even" in terms of how much fuel I used, but instead I appeared to use less than I would have normally even used, in driv ing 100 mile's.

Do any of you have any thought's or idea's on what, why or how this occurred, or do you just think I'm "nut's"?

Like Compaq, I don't have a scangauge, so at the moment I don't have any better information than what I've described, but my apparent results were not at all what I would have expected.

Thanks, Gary

[krousdb]

It is perfectly reasonable to use less gas in that case. Climbing mountains puts your engine in it's most efficient mode. Engine off is the most efficient of all, infinate MPG. Driving on flat surfaces puts your engine under light load, where it is less efficient. Hills/mountains are good as long as you don't have to use your brakes on the way down.

[Gary Palmer]

Is that a part of what you are doing when you drive, to get the mileage you do?

[basjoos]

As long as the uphills aren't so steep that you have to drop to lower gears, you don't have to use braking (friction or engine) on the downhills, you don't encounter too many curves (increases your rolling resistance) and your speed doesn't get too high on the downhill coasts, you will always get better mileage on hilly terrain. I always get better mileage in the rolling Piedmont of SC than I do on the flat coastal plains. My mileage in the NC mountains depends greatly on how steep the uphills are, how many miles of "twisty-turnies" I have to drive, and how many downhills I have to use engine braking to control speed on.

[krousdb]

Yup. I need the hills to get good FE. The key is finding a route where you don't have to use your brakes. That means stop signs/lights at the top of hills, not the bottom. Ideally, you want to climb steep hills and on the way down you want them to be more gradual for the best FE. Gradual climbs and steep donwnslopes are not as good.

[Compaq888]

word of caution, I think scangauge only works on obd 2 cars. I know for sure you have obd 0 or 1 because your car is a 89

[SVOboy]

He has preOBD, unofficially known as obd0, running a pm5 ecu, I'd say.

He'd have to convert to MPFI and an electronic VSS to use the MID.

[Gary Palmer]

Originally Posted by Compaq888

word of caution, I think scangauge only works on obd 2 cars. I know for sure you have obd 0 or 1 because your car is a 89

Compaq888: You make very valid observation, thank you. I had been thinking in terms of the utility of the tool, but you are totally correct, my electrical is OBD 0--- and I am really glad I didn 't purchase a tool and then be reminded. Thanks!