Cruise Control (with MPG sensitive logic)

[IndyIan]

I've been in cars with badly running cruise that did the pulse and glide automatically! I imagine any of the old mechanical systems could be tweaked to do this. I don't think that there would be any advantage though at a manual trans car would still have the engine braking on the glide. Maybe if you had an auto trans that pulsed in a lower gear and then glided in top gear it might be worth while.
Ian

[JohnnyGrey]

If you have to do a total system you would have a minimum and maximum speed. if not i would supose you would know you are going to slow. But that is the whole purpose IS to slow up going up hill. Do you have a scangauge. if not you wouldnt understand what maintaining a mpg setting details.

Yes, I do have a Scanguage, and in PA, we also have some fairly steep grades that are miles long. While I can easily hit 38 MPG on the entire trip, it is absolutely impossible to maintain even 30 MPG in any shape or form for a certain 1.5 mile stretch. Trust me, if you try to maintain cruising MPGs up extended hills, you will have to slow down to a stop. Your way only works if your car's momentum is enough to put you over that hill.

With hills like these, I stay in 5th and give it about 80% throttle to maintain speed. A greater percentage of the fuel I burn gets turned into motion at higher loads, so I take advantage of it.

Also realize that if I were to maintain 38 MPG instead of the infinite MPG I get going down that hill by laying off the throttle, I'd soon be at 110 MPH.

Maintaining a certain MPG is pointless. You'll be able to average even higher MPGs by using moderate throttle up hills and zero fuel down hills. There's nothing wrong with gassing it up hills if you know you'll be able to coast down the other side without riding the brakes. Take a look at a BSFC map sometime.

[Who]

One of the better aftermarket models (Rosta?) has adjustable gain... Set the gain low and there you go.

Different cruises are different.

On our Accord stick the cruise is really course and aggressive compared to the Santa Fe. In normal slower traffic situations engaging the SF's CC always seems to do better according to the ScanGauge iMPG than my right foot for some odd reason - unlike the Accord. That's okay, because I'd rather tap buttons than press a pedal.

[guitarterry]

wow i didnt know there would be so many people who would put in their two cents as to why it wont work. I guess there is some people who cant take over once the cruize is set, even if it had a minimum and maximum speed. i am sorry some people have mountains, But i drive 100 miles a day with just small grades. I just try to keep my auto metro on 52 mpgs. so far my milage is skyrocketing with this system. But it is har to constantly monitor the gauge. a system to set and forget is what we want, keep the negativity down.

[dremd]

Adjustable gain is cool, my Dad's last van (92' E-350 with 460) had an after market cruise + factory cruise. The After market cruise had the Gain CRANKED as the previous owner was pulling a 42 foot (yes that's correct) camping trailer with it. When he used the Aftermarket he'd get 9.5~10 mpg @ 70 (loaded) and with the Factory cruise he would get 11.5~12 @70 (loaded). Pretty significant gain.

The van he had before that (84 Dodge 250 360 engine) had a cruise that would best be categorized as weak, it would essentially DWL, until you dropped to 8 or 10 mph below set speed, then go 90% throttle. In retrospect that was a good setup, but at the time we thought it just sucked.

[IndyIan]

Originally Posted by guitarterry

wow i didnt know there would be so many people who would put in their two cents as to why it wont work. I guess there is some people who cant take over once the cruize is set, even if it had a minimum and maximum speed. i am sorry some people have mountains, But i drive 100 miles a day with just small grades. I just try to keep my auto metro on 52 mpgs. so far my milage is skyrocketing with this system. But it is har to constantly monitor the gauge. a system to set and forget is what we want, keep the negativity down.

Hi Terry,
I am curious what you are doing with your cruise now? Is it normal cruise control you are using? Is it different than pulse and glide in gear?
I just got my scanguage and it is an eye opener, the rate of fuel used accelerating and climbing any sort of grade. So now I do watch and try to keep it below 12L/100km climbing hills when I can and EOC down the other side.
Ian

[guitarterry]

I am using the old foot cruize. But as you can see by using the scangauge is your mpg goes up and up as you get use to holding a constant gas useage, i set my gauge to mpg and try to maintain 50 mpg. as you can see from my fuel log it is working great. I notice that you can be driving say 55 mph and getting 45 mpg, with just a minute backing off of the throtle, the mpg's go up to 50, but speed stays the same. its like free mpg's. but if i was doing a mpg cruize control or a constant throttle. i wouldnt get the same results.

[8307c4]

I do agree, current cruise controls are not as effective as they could be...

The worst part is when the car starts to go uphill first it loses some speed then the cruise OVER reacts, every single unit I have ever used does this, just some are worse than others.

But I'm not really sure how we'd address this issue...
How is the CC supposed to know about an approaching climb?
I think, however, possibly some type of digital level gauge could send 'angle of inclines' information to the CC... This of course would be affected by acceleration and deceleration but then if the CC is active this could be compensated for since our foot isn't doing it.

What I am getting at, is if the car is climbing the CC should at this point merely attempt to maintain speed (most CC's try to get back to the set speed even while still climbing)... Even if it has lost a few mph's it shouldn't try to regain this until things level out some at which point the CC could THEN regain the set speed.

A little smoother on the throttle, basically.

[diesel_john]

jpgmtech
How about if the driver can adjust the delta, and the gain. We need to incorporate the driver's ability to fore see what is going to be needed up ahead. Perhaps a switch to select vacuum controlled or speed controlled. A constant 5 inches of vacuum would put you pretty far up the hill until you needed to intervene with your foot. I would like to limit the throttle position so as to not downshift the transmission or unlock the converter unless i intervene with my foot.

[IndyIan]

Originally Posted by guitarterry

I am using the old foot cruize. But as you can see by using the scangauge is your mpg goes up and up as you get use to holding a constant gas useage, i set my gauge to mpg and try to maintain 50 mpg. as you can see from my fuel log it is working great. I notice that you can be driving say 55 mph and getting 45 mpg, with just a minute backing off of the throtle, the mpg's go up to 50, but speed stays the same. its like free mpg's. but if i was doing a mpg cruize control or a constant throttle. i wouldnt get the same results.

I see what you are talking about now, I have noticed the same phenomenon in my tracker but I have basically no flat roads on my commute so its hard to see what is going on as my instantaneous mileage moves around alot even with constant throttle postion. Also the areo drag is quite high so backing off a little results in lower speed almost right away.

I can see though having cruise that tries to optimize mpg's would help abit, I'd think it would be possible to add some "intelligence" to help, sounds like a good college electronics project!
Ian