Fuel Economy, Hypermiling, EcoModding News and Forum - EcoModder.com - View Single Post - Cruise Control (with MPG sensitive logic)

mjspiess · 04-23-2012, 10:28 PM

What you are seeing in my videos is just an MPGuino indicating constant MPG and speed fluctuating based on elevation changes, wind, etc. With the Ford MAP sensor in place, the cruise control is getting feedback from the MAP sensor instead of the VSS, so it "locks" in the load of the engine and tries its very best to maintain that specific load just as it would if it was hooked up to the VSS.

Today was the first true test as I went to work and it's 95% highway. Minimum speed limit is 55 mph & PSL is 70 mph. I typically set my cruise at 57 mph. During the longest steepest hill, my speed would drop to 55 mph & instant mpg would drop to 34 mpg.

So once I got up to 57 mph, I steadied the throttle and hit set at 53 mpg. To my surprise, my car actually slowly sped up to 62 mph and pretty much held 62 mph at 53 mpg. MPG fluctuated between 52-55 mpg and speed fluctuated between 59-62 mph. During the longest steepest hill, my speed only dropped to 56 mph and mpg only dropped to 48 mpg. Max speed was 71 mph heading down hill.

As I exited the highway, my trip MPG was just over 52 mpg. I had to go to a different school this morning for work, so I had more city driving than usual. It ended up being 51.51 mpg for the trip. Not excellent, nor bad.

The question is...What would have been my trip average had I just used normal cruise and set the speed at 57 mph like I usually do? During usual cruise, my MPG would get as low as 34 mpg on the longest steepest hill and well into the 100s on the down side of the hills with stretches in the 40s, mainly in the 50s, some in the 60s and on rare occasions some in the 70s. It seems to me, it prob. all averages out.

I think the cruise must take RPM into consideration because it held my speed way better than I had imagined.

Also, while cruising, if I hit Accel/Resume my speed MPG locks in a few MPG low and when I hit Set, MPG locks in a few mpg higher, very similar to speed when normally hooked up. That is pretty cool when you're trying to figure the slowest speed/highest MPG allowable for the current road conditions. For my current route at 55 mph limited speed limit, it looks like 53-55 mpg is prob. going to be the optimal setting without having to "over ride" the cruise on the hills.

On my way home tonight I had 15-25 mph head wind. I was able to set the cruise at 49 mpg. It fluctuated between 47-51 mpg and I maintained about 56 mph with drops down to 53 mph and peaked at 71 mph. Trip average was 48.84 mpg.

Despite the head wind, the cruise still managed to do quite well.

04-23-2012, 10:28 PM	#154 (permalink)
mjspiess EcoModding Lurker Join Date: Nov 2009 Location: Lansing, MI 48917 Posts: 70 The Blue Bomber - '95 Geo Metro 90 day: 52.09 mpg (US) Thanks: 3 Thanked 8 Times in 6 Posts	What you are seeing in my videos is just an MPGuino indicating constant MPG and speed fluctuating based on elevation changes, wind, etc. With the Ford MAP sensor in place, the cruise control is getting feedback from the MAP sensor instead of the VSS, so it "locks" in the load of the engine and tries its very best to maintain that specific load just as it would if it was hooked up to the VSS. Today was the first true test as I went to work and it's 95% highway. Minimum speed limit is 55 mph & PSL is 70 mph. I typically set my cruise at 57 mph. During the longest steepest hill, my speed would drop to 55 mph & instant mpg would drop to 34 mpg. So once I got up to 57 mph, I steadied the throttle and hit set at 53 mpg. To my surprise, my car actually slowly sped up to 62 mph and pretty much held 62 mph at 53 mpg. MPG fluctuated between 52-55 mpg and speed fluctuated between 59-62 mph. During the longest steepest hill, my speed only dropped to 56 mph and mpg only dropped to 48 mpg. Max speed was 71 mph heading down hill. As I exited the highway, my trip MPG was just over 52 mpg. I had to go to a different school this morning for work, so I had more city driving than usual. It ended up being 51.51 mpg for the trip. Not excellent, nor bad. The question is...What would have been my trip average had I just used normal cruise and set the speed at 57 mph like I usually do? During usual cruise, my MPG would get as low as 34 mpg on the longest steepest hill and well into the 100s on the down side of the hills with stretches in the 40s, mainly in the 50s, some in the 60s and on rare occasions some in the 70s. It seems to me, it prob. all averages out. I think the cruise must take RPM into consideration because it held my speed way better than I had imagined. Also, while cruising, if I hit Accel/Resume my speed MPG locks in a few MPG low and when I hit Set, MPG locks in a few mpg higher, very similar to speed when normally hooked up. That is pretty cool when you're trying to figure the slowest speed/highest MPG allowable for the current road conditions. For my current route at 55 mph limited speed limit, it looks like 53-55 mpg is prob. going to be the optimal setting without having to "over ride" the cruise on the hills. On my way home tonight I had 15-25 mph head wind. I was able to set the cruise at 49 mpg. It fluctuated between 47-51 mpg and I maintained about 56 mph with drops down to 53 mph and peaked at 71 mph. Trip average was 48.84 mpg. Despite the head wind, the cruise still managed to do quite well.