Altitude Seriously Affecting Gas Mileage

[GoSlo]

This is an "issue" I've been dealing with on the TriGlide since I've had it. I live at just over 5,000-feet in elevation. I have tuned the trike (PowerVision) and a done a few other things to run well, and it runs strong when we head to the mountains with elevations up to or over 10,000 feet and I average 34-35 MPG. It's when I go down in elevation that the problems begin. Here's the latest example:

Went on a three day ride last week at an elevation of 3,300 feet. My gas mileage fell to 26.5 MPG on averaqe. Then on the return trip home, the higher the elevation got, the better my gas mileage got. Riding on the highway, doing 75 at elevations above 5,000 feet, it was back to 34.5 MPG. The worst I've seen my mileage go was on a trip to the Florida panhandle where it dropped down to 24 MPG or so. It's not tire pressure because I check that. It just seems as though for every 1,000-foot drop in elevation, my gas mileage goes down 2-3 MPG.

So my question is this...does anyone else have this problem? The only solution I can think of is to ride down to an elevation of 3,000, run some tunes and save it as the tune to use at that elevation and then do the same for an elevation of 1,000 feet. Then I could swap out to the 'correct' tune for where I'm riding to at least get closer to the right tune and improved gas mileage. I'm not a "tune guy" or have any other engine abilities, so this is just a guess on my part.

[Old Road Dog]

I think your on to it. Remember the old carburetor drag racers?They would have to re-jet when racing at sea level in Daytona and then again in Denver.

[NC Triker]

I have a 2017 TG and live on the coast in NC. Filled my tank yesterday and computed my mileage. 37 mpg at sea level. Most of the miles were highway with no stops. I don't know why you are losing so much MPG at lower altitudes.

[Jack Klarich]

How did it do with the stock HD map?

Is it running way to rich with the tune in your Pv?

Have you re ran your stock tune to compare?

[GoSlo]

How did it do with the stock HD map?

Is it running way to rich with the tune in your Pv?

Have you re ran your stock tune to compare?

My stock tune was a dog, like everyone else's. Too restricted. I have not re-run my stock tune because that would be taking me backwards in what I've done to make it run cooler and more efficiently. I'm getting a new tune from Kevin at DK to start with and will do tune runs starting with that. Hopefully, that will help.

[Jack Klarich]

My stock tune was a dog, like everyone else's. Too restricted. I have not re-run my stock tune because that would be taking me backwards in what I've done to make it run cooler and more efficiently. I'm getting a new tune from Kevin at DK to start with and will do tune runs starting with that. Hopefully, that will help.

I put a stock air box back on and original tune just for grins

Yup, sure enuff, mileage went down and heat went up

[FuzzyWuzHe]

The only solution I can think of is to ride down to an elevation of 3,000, run some tunes and save it as the tune to use at that elevation and then do the same for an elevation of 1,000 feet. Then I could swap out to the 'correct' tune for where I'm riding to at least get closer to the right tune and improved gas mileage. I'm not a "tune guy" or have any other engine abilities, so this is just a guess on my part.

I did something similar. I live in Grand Junction and like to ride to Mesquite, so, I go from 5100 feet to 0 o that trip. On my 15 tri I did a 20 minute tune run the first time I went there. So I can stop for gas in Cedar City, switch to the low altitude tune and switch back on the way home. Gas mileage did improve with the Low altitude tune, but, didn't get to the 35-37 I was getting in Junction. Not sure why. With the low altitude tune I was getting like 30-32.

[GoSlo]

I did something similar. I live in Grand Junction and like to ride to Mesquite, so, I go from 5100 feet to 0 o that trip. On my 15 tri I did a 20 minute tune run the first time I went there. So I can stop for gas in Cedar City, switch to the low altitude tune and switch back on the way home. Gas mileage did improve with the Low altitude tune, but, didn't get to the 35-37 I was getting in Junction. Not sure why. With the low altitude tune I was getting like 30-32.

Thanks, that's good to know that it at least sort of worked for you. 5 MPG less would be better than the 10-12 I'm losing now. Guess this means I have to ride some more to lower elevations and do some tuning runs.

[DK Custom Products]

This is an "issue" I've been dealing with on the TriGlide since I've had it. I live at just over 5,000-feet in elevation. I have tuned the trike (PowerVision) and a done a few other things to run well, and it runs strong when we head to the mountains with elevations up to or over 10,000 feet and I average 34-35 MPG. It's when I go down in elevation that the problems begin. Here's the latest example:

Went on a three day ride last week at an elevation of 3,300 feet. My gas mileage fell to 26.5 MPG on averaqe. Then on the return trip home, the higher the elevation got, the better my gas mileage got. Riding on the highway, doing 75 at elevations above 5,000 feet, it was back to 34.5 MPG. The worst I've seen my mileage go was on a trip to the Florida panhandle where it dropped down to 24 MPG or so. It's not tire pressure because I check that. It just seems as though for every 1,000-foot drop in elevation, my gas mileage goes down 2-3 MPG.

So my question is this...does anyone else have this problem? The only solution I can think of is to ride down to an elevation of 3,000, run some tunes and save it as the tune to use at that elevation and then do the same for an elevation of 1,000 feet. Then I could swap out to the 'correct' tune for where I'm riding to at least get closer to the right tune and improved gas mileage. I'm not a "tune guy" or have any other engine abilities, so this is just a guess on my part.

When I read your post I think of a few things....I may be wrong, or missing something, but here are my thoughts.

1. A drop of 10-12 MPG is excessive

2. When you are in higher elevations, it may not be only the elevation having an effect. To some degree, possibly a large degree, it could be due to the cooler temps at the higher elevation. The cooler our engines run (as long at 190 degrees) the better they run, and get better MPG.

3. A properly operating EFI does not need a different tune for different elevations. The o2 sensors detect the lower oxygen content at higher elevations and make proper adjustments to the tune, and vice versa, at lower elevations they detect the higher oxygen content and make adjustments.

Since there is a lower oxygen content at higher elevation the ECM adjusts the fuel and feeds less of it, that is one of the reasons you will get better MPG up higher.

There may be other things going on...hard to know without looking at the engine. Hopefully the tune I sent you will work a bit better.

In general, for Twin Cam's, the following is true (M8's are different, they do get better MPG)-

At higher elevations it is normal to get 35-39 mpg at speeds of 65-75. The same bike at sea level, on a warm day, going under 70 mph will get 32-34 mpg, going 75 it can drop to 29-32 mpg. But, if you add in a headwind, the stronger it is, the worse the MPG...I think the worst I've gotten was around 22 mpg at sea level, going 70-75 mph into a 25-30 mph headwind.

Anyway, some things to think about. Higher elevation will always give better MPG (everything else being equal), Cooler temps will always give better MPG (everything else being equal), so you are getting both of those when you're at 7,000 or 10,000 ft. I am not sure it would account for a 12 mpg difference (if everything else is equal) though.

One last thought added....you should be able to do an auto-tune at any elevation and have it come out the same as if you'd done the auto-tune at a different elevation...IF everything else is equal, which, of course, it never is. So doing some auto-tunes in higher elevations with the riding style you use there, and then a different batch of auto-tunes at sea level (saved to a different "sea-level" tune) with the riding style you use there, will give you two different tunes that were dialed in for your different circumstances and riding styles.

Kevin

[GoSlo]

[QUOTE=DK Custom Products;577821]When I read your post I think of a few things....I may be wrong, or missing something, but here are my thoughts.

One last thought added....you should be able to do an auto-tune at any elevation and have it come out the same as if you'd done the auto-tune at a different elevation...IF everything else is equal, which, of course, it never is. So doing some auto-tunes in higher elevations with the riding style you use there, and then a different batch of auto-tunes at sea level (saved to a different "sea-level" tune) with the riding style you use there, will give you two different tunes that were dialed in for your different circumstances and riding styles.

Kevin,

I loaded the tune you sent me and took a short 70 mile ride up into the mountains. Yes, it was a little bit cooler, but my gas mileage improved about 5MPG over the tune I was running, so thanks. You made good points about elevation and it's effect on mileage. I think I will take a trip to a lower elevation (3000-4000), check my mileage there, run some auto-tunes and see if it helps.

Thanks again. The tune I was using now seems like it was way off. The occasional backfiring stopped, MPGs increased and it ran a little cooler too....all good things!

Have a great trip!

[FuzzyWuzHe]

As I stated ... I had a similar experience with sea level mpg and tuning at that level did make it better, although not as good ... frankly, I can't explain it. But when I go to Mesquite next time, I will tune for that altitude and switch to that tune. My experience is a 5200 foot drop, maybe that makes a difference.

As a side note ... LOL ... adjusting my speedo to get it accurate (0.1 miles off on a hundred mile run), has really messed with my mpg's I used to gain 0.5 miles on 10 miles (or 5 on a 100 mile run) so, if i ride 220 miles and use 4.5 gals, I get 48.9 mpg. In reality, I went 200 miles and used 4.5 gals or 45.9 mpg ... it's a curse to want things right.

[DK Custom Products]

Kevin,

I loaded the tune you sent me and took a short 70 mile ride up into the mountains. Yes, it was a little bit cooler, but my gas mileage improved about 5MPG over the tune I was running, so thanks. You made good points about elevation and it's effect on mileage. I think I will take a trip to a lower elevation (3000-4000), check my mileage there, run some auto-tunes and see if it helps.

Thanks again. The tune I was using now seems like it was way off. The occasional backfiring stopped, MPGs increased and it ran a little cooler too....all good things!

Have a great trip!

That is great news on the better MPG. That tune I sent you has the base/foundation of a tune that I got from Fuzzy. He spent countless hours on it getting it "just right".

For best possible results, I would load two of them into your Power Vision...one that you auto-tune at lower elevations and the other that you auto-tune at higher elevations.

Would be interesting to see how differently they turn out and how they perform.

Kevi