33.7 to .. 4̶6̶.̶0̶ .. 60.6 mpg!

[Fat Charlie]

I don't like that rough shift you mentioned in your first post, although it could just be that it wants you to match revs a bit before engaging. That's fair enough, and blipping the throttle to pick it up to driving speed is still much better on gas than engine braking the whole time.

Don't do anything you're not comfortable with. No sense damaging anything here, but if the problem persists, get it checked out. A trans problem isn't going to go away just because you stop doing what helped you notice it, and ATs are evil black boxes that hide mysterious ailments.

[j12piprius]

@elhigh, thank you! I'm quite happy with the ultragauge!

@Old Mechanic, I used the brakes only once the first 126.3 mile trip, at a stop sign, and was barely moving when I used them. The DFCO is working quite well. I basically just counted to compare DFCO with neutral, got about the same count and figured they were about the same, though coasting in neutral "feels" like it's gliding more easily. I will aim to incorporate both of them from now on.

@Fat Charlie, matching revs might be the issue as, other than speed shifting, I don't understand that yet and don't do it at all. Shifts from gear to gear are fine, but starting from a stop or shifting from neutral are rough.

[j12piprius]

Yesterday I added an upper grill block made from a plant pot, and a 60% lower grill block made from a smaller one, then set out on the upward (+325 ft) 126.3 mile trip with the goal of bettering my 41.8 mpg from last week.

The grill blocks resulted in much better acceleration and coasting, and my mpg gradually increased throughout, probably due to terrain. I did coast much more in neutral this trip, though it appeared to only occasionally give any advantage compared to P&D, which I continued to rely on the most.

The overall result is an improvement to 48.3 mpg!

I'm hoping to add wheel covers before the return trip 2 days from now, and will hopefully improve the 46.0 from a week ago.

[digital rules]

Have you calibrated the Ultragauge? Out of the box, both units are ~10-15% optimistic.

My new Scangauge was showing a huge improvement, but after calibrating the numbers are now more realistic. Still a great tool for improving habits, but not a 10-15 MPG gain. (Not yet anyway) I still calculate the old fashioned way for confirmation.

[UltArc]

Temperature may also be a factor.

[j12piprius]

The Ultragauge was within 1% for two fillups of the tank, so I'm using the default.

Average temp the previous trip mostly stayed right at 188.6, with a high (that I noticed) of 194.

I was concerned at the start of this trip as the temp got up to 199 in 3 miles, but then it stayed between 199 and 205 the rest of the way, including the long climb in the middle. Even when climbing, it would go to 205 then come back to 199.

I'm a little concerned about the 10 mile steeper climb on the return trip of 4 to 7 percent grade.

[UltArc]

How are you still alive!? Your tires didn't melt?!

(I meant exterior temps, as in the regular temperature outside. In Ohio, one day difference can mean 30 degrees and snow.)

[j12piprius]

Outside temps are moderate here for most of the year, in the 70 to 60 range at the time of my trips. Is mileage better when it's warm?

Based the last cooling system temps, is the radiator in danger of overheating on a 4 mile 7% grade, or should I just try it and see what happens?

[UltArc]

Mileage is better when it's warm. Air is less dense, easier to travel through. Also, less overall parasitic loss to get over. Think about working out on a cold day, vs a warm day.

How much warming up and prepping is needed when you have to trudge through 6 inches of snow in 5* weather? What about if it's a solid 80 degrees? The joints, and fluids are flowing better and faster at a moderate temperature than colder- works the same for our cars.

[j12piprius]

I didn't add anything else and set out on the downward (-325 ft) return trip this morning, aiming to better the 46.0 from a week ago. This time I incorporated eoc instead of leaving the engine on, and the shifting was the same, but it helped as I saved the fuel that was otherwise wasted during coasting.

At the first 25 mile checkpoint I was already at 49.5 (7.1 mpg ahead of the split from last time) and I had hopes of edging that up a few points. However the right turn west met a noticeable wind, which persisted the rest of the distance. The 50 mile checkpoint was reduced to 48.7, still 5.7 ahead, and now came the 7% grade.

I was hoping to blitz up it this time instead of dragging up like last time, but a big truck got in my way at the start and seemed to be keeping a decent speed so I stayed behind it. However it was losing speed going up the hill, I cruised by it in the first passing lane, then it picked up again and followed a few feet behind me. Meanwhile the honda was losing speed as the steepness kept increasing. I tossed up my hands like, where am I going to go, off the cliff? Fortunately there was another passing lane and the truck scooted by.

Meanwhile I was keeping watch on the temperature gauge. It went up to 208.4, then I was relieved as it bounced down to 206.6 while I was still going up. The grade lessened, and the temp came back to 199, just about right I think. The ave mpg had reduced to 44.2 at the peak, but picked up again going down and reached 48.x (3?) at the 75 mile split between trucks. Today was the day for trucks, as they were either a ways in front of me putting on brakes for no reason, or scooting up behind me and refusing to pass. Somehow I managed to persist, and clicked the magic 50 at 105 miles woohoo!

Meanwhile, another truck kept motoring along about 200 yards behind me. It would crawl up the hills, then tear down them right behind me as I was trying to make the most of my coasting. I tried to let it pass a few times but it wouldn't. The ave went below 49 and then came back up, the last 75 miles being through hills. I took it really easy the last 10 miles, managed to get above 50 again, then clicked over on 51 in the last quarter mile, a new record! The round trip average was 49.65 mpg.

My next goal is 55 mpg, but that will take more aero mods to approach.