Altitude and hills = better mpg

[pete c]

Just got home from vacation in California. Borrowed a friend's Toyota motorhome for a trip to Tahoe and Yosemite.

These RVs with the 22RE 4 banger and auto generally get 15-17 mpg driven conservatively. The tank from Lee Vining to Mariposa involved crossing Tioga Pass, which is around 9500 ft, driving down into the valley and then up to Glacier Pt at about 7200 ft. I averaged 18.3 for this trip.

The owner, according to his logs had been typically getting 13-17 mpg. I was traveling with a heavier load, 4 people vs 2.

I suspect my better mileage came from being very patient on the climbs (1st gear for long stretches climbing the passes) and doing some minor hypermiling (coasting in neutral on long downhills that weren't too steep). Wouldn't dream of EOCing an auto, especially one with a house on its back. I believe holding first gear on the climbs was vital. The auto in this thing is a 4 speed with very wide ratios. On a steep climb it will pull first gear effortlessly at 25 mph with almost no throttle input, but, if you leave it in drive, it will shift to second and it pretty much falls flat on its face. It will however lug along with lots of throttle. I suspect that this much throttle at that low an rpm is not a happy place for it. So, I left her in first and let the little 22RE spin its heart out at about 23 mph or so. And made good use of turnouts for faster vehicles. The temp guage for this fantastic engine never budged from its normal position, just below 1/2. Not bad for a 4 banger dragging a house over a mountain.

The trip from Mariposa back to Watsonville, I came within a hair of cracking 20 mpg. I suspect this is due to the nice gradual loss of elevation from the Sierra foothills to the central valley. Much of this was spent at 50 mph barely into OD with almost no throttle. Wish I had a scanguage as I'll bet that damn thing was getting close to 30 mpg in this mode.

Is there any chance that this 1989 vintage engine uses DFCO? I suspect it doesn't. Next question is would installing a manual CO on an automatic tranny engine be wise? Would the auto keep the engine spinning during FCO or would it stall?

[Frank Lee]

I don't know, but you could have stopped in to say Hi to Craig Vetter!

[some_other_dave]

Originally Posted by pete c

Is there any chance that this 1989 vintage engine uses DFCO? I suspect it doesn't. Next question is would installing a manual CO on an automatic tranny engine be wise? Would the auto keep the engine spinning during FCO or would it stall?

My 1990 CRX had DFCO over about 2500 RPM. Heck, in the early 1970s some of the earliest fuel-injected cars (aircooled VWs using analog electronics to control the injectors!) had DFCO. So it is entirely possible that a 1989 Toyota had it.

An automatic transmission can keep spinning an engine on overrun. Some seem to decouple from the engine (or come close to it) when coasting, but others still keep the revs up.

I am not familiar enough with Toyota drivetrains to say for certain on either count.

-soD

[SentraSE-R]

No, a 1989 engine almost certainly doesn't have DFCO.

Since there's only a fluid coupling between the AT and your manually fuel-starved engine, I wouldn't depend on enough engine turning to lube the AT.

[pete c]

Yes, you are likely right. Just not enough of a gain in fuel savings to risk tranny health, especially on a tranny that's working as hard as that one. Eventually, I will find my dream toyota RV, a 22RE manual. Unfortunately, that drivetrain is quite rare. If I come across a 22RE with auto tranny issues, I'd consider buying it if it was cheap enough and convert it to a 5 speed.