Torqshift upshift/rpm advice

[Invent1]

Our 08 Itasca 30B (9k miles) has developed a questionable trait: upshifting very late when first started (cold if you call 65F cold). Leaving our neighborhood, after sitting for a couple weeks, the motor stays in the lower gears even when rpm is over 2500 (with minimal acceleration on a flat road).

At other times, it does a very rapid, hard upshift like it has suddenly woke up.

This makes me wonder if it is not even getting into fifth gear because mpg has been consistent in the low 7’s (7.1, 7.3, with 7.5 for a high). This seems low because there is no Toad, our driving is on flat (usually FL) highways, outside temp is in the 60-90 range, and we average 60 to 65 on the highway. Plus very little metro driving.

Engine is the 6.8L Ford V-10. Tires are 95-psi front/85 rear. Toe-in good. Little to no generator use. Tow/Haul OFF. 19.5 tires. Battery has not been disconnected.

Can anyone advise:

1. Is the late shifting when ‘cold’ normal for the new Torqshift?
2. Is the occasional hard upshift normal for the new Torqshift?
3. What rpm is normal for this model at 60 mph in fifth gear? (Or where can I find the fifth gear and axle ratios - not in any of the manuals?)

 

[Invent1]

Our 08 Itasca 30B (9k miles) has developed a questionable trait: upshifting very late when first started (cold if you call 65F cold). Leaving our neighborhood, after sitting for a couple weeks, the motor stays in the lower gears even when rpm is over 2500 (with minimal acceleration on a flat road).

At other times, it does a very rapid, hard upshift like it has suddenly woke up.

This makes me wonder if it is not even getting into fifth gear because mpg has been consistent in the low 7’s (7.1, 7.3, with 7.5 for a high). This seems low because there is no Toad, our driving is on flat (usually FL) highways, outside temp is in the 60-90 range, and we average 60 to 65 on the highway. Plus very little metro driving.

Engine is the 6.8L Ford V-10. Tires are 95-psi front/85 rear. Toe-in good. Little to no generator use. Tow/Haul OFF. 19.5 tires. Battery has not been disconnected.

Can anyone advise:

1. Is the late shifting when ‘cold’ normal for the new Torqshift?
2. Is the occasional hard upshift normal for the new Torqshift?
3. What rpm is normal for this model at 60 mph in fifth gear? (Or where can I find the fifth gear and axle ratios - not in any of the manuals?)

 

[tderonne]

First the specs:

245/70R19.5 tire, 33" OD, 627 revs/mile
5.38 axle
.717 top gear ratio

Using the above gets you:
2428 RPM @ 60 MPH in top gear
3372 RPM @ 60 MPH one gear down

That said, you may not have 245 tires? The 18,000 pound GVWR chassis may use narrower tires?

Also don't assume your tach is correct. It's close, but don't try to use it to the last 50 RPM. (50 RPM at 2500 RPM is 2%, not too bad for any gauge)

As for the shifting. I'd expect the shift points to be the same over time, with maybe a little change for trans temp. But overall, there's one shift cal for all the same tire and axle combo, regardless of GVWR. Your smaller coach may really want a slightly different schedule than a 35' one, but they are the same.

If it's not doing what it's commanded to do, it ought to set a code. Being an '08, it might be worth a trip to the dealer to check all codes, and take a quick test drive.

 

[DeanLinAZ]

My experience and memory recalls that most of the automatic transmission vehicles that I have owned (cars & motorhomes) all were slow on the up-shift during the initial startup and drive-off from cold, even in Arizona. Just apply power easily when you first drive away.

Sounds normal to me.

 

[Fakrwee]

This may not apply to your situation but it's worth a shot. Electronic transmissions have a memory. They adjust to your way of driving.

Try disconnecting the battery for 10 or 15 minutes. Start up the MH like you usually do and start driving. Sometimes it changes shift points.

Good Luck
Tom

 

[tderonne]

The only thing that is learned is line pressure adjustment to keep shift times to preset times. Shift schedule doesn't change.

 

[Invent1]

Tim,

Thanks for the information. It's exactly what I need. And, yes, the tires are 245/70R19.5.

And your advice on gauges is dead-on too, I've designed several electronic gauges. +/- 2% or +/- 50 rpm would be very good for an automotive tach.

Just a point of curiosity,in the pre-electronic days I believe a mechanical rod that was connected to the throttle varied the shift point (i.e. upshifted at a higher rpm when your foot was in it) and the vacuum modulator made the upshift faster and harder when vacuum was low (again when your foot was in it).

When you said "The only thing that is learned is line pressure adjustment to keep shift times to preset times. Shift schedule doesn't change." Does that mean that the rpm vs throttle opening schedule remains the same for upshifts regardless of the "learning", and that "learning" only chnages the hardness/softness of the shift changes?

In any case, it appears that the trans is making it to fifth gear, and the 7.2 mpg on flat roads at 63 mph is something I'll have to live with.

Thanks again for the excellent info,

John

 

[tderonne]

<BLOCKQUOTE class="ip-ubbcode-quote"><div class="ip-ubbcode-quote-title">quote:</div><div class="ip-ubbcode-quote-content">Originally posted by Invent1:

When you said "The only thing that is learned is line pressure adjustment to keep shift times to preset times. Shift schedule doesn't change." Does that mean that the rpm vs throttle opening schedule remains the same for upshifts regardless of the "learning", and that "learning" only changes the hardness/softness of the shift changes?
John </div></BLOCKQUOTE>

Exactly. The base shift tables are all vehicle speed vs. throttle position. And the only thing that is learned is a small adjustment in the shift pressure (EPC in Ford speak, Electronic Pressure Control, and it's not just dependent on throttle, like in the old days, "calibratable beyond explanation" is the best I can describe it).