4 low transmission shift points?

[Glenn]

I am trying to delay the 1-2 shift at wot to 4000rpm. I have lowered the gov. pressure in table B4522 with no change. Also have raised thottle valve angle in table b4536 and changed the full throttle shift rpm in b4546 to 4000rpm. Any words of advice?

[Glenn]

Anybody? I am starting to think that the 1-2 upshift rpm cannot be adjusted.

[DoghouseDiesel]

What have you lowered the Gov pressure to?

Everything in the 1-3 shift points is 100% hydraulic pressure.

Can't say I've messed with the low range settings, but what are you trying to accomplish? Is this a sled pulling application?

[Glenn]

It is a sled puller. I have lowered gov press in the 4 low table to 0 psi from 0 shaft rpm all the way to 3500 rpm with no effect on the 1-2 shift. It did make the 2-3 shift non-existent.

[2007 5.9]

I have found the same to be true...a (0) value for gov pressure in low range, still had a 1-2 shift at previous rpm as a unchanged gov pressure table.

For my pull truck..I have resorted to manual shifting...

[DoghouseDiesel]

What are you doing with the TTVA angle?

If gov pressure overcomes the pressure applied on the back side of the shift valve, it's going to shift.

Have you increased the TTVA angle along with dropping the gov pressure? And, have you been logging the governor pressure and TTVA angle, both commanded and actual? If you have, post the logs.

Also, who's valve body is it? I'm assuming it's not stock, which means it probably has a shift kit or at least some spring work.

[Glenn]

I have raised the TTVA angle also with no change other then a firmer shift. It has a suncoast valvebody.
I will try to get some logs today and post them.

[DoghouseDiesel]

Okay, suncoast uses nothing more than a transgo shift kit. This changes a few springs, drills a few holes on the valve body and raises the line pressure.

You need to log commanded and actual governor pressures as well as TTVA commanded and actual.

This is the same thing I tell everyone that starts messin with this trans, you MUST understand the valve body and how it functions, especially if you have an aftermarket setup. With almost any of them youn can raise the shift points by simply adjust the TTVA stop, but this is only part throttle conditions. Everything else is regulated by governor pressure and if you're not logging it, you don't know what's going on.

First, do some research on your VB. You may be pissing up a rope depending on what actually got modified.

Regardless of what you tell this transmission to do, IT'S DUMB, it's completely hydraulic. If the pressures aren't where you expect them to be, you have to tune around the VB mods.

[Glenn]

That is what I dont understand. I realize what it takes to make a shift, If there is no gov pressure commanded it should never build enough pressure to overcome the line pressure. I have not logged it yet. But if the only table for 4low gov pressure is set to 0 across the board, where does the gov pressure come from?

[DoghouseDiesel]

Log it and see what it does. If it's stil showing pressure then there's more than likely a table such as a base duty cycle or the like that is still missing. Bottom line is its a solenoid, so there should be a base / max duty cycle map associated with it, kind of like FCA does.

[Glenn]

Log it and see what it does. If it's stil showing pressure then there's more than likely a table such as a base duty cycle or the like that is still missing. Bottom line is its a solenoid, so there should be a base / max duty cycle map associated with it, kind of like FCA does.

Do you know of a table I did not mention? Or is it missing?

[2007 5.9]

That makes sense that there is a min DC or pressure table...as stated above although I didn't log it, but a (0) value in all 4-low gov tables still encountered a shift schedule that resembled stock.