Swap from AWD to 4X4 two speed TC

[mikez71]

Personally, I would try the stock map first to get a baseline feel.
Not that the factory tune is necessarily best, but it's a known quality that shouldn't cause any issues.

In my head, the flat schedule and lowered RPM's maybe designed to keep torque output steady and controllable?
Or the lowered RPM's might be to protect the transfer case? (or 4low doesn't even use Pattern B WOT schedule?) idk just a guess

Test them both out an let us know! (I can't test mine, I still have a different ratio's front and rear at the moment.. )

 

[SpareParts]

Personally, I would try the stock map first to get a baseline feel.
Not that the factory tune is necessarily best, but it's a known quality that shouldn't cause any issues.

In my head, the flat schedule and lowered RPM's maybe designed to keep torque output steady and controllable?
Or the lowered RPM's might be to protect the transfer case? (or 4low doesn't even use Pattern B WOT schedule?) idk just a guess

Test them both out an let us know! (I can't test mine, I still have a different ratio's front and rear at the moment.. )

It seems most people are ok with the way it shifts after swapping it. I can live with it if i have to, but i think it could be better.
I don't mind losing tow/haul mode if it can be made to work.
I don't think i have ever used tow/haul mode actually. So using that as a sudo 4Lo mode would work great for me.

 

[SpareParts]

Here is a file i got that might have 4Lo someone sent me but it is a Denali so probably not.

 

[mikez71]

In the '09 denali file, all WOT speeds are near identical.
All the 4 LOW's I have seen, have pattern B like the file I posted. (adjusted for gear ratio and put into Pattern A instead)

But I am wondering if there is another map...
This 08 Hummer H2 file I'm looking at does not have the same Pattern B..
Same WOT shift speeds as other maps, so it's impossible to use Pattern B for 4low..

The 4LOW map shifts out of first at 2.5mph.. so that doesn't seem right either..

 

[SpareParts]

For some reason your test tune you just did not register with me. Guess im a slight retard!
Anyway ill go load that and we shall see what happens.

 

[mikez71]

Well I COULD BE WRONG about Pattern B being used..
Looking at a Hummer H2 tune, pattern B is not straight lines..

Other possibility, is it uses normal map but 4LOW WOT shift speeds to shift early? (not only at WOT? HPTuner's labels aren't always right)
But again it would be shifting out of first by 2-3 mph, which doesn't seem right..
Maybe only using WOT 4LOW shift RPM's with normal map?

If you test it out, I guess we'll find out.. !
But I'm now wondering if the Pattern B with straight lines is a just an unused placeholder..

I will go log my truck and see if it says pattern B when engaging 4LO..

 

[mikez71]

DON'T RUN THAT FILE! (I doubt it will cause problems but... )

Well this is embarassing..
When I put it into 4LOW, the 'trans shift mode' showed "MUMD"

Unless that's some error because my front driveshaft is removed, but I don't think so..
With my front shaft out, I may try and log shift speeds to see if it matches anything..
Sorry about my ASSumption.. That is the only map that made sense to me based on WOT speeds....

I have sent a message to RPMExtreme to see what he says..
Possible that hptuners has not uncovered the map? I have sent a support ticket, we'll see what happens..

 

[SpareParts]

So i just got done running it!
If i leave it is drive 2H and put it into tow/haul mode im pretty sure there is a difference.
If i put it into 4Lo with tow/haul mode i can not feel a difference between tow/haul and normal drive.

 

[SpareParts]

Here is one from a 2009 someone just shared that looks like a 4X4.

 

[mikez71]

So i just got done running it!
If i leave it is drive 2H and put it into tow/haul mode im pretty sure there is a difference.
If i put it into 4Lo with tow/haul mode i can not feel a difference between tow/haul and normal drive.

Ha, too late guinea pig! (I'm just happy nothing broke on you! Shouldn't be any problem, just might not be any improvement..)
Does it happen to shift any smoother?
Maybe because you have more torque in 4LO, you can't feel the difference much down low..

Mid/upper throttles should feel different...(not necessarily smoother now that I'm wondering what shift map gets used...)
I think of it like this, normal map/2HI, the WOT shift speed puts you around redline.. normal map/4LO, you're not able to wind it out to 9000rpms..
Unless the 4LOW WOT shift rpm forces you to shift at 3000rpms, WOT or not.. (because 60% throttle position speeds are still too fast for low gear)

That 09 Silverado file shifts out of 1st gear a bit sooner, but the other gears look similar at WOT..
I swear some of these maps are never used, maybe development/testing?

Here's a tidbit about the manual mode shifting differences between '07-'09 and '10+, and 6.0 vs 5.3 & 6.2.
(Basically has to do with coming to a stop / taking off from a stop, and gear selection)
A little repetitive.. Might just start around the 3:40 mark..

 

[SpareParts]

Tried copying that 09 Silverado pattern B over to my pattern A. No real change.

He kinda describes it in that video.
With very light throttle at about 1800 rpm it will shift from 1-2 and about the same for 3-4. The shift is very fast and with it being so fast it jerks a little because the engine is still at 1800 rpm and the trans clutches are locking back up immediately.
3-4 feels a lot better as well as 5-6.
I know for sure mine uses pattern A for tow/haul mode. I could be wrong, but it sure seems that can be modified somehow as it is just programming and not a mechanical thing.

 

[mikez71]

Apparently MUMD (manual up manual down) is grouped with TUTD... I may have never driven in 4LOW fast enough to expect a shift? (google search)

 

[mikez71]

hpt tuners tells me the 4wd tables are correct. I guess it uses the 4wd WOT tables even at part throttle? My truck is set to 3000rpm 1-2 and 5000 rpm for 2-3 and 3-4. Guess it downshifts 2-1 a little over 2mph. They told me there are no other shift tables, and my tutd section doesn't have shift speeds, so it must go by 4wd wot tables..

 

[SpareParts]

I don't remember where i left off once it was discovered 4WD mode was not activated by the ECU.

 

[mikez71]

I feel like manual mode is not much of a compromise, since most likely you should be doing slow speed stuff in 4LO anyhow..

 

[randeez]

is the speed sensor in the tail of the transfer case?

 

[SpareParts]

There is no VSS at all.