'06 6speed tuning inconsistancies

[bballer182]

Anyone else having trouble with basically all of the tables' speeds for shifting and TCC control not matching even close to what the VSS reads? This makes tuning extremely hard because none of what is in the tables has anything to do with actual speeds. And not only that we can't even log (BBL or pass-thru) the VSS through the TCM, so we have no idea what speed the tcm thinks it's going.

Making changes by only a "unit" (which is what i'll call it) or 2 in reality is like a 3-6 mph change. I don't get it.

[bballer182]

Ross?.... anybody?.....

[GMPX]

We'll look at it after DSP is done.

[bballer182]

Cool

[THEFERMANATOR]

I've made quite a few changes in my LB7/LLY style TCM to shift points, and when making changes you have to remember that the TCM is calibrated for 4.10 gears with 29.56" tire. So you have to find a multiplier to use so you can convert the shift point that is shown in the graphs to an actual shift point in real life. For the ALLISON it is calibrated for 111903 pulses per mile when you go under the speedo calculator. Now go into your ECM and find the pulses per mile that it uses and write that number down(I dug up a stock file for 245's and it was 101808). Now take the 111903 for the TCM and divide it by the ECM's(in this case the 101808) and you now have a multiplier of roughly 1.099. Now whatever is shown in the chart multiply it by the 1.099 and you will get the rough shift point that it should take place at. Also remember though that the chart with numbers doesn't have decimals, but when you make changes to the graph it will make decimal changes without it showing up in the numbered chart.

[bballer182]

After about an hour of messing in the the Speedo stuff in the TCM, all of the shift point and tcc lockups match to real-world speeds and are no longer numbers without meaning.

(ALLY 6SPEED BTW) 5 speed is a different beast.

I changed H0103 to 3.73, inserted my real tire revs/mile (matching the ecm), then used the "shift point correction" calculator to get the new shift points. I did this by knowing my 5-6 part throttle up-shift is 60 mph (real world)and it was 51 (in the tune) at 30% tps. so i took the % difference and inserted that into the calculator to convert all of the bogus (stock) shift point to real world numbers. Then the last thing i did was drive it to see if it was right and it wasn't it was holding the 5-6 shift for and extra 4mph. so i took that % error and adjusted H0137 (Vehicle Speed Ratio), it was a shot in the dark because i had no idea what that table does and the description is kinda lame, but it worked non the less.

So now all my shift point match my speedometer!

[horsehaulin]

I know this is diggin this thread a little, but is there anyway to make the tables self correct once the real world gear is inserted?

[bballer182]

if u are asking what i think you are asking then, yes. just use the shift point correction calculator and instead of inserting mileages just use a percentage to correct all the tables.

[LBZoom]

I have a similar issue with mine, I just recently started messing with my tranny to any real extent. I changed the gearing in the table to 3.73, and changed the pulses per mile by the same percentage to match the change in gear ratio. I'm not sure if that was correct or not but I haven't had any issues so far. One thing though, similar to bballer's, my real world shift points are about 2mph more than my tables display at 20% throttle. I assume the RPM's are off a little too but I wasn't able to spend as much time as I wanted going over logs last night. I used the shift point calculator and made a 7.75% increase to essentially all the tables, bc I run a 285/75R16 tire, and my actual tire revs per mile is 640 and my speedo is GPS verified. I am happy with my actual shift points, but how can I change my tables to match and flash it into the truck with actually changing the real world shifts as a result. I need to keep my actual shift points but be able to modify the tables "so the TCM doesn't notice a difference" so to speak... Follow me? Thanks guys!

[LBZoom]

I think I got it straightened out, I just increased my shift points by 9.9%, same as multiplying by the 1.099 factor, and lowered my vehicle speed ratio by 9.9% and for some reason it worked...I won't question it lol. But I left the 4.10 gear ratio in and the pulses per mile was untouched as well.

[EagleBay]

Hi all. Old thread but was looking to solve why my shift tables didnt match real world speeds and thought I would post here as I couldn't really find anything else on the web
I have an 06 LBZ and with Allison 1000/A40 swapped in a Nissan Patrol with 4.1 diff ratio and 33" tyres.
Have made improvements to shifts by altering shift tables but it always annoyed me why real world speeds didn't match the tables but put up with it for years as it was shifting nicely anyway.

I experimented with altering diff/axle ratios and tyre sizes but made no change.

My 5-6 upshift at low throttle was set to 85kph but real world was 90kph. This is a 5.7% difference.
So I put axle and diff ratios back to stock 4.10/3.73 (to ensure inaccessible tables aren't referencing these figures) and reduced vehicle speed ratio by the above 5.7% and now my shifts are near bang on real world
I kept the tyre revs per km the same as the figure I entered into the ECM as this gives the vehicle speed PID accurate to GPS, I did this by inputting the measured diameter from the ground to the top of the tyre in the EFI live speedo calculator and using the calculated value. Keeping the TCM tune the same as the ECM tune makes sense to me even though I proved earlier changing this value in the A40 calibration didn't make any difference.

So if anyone reading this wants their real world speeds to match the shift tables, work out what the error is and alter the H0137 table by the same amount

My settings below


{H0102} Vehicle Speed Sensor Pulses per Revolution 40
{H0103} Final Drive Ratio 4.10
{H0105} ECM Pulses Per mile 4000 count/mile
{H0122} Axle Ratio 3.73
{H0136} Tire Revolutions Per kilometer 397 rev/km
{H0137} Vehicle Speed Ratio 248 rev/km
{H5061} Transfer Case Ratio 2.72 :1