Programming a T43 to work in an offroad buggy with 39" tires

[whypave]

I have a L92 thats stroked to 427ci from a 2007 escalade or denali and then its maded to a 6l80e trans. this is in an offroad buggy built for offroad racing and rockcrawling.

I need to program the transmission so that it shifts at higher rpms. currently (due to the tire size being way off I assume) the trans shifts from one gear to the next at very low rpm even at WOT.

I'm using a mast motorsports ECM but it has a cable to send all the necessary data to the T43 so it will shift.

I have EFI live 7.5 and 8.0 on the CD/hardware I purchased from Blackbear Performance and I'm not sure which version to use since 8.0 almost seems like incomplete software currently but perhaps it needs an update. I purchased the software in February and the license card has a Jan 26th date.

Any help in how to accomplish this would be very much appreciated. I am a total newbie with EFI live other than watching Justin Gadberry at Black Bear tune my 8.1L Suburban. I'm in CT and he's in VA so I'd like to be able to tune the transmission (and my Suburban for that matter) with the software.

Currently I'm going through the scanning tutorial provided with the software.

Thank You

[Ira]

For the moment, use V7.5 for scan and tune. Use V8.0 for upgrading and configuration of the handheld.

Ira

[ScarabEpic22]

Also, download the latest V7.5 and V8 software from the www.efilive.com homepage. Lots of new updates in the latest stuff.

[joecar]

Post your T43 file... people will ask: what axle ratio and transfer case ratio do you have...?

[gmh308]

in the T43 cal there is a speedo section. H0101, 102, 103, 136. PLus a speedo calculator.

Have a shot at getting these lined up with your diff and tyres.

[whypave]

My axles are 4.56:1 and the transfer case is either 1:1(probably obvious in hi range) or 3:1. I'm not too concerned about shifting gears when I am in low range, eventually I'd like to have some type of manual control over doing say a 1-2 shift but for now first gear is fine.

In high range is where I'm really concerned about getting the trans shifting right. I will post the T43 tune file once I pickup the buggy today and get efilive hooked up.

I have 7.5 off the CD and currently with web updates I am at 7.5.6 update 110. I will check to see if there is something even more recent.

Thanks to everyone for the responses so far.

[joecar]

Updates see here (http://www.efilive.com/index.php?option=com_content&view=article&id=48&Itemid=133).

V7.5.6.112 (scantool/tunetool)
V8.1.2.92 (2.6.33 for V2).

[whypave]

I downloaded the latest 112 update and I have not forgotten about this thread. I was out pre-running for the May 7th race this past weekend and the transmission up shifts really early around 2k rpm. also it does not downshift when you decelerate into a turn which then means it isn't in the right gear to punch it going through the turn and out.

Unfortunately I'm on a business trip right now so I can't post the stock tune or start to figure out how to adjust the shift points. When I get home Thursday I hope to post up more information and get advice from the experts because I really need the transmission shifting better before this race.

Thanks!

[swingtan]

I'm thinking out loud a little here...

Following on from GMH308,

In the T43 ( like most ) there are tables to set


the number of speed sensor pulses per KM / Mile {H0101}
the number of speed sensor pulses per revolution { H0102}
Final Drive Ratio {H0103}
Tire revolutions per KM /Mile {H0104}


Depending on the original vehicle, ( and working in metric.... ) these setting could be...


{H0101}: 49258
{H0102}: 36
{H0103}: 2.92
{H0104}: 478.0


This would be for a stock sedan with 19" wheels. The thing is that the figure for {H0104} appears to be a factor of 10 out on what it should be ( it should be 4780 ). Working backward through the figures shows {H0101} is also a factor of 10 out, so at least it's consistent.

In theory, {H0102} should net need to change, so you would want to look at the other three. The easiest would be {H0103}, which should be set to 4.53, but would only be correct for high range. In low the TCM will not know you have a 13.59:1 final drive ratio.

The next thing is that the 39" tires have a rolling diameter of maybe 900mm. This would give a Rev/KM value of 1111. This is what {H0104} should be. Then calculating back for {H0101} you get 181200.

So to allow the TCM to know what is going on ( in Hi range ) the values should be something like...


{H0101}: 181200
{H0102}: 36
{H0103}: 4.53
{H0104}: 1111


The only thing that doesn't make sense ATM is that with your current set up, assuming stock values for the speedo, it would shift late.....

So I wonder if the TCM is getting confused and up-shifting early because the RPM / speed correlation is way off. Maybe the TCM is up-shifting because it sees high RPM, but is reading a VSS that is much lower than it thinks it should be.

An idea to see what is happening would be to log the TCM parameters. There is a chance that it's getting bad data as well. for a start, I'd log the following from the T43....


Engine RPM
VSS
ACCEP


this would at least let you know what the TCM thinks is occurring.

Simon.

[VTcivil]

I'm the original poster's co-driver. I figured I would post a couple pics to help stimulate the discussion. I know Dave is out of town on business and will be more active on the thread here shortly when he is back working the buggy i think tomorrow.

[gmh308]

I'm the original poster's co-driver. I figured I would post a couple pics to help stimulate the discussion. I know Dave is out of town on business and will be more active on the thread here shortly when he is back working the buggy i think tomorrow.

yes those tires are rather talll! :)

I get different numbers to Swingtan. Dont know why: calculator says >

H0101 - 52750 per km / 84892 per mile
H0102 - 36 of course is same
H0103 - 4.56 of course is same
H0104 - 321 tire revs per km / 517 tire revs per mile.

These numbers if duplicated in the ECM should give you a 4000ppm speedo output signal. (OS & cal permitting.)

I doubled check the above numbers via regular math and they line up ok. :)

[swingtan]

The big problem is that you can't "guess" the circumference of these tires due to the size and probably running pressures. During racing, they will probably be inflated to a lower pressure than a normal car would to allow the tire to deform and add traction ( like drag slicks ) so the actual rolling circumference will be less once load is placed on them.

I should test the relationship between {H0101} and {H0104} to see if the individual numbers are critical, or if the relationship between them is what counts. I don't have an auto to play with ATM though. My figures were really just an example.....

To get the "real" rolling circumference, mark the tire with liquid soap or grease ( or anything that leaves a mark ) and roll the buggy forward so you get 2 marks on the ground. Then measure the distance.

Simon

[A6sportsracer]

I suggest setting it up for tap up/down shifting like the corvette, You may be able to install a vette wheel or column to use the tap up/down switches, if you use your own switch(s) you will need to wire it through an original corvette switch because of the three resistors in the switch.

[whypave]

Sorry I didn't post back up sooner. Our race was last Friday so last week was a lot of long days and nights getting the buggy put together enough to race.

On Tuesday of last week I took the buggy to Chuck at Corvettes of Westchester and we did some tuning of the T43 in my 6l80. it shifts much better now and actually downshifts which was a huge improvement in the race. the shifts are fairly slow and we need some more tweaking but we are working on it. the big improvement came from both setting up the right r&p ratio as well as tire size but then Chuck changed a bunch of other shift points and turned of torque management etc.

I will try to keep this thread updated as to my progress in case anyone is interested or someone comes along in the future trying to put one of these trans into a non GM can bus vehicle.

I must say now that I've learned to use EFI live a bit more its pretty damn cool to work with. the main problem i had originally is that the obd2 port on my Mast harness is not currently communicating with the trans. Chuck had to use a bench harness with an e38 hooked to it to get efi live to see the T43 controller. so we had to do a bit of extra work each tune to unplug the harness from the car to the trans and plug in the bench setup then reverse the process to go testing.

Unfortunately my 427 L92 has enoug power it snapped an axle shaft from street driving and the rear spool. we found that out the hardway when we went to qualify for start position last Thursday.

[Chuck CoW]

CHUCK CoW can tune ANYTHING with an A6!!!

WATCH and SEE BELOW!

http://www.youtube.com/watch?v=rP2jIHY9R30&feature=player_embedded#!

Chuck CoW

[whypave]

Thanks for posting the video Chuck. once I get a few bugs sorted out with the buggy I want to come back and try and setup tap shifting. I need to get my obdII port live so we can talk to the transmission without your bench programming box.