IROCBOY

I have recently installed a tko 600 in my 1990 iroc. It has the 7730 ECM and I have tunerpro for it. The vendor for the transmission sold me a kit that utilizes the “ford” style vss from the passenger side of the transmission. I know it produces way more pulses per mile than the 4000 that the ECM is accustomed to. Is it possible to scale the information in tunerpro? Or should I splice in a Dakota digital box between the vss and the ECM? I’m sure this has been done a thousand times. I’m just wondering how everyone else does it. Thanks for the info in advance.


-Greg

RBob

iTrader: (1)

It may be easiest to use the SGI-5 box.

In $8D there are two areas to scale the VSS input. There is a set of hardware dividers that can be changed. These affect the pulse streams to the speedometer and cruise.

It depends upon the VSS PPM as to whether it will work correctly or not.

Then for the ECMs internal MPH calculation there is a divisor for it. More (good) info in this thread:

https://www.thirdgen.org/forums/diy-...-40-tooth.html

RBob.

MrWillys

As long as it is a sine wave (AC) the value can be modified.

MaxpowerTA

Yes ( i did it on my own TKO conversion) you can do it for the vss input to the computer which allows you to tweak it so the speed that shows in your datalog will be correct and the speed related functions in the ECU work correctly . You cannot however ues those parameters to calibrate the speedo. for that you need the SGI-5 box.

MrWillys

I even have an Excel file where if I have your tire height and rear gear it will produce a value for using the 4L60E where it measures rotations of the shaft.

RBob

iTrader: (1)

Does it handle the speedometer and cruise control VSS pulse streams? Otherwise the SGI-5 box is the way to go. Even at that, you are the only one mentioning the 4L60E trans VSS.

And if you have such a great SS, why aren't you posting it? A taker, not so much a giver.... (?)

RBob.

MrWillys

If you'll provide me with your rear gear ratio and tire size i'd be more than happy to provide you with the proper VSS value running the 4L60E with a 1227730? At no cost of course.

MGB

Reference to thread #2 - Question is, how do you go about performing this calc in the ecm? New to tuning, did some changes to flags to remove vats and egr that's it. Therefore not exactly sure how to do this.

My engine parameters are - 1991Camaro 3.1 v6 (in a 1973 MGB), T5 tranny, 1227730 AZTY ecm, $88 mask, Autometer speedo, 2 wire sine wave VSS, no cruise.
Use Tuner Pro RT program.

Presently I have the output (Hi) from the VSS going to the Speedo and to ecm (B10). The output (Lo) from the VSS going to the ecm (B9). Speedo works fine after calibrating it. Data logging revealed the ecm records double what the speedo reading is. The ecm output (B11) not used.

RBob

iTrader: (1)

This parameter:

RBob.

MGB

RBob,

Have to hold my head in shame. Searched and studied how to implement the code you sent me, but with no success. Programming, I am not very good at.
Are you up to giving some guidance, direction on how this is done?
THANKS IN ADVANCE IF YOU ARE WILLING

RBob

iTrader: (1)

You can add the parameter to the XDF file or edit the BIN directly in hex. Quickest is to edit it in the TunerPro hex editor. It is at address 0x51 for 2 bytes. Should see the values 0x07 0x31, change it to 0x0E 0x52. Commit the changes then fake change an XDF parameter to force a checksum calculation. See if that does the trick.

RBob.

MGB

RBob,
Thank you for the info. I was able to change the value for the road speed constant.
Next step is to road test, data log to see how it performs.
May take some time, rain in the forecast (car stays in when foul weather). Keep you posted of the results. Thanks again for the help, well appreciated.

MGB

MGB

RBob,

Was able to test run with the following results:
With the changes you gave me, the data logging returned 4X the input. The PPM for the road constant speed went from 4004.78 to 2011.13. Looks like have to go the other way.
I was able to go back into TunerPro RT and change the results of the road constant speed to read 8714.89 PPM. Accomplished this by double clicking on the item in parameters summary. This brought up a tab with a scroll bar. Moved it until I got the 8714.89 reading (close as I could get to 8000). Saved this, burned, installed and tested. Results was within 6 MPH between speedo and data logging. I can live with this. Thank you for all your help.

FYI:
Road Speed Constant at location 51, 52 ( Hex Editor)
Hex - 0X07, 0X31 PPM - 4004.78 (What I started with) (reading 2X on data log)
Hex - 0X0E, 0X52 PPM - 20111.13 (With info you gave me) (reading 4X on data log)
Hex - 0X03, 0X4E PPM - 8714.89 (Final input) (reading +6 MPH on data log)

RBob

iTrader: (1)

You should be able to tweak the multiplier parameter for better accuracy.

RBob.