Have any of you that have gone 165 to 730 just removed the VSS buffer entirely and ran a direct feed from the VSS to pin B10 of the 730 ECM? I understand what Mike's instructions say to do, but I am wondering how successful removing the buffer all together and running the VSS right into the 730 would be. Does the 730 have it's own buffer circuit on board, or? What about feeding the Speedometer if I do this? I haven't looked at the 165 VSS and Speedo system diagrams, but I am assuming that the 165 system uses that buffer to feed the speedo and the ECM with independent circuits.....

I have swapped to a T56 as well and have a 4th gen VSS feeding into a Dakota Digital box. That box has different outputs on it and I am wondering if that might make this a possibility if it is otherwise not possible......

TIA,
Matt

 

you have a couple options that deal with getting the ECM speed info. You can use the box and connect buffered data to C6 per Mike's instructions and remove the magnetic VSS checkmark in the PROM. In essence you are replace the old buffered line from the speedo. Or you can not use the box and connect the VSS directly to B9 and B10, and change the road speed constant to ~40000 in the PROM. When I converted to a T56 I experimented a little and those were the only paths that worked. Plugging the OUT from the box into B9 or B10 didn't work. I tried. It's just two different signals.

Bigger question: what are you planning to do about the speedo? I ran w/out one for a few months. I could never get the autometer electric one to to work, I guess I broke it while grafting it into another modified panel assy. I finnaly installed the JTR cable conversion kit. Wasn't that hard to do. Machining only cost me $80. And I can go between an auto or manual tranny at any time.....since I just plug my mechanical cable in.

 

Well I certainly do not want a cable driven speedo!!!!! (no offense) I have had plenty of cars with them and do not like them one bit. I am going to keep the factory speedo one way or another. It sounds to me like my only option is to keep the buffer and run the buffered input into the 730 and leave the speedo feed from the buffer circuit intact. Not a big deal really..... Just would have been nice to get rid of some more wiring and crap.

Would you (or anybody else) happen to know if this magnetic VSS checkmark (box, or whatever) is readily available in Tunercat as of right now? I skimmed through it and didn't see it......

TIA,
Matt

 

the magnetics VSS is in the constants section in the newer TDFs (tunercat). I forgot you had a GTA, which means electric speedo. You'll need to utilize the box in order to have both a correct speedo and ECM speed data if you have gears lower than 3.42 I think.

 

OK, well check this diagram out:

http://www.mnfbody.com/memberpages/m.../419058002.gif

Looking at that, the speedometer is expecting 4000 ppm and the ECM and Cruise Control are expecting 2000 ppm. Now, the 730 ECM, if I am understanding it correctly, has a place for a 4000 ppm output for the speedo and a 2000 ppm output for the Cruise Control, as well as a reception pin for a VSS signal that I would assume is 4000 ppm (different from the 165 that is looking for a 2000 ppm).

Now the Dakota Digital box has different outputs and one of them is for a 4000 ppm output. So it can cut the 40,000 ppm output of the 4th gen VSS down to 4000 ppm for me (still need calibrating obviously)...

Soooo...... I am thinking that I can move the output wire of the DD box to the 4000 ppm terminal of the DD box and run that wire into the B10 VSS input pin of the 730 ECM to get the 4000 ppm input to the 730 ECM. Then run the speedo feed wire that normally came from the buffer and run that into the 4000 ppm output pin of the 730 ( B11 ). Then run the Cruise Control wire that normally came from the buffer into the 2000 ppm output pin of the 730 ( C1 ).

So I am thinking that I would not need to change the VSS magnetic constant setting in the PROM or have a the buffer anymore......

This is all assuming that the 730 has some inherant buffer abilities...... (or is that really an issue with the speedo and cruise control worth worrying about.....)

Whatcha ya'll think????

TIA,
Matt

 

Well, I finally had some time to play with the car this weekend but I left the speedo stuff alone and just disabled the DTC 24 flag in the switch fields of the bin. The speedo works fine now so I probably won't mess with it until I have more free time on my hands...... Other tuning issues have my full attention at this point . I still like the idea of getting rid of some more wiring and components though ......