T-56 magnum cruise control speedometer assistance

[jolambright]

Greetings,
I tried searching the forums for this but got no result. So if there is a thread regarding this then I apologize and please show me where. I have a 2007 Mustang gt swapped with a 2012 Mustang gt that had a T-56 magnum put into it. Everything was swapped, the pcm, wires, dash cluster and instrumentation. My original 2007 mustang had 3.31 gears as did the 2012. I have the wide ratio T-56 so the 5th and 6th gears are .74 and .50.

Because the transmission was never put into the pcm the cruise control never worked. I purchased an SCT tuner from americanmuscle and bama gave me a stock performance tune which works well. I asked them if they have a tune for the T-56 magnum and they said they did. However when I put the tune on the speedometer was all way wrong. I would be going 10mph and it would say I was doing 40. I would go 30 and it would say I was doing around 90.

I called them several times and they sent me different tunes trying to get it fixed and told me how to manually input the rear axle ratio and revs/mile with the tires to try and get it to work but no matter what I changed on the tune the speedometer did the exact same as was I stated before and it never changed at all. My tire size is 255/45/18 for all four.

Besides getting a custom tune to get this fixed is there anyway that I can fix it with the BAMA tune. Any help is greatly appreciated

Thank you.

 

[stkjock]

Does the error on the speedometer reading change when you adjust the parameters or does it stay the same? IOW - If you change the axle ratio does the speedo go from reading 40 to reading 50?

 

[jolambright]

The speedometer stays the same no matter what I adjust the rear axle to or the revs/mile. Thanks for replying btw.

 

[CPRsm]

Do you have a control box to convert the pulse from the T56 to what the ecu can read?

 

[JeffS197]

not sure if you have the same sct options as me, but revs/mile also needs to be set to accommodate your wheel size. maybe it has some wacko value in it that is throwing off your readings. just a thought..

 

[jolambright]

Are you referring to the box that takes the T-56 to convert the 3/2 wire process to the pcm? If that is what you mean then yes the kit for the transmission came with that.

 

[stkjock]

The speedometer stays the same no matter what I adjust the rear axle to or the revs/mile. Thanks for replying btw.

IMO - then it's not the tune that is the issue.

IDK the swap well enough to say what it is, but must me a mechanical thing IMO

 

[jolambright]

Yes I have the converter box that changes the 3/2 wire to go make it work with the 2011+ pcm. It came with the kit for the transmission from jpc. As far as the revs/mile adjustment yes I did that. My tires are 255/45/18 and upon looking it up online I changed it from 750 to 775 and still no difference.

 

[REDS197]

Call the number on the box. They will have you set the correct values for your car.

You set it for 50 and then they calculate the difference and tell you the exact settings.
I used GPS on my phone.

 

[jolambright]

You wouldn't happen to have the number on the box would you? Just if you know what it is or have called it so I don't have to get under my car to look at the box lol.

 

[REDS197]

I no longer have the car.

 

[REDS197]

http://www.abbott-tach.com/products.htm

you will have to open box to adjust anyway.

 

[jolambright]

Thanks, appreciate all the help everyone.

 

[cyclerick]

It could be the cable/plug going into the tranny speed sensor is not plugged in all the way or is faulty. I had a similar issue with mine and finally replaced the cable/plug and fixed the problem.

 

[frank s]

If all else fails, and you don't mind the discrepancy between miles traveled and the odometer reading (which I imagine depends on the same connections as the MPH), you might try a "head up" speedometer display.

I bought one from Beanworthy on Amazon.com. It's not the least expensive choice, a little lazy on quick speed changes, but otherwise is good: easier to read than the obscure dial on the dashboard, and isn't cluttered with other stuff that is likely to impede the simple understanding-at-a-glance of velocity.

It's been dead reliable for six months now, and eventually I will work up courage to plumb its 5-volt requirement into a switched 12-volt circuit; as it is, I have to unplug the cigar-lighter thing before bedding it down for the night.