After several months of jumping through different tunes, tuners and solutions, we finally have applied a Ford Racing fix that they have come up with to address the Idle issues of the Coyote swap that many are seeing. After doing the following, the BTC project is running the stock Ford Racing tune and the drivability is stock as can be and perfect. All idle issues have been resolved and the car just ‘works’ now!
Basically the fix consists of taking a OSS signal from your transmission, converting the signal using a Speed Dial and sending it to the main PCM.
I have attached a work sheet that shows you the proper wiring and parts needed for the ‘fix’.
We had to run an additional 2 wires from under the dash out through the firewall and to the PCM we have mounted under the passenger side fender. We put the speed cal up under the gauge cluster. We already had wires under the dash going to the OSS on the TKO-500. Their worksheet specs out which OSS units to use, our TKO had the correct sending unit so we did not have to replace. The OSS was going to the Autometer electronic speedometer and still is but a bit differently. Originally one side of the OSS was going to ground to make the speedo work but the diagram needs the negative side going to a pin on the PCM.
How we have it Wired…
- One side of the OSS off the tranny going to the green wire on the Speed Dial. We also tapped this same wire and have that OSS signal going to the Speedo and you just calibrate it independently, do not count on the speed dial other side to give you correct ratio.
- White Wire on the Speed Dial going to T-14 on the PCM
- Other side of OSS on the tranny going to T-38 on the PCM
- Red Wire on Speed Dial going to Ignition ACC.
- Black Wire on Speed Dial going to body ground.
- Set DIP switches on Speed Dial to 1-1-1
What you need
- Ford Racing Speed Dial
- 2 Pin connectors (contact Ford Racing to acquire them) to solder to the new wires and plug into the 50 pin PCM plug (it is labeled as such)
When inserting the Pins into the PCM plug, first remove the white cap lock off the connector, just pry gently and it pops out of position (See picture above). Use patience putting them in and when you solder them, make sure the thickness and profile are the same as the 18 gauge wire so they will insert properly. We used a file to file down the solder where it was high in places.
Crank and boom!… It worked perfect for us and Im sure it will work perfect for you.