Justaturbo95

iTrader: (2)

Working out the bugs to convert an existing MS and have a question. Where does the 5v ref for the TPS connect?

Joe Perez

iTrader: (8)

If this is a standalone, the +5 TPS Vref connects to the green / white wire at position 2K of the ECU, which supplies power to the TPS and the EGR position sensor. If this is a parallel install, do not connect Vref to anything.

Justaturbo95

iTrader: (2)

It is stand alone. So will go to 2K. Would you happen to know the TPS ground connection location?
Thanks for the info. So ready to get this thing on and running.

Joe Perez

iTrader: (8)

Below are the complete ECU wiring diagrams for the '94-'95 Miata.

The primary grounds are the heavy black wires at positions 2A and 2B. The black / blue wire at 2D is not a ground per se, however it must be connected to ground in order for the CLT and TPS sensors to work, so connect to to a ground pin on the MS as well.

Justaturbo95

iTrader: (2)

Good info, according to info I found, grd was 2C & 2D. So I have some corrections to make. I had seen these diagrams noted and should have pulled them up. Now they are printed so I shall go to town fixing. Thanks

Joe Perez

iTrader: (8)

2C is a ground, it's just not a good one to use for our purposes. It's a relatively light gauge wire that in factory trim serves as the shield ground for the O2 sensor and I believe is also a general analog ground. But we want to use the big heavy ones at 2A and 2B.

2D is a funny one. As you can see, the TPS, EGR position sensor, CLT sensor, MAF sensor, and O2 sensor element all use this wire as their ground, however it does not actually go to ground- at least not directly. It goes into the ECU, and then it goes through the ECU to ground. So with the ECU removed, this wire is now floating, and it must be connected to ground in order for those sensors to work.

So leave the connections you've already made to 2C and 2D in place, but add connections to the MS's ground plane for 2A and 2B with heavy wire.

Justaturbo95

iTrader: (2)

I was following your thought path and did just that, tied them together. Today I hope to put in the car and fire it. Setting up an old laptop for tuning and must figure out how to transfer the 1.6m megatune-extra file with a 3..5 floppy. Network card shipping today I hope. uggh.

Joe Perez

iTrader: (8)

Assuming Windows XP SP2 or later, right-click on file and select "Send to" -> "Compressed (zipped) Folder."

On the laptop end, you'll need PKZIP.exe (or Winzip, etc) to open archive, assuming it's running an earlier OS w/o integrated ZIPping.

Justaturbo95

iTrader: (2)

Thanks for the suggestion. Both machines are dated. Windows 2000 desktop & win95 on the laptop. Winzip only lowered to 1.58. was going to hyperterminal across but am missing my null modem adapter. Debating to make one or go buy yet another null modem.