Miata Turbo Forum - Boost cars, acquire cats. - How to wire an analog TPS to MS in a '90-'93 car.

- MEGAsquirt (https://www.miataturbo.net/megasquirt-18/)

- - How to wire an analog TPS to MS in a '90-'93 car. (https://www.miataturbo.net/megasquirt-18/how-wire-analog-tps-ms-90-93-car-36271/)

Let me double check the wiring diagrams.

Try this:

Code:

TPS              Function        Harness

GRN/BLK        TPS SIG        GRN/WHT

BLK/RED        GROUND         BLK/GRN

GRN/RED          5vref             RED

I had you reverse the sig and ground.

tried this with my MS3x and had no luck when Calibrating. Ive checked the wiring on numerous occasions and everythings right. sigh.

Just as note on this topic, I found the automatic variable tps on an escort GT this weekend in the junkyard. Same part number as the miata even though the GT was a 1.8, it still had the 1.6 throttle body and not the 1.8 style. I haven't seen that option documented anywhere yet.

interesting.

but i dunno what the deal is with your wiring. You can check it the old fashion way to make sure you have the proper singals. The MSPNP2 docs say that's all you need to do for the tps: wire it in.

Quote:

The easiest way to check a TPS is to unplug it and put an ohmmeter on its pins. Observe the resistance as the throttle opens and closes. Each pair of pins will behave differently:

The resistance between the VREF and ground pins will remain constant.
The resistance between the ground and signal pins will be low with the throttle closed and high with the throttle wide open.
The resistance between the VREF and signal pins will be high with the throttle closed and low with the throttle wide open.

Ive tried 3 different vTPS' from auto TBs. They all work fine off the car and the OHMs check good. My values in TS are all over the place. Possible bad throttle body somehow?

Link to decent VTPS option for 90-93s:

https://www.miataturbo.net/megasquir...tps4185-75375/

Back from the dead!

I've been struggling with the TPS signal on Oregonmon's VVT swapped 1990. After following the VVT swap thread's instructions:

https://www.miataturbo.net/engine-pe...athread-80469/

I found the TPS wiring instructions for a 1.6 lacking. So I googled "90-93 miata vtps wiring", and this thread was the first non-m.net result. Followed these instructions to the T, as I was using an NB TPS:

Quote:

Originally Posted by Joe Perez (Post 421081)

For an NB TPS, the green / red wire goes to the green / white wire of the car, the green / black wire goes to the red wire of the car, and the black / red wire of the TPS goes to the black / green wire of the car.

But later on Braineack's instructions say that the 5v ref and signal are swapped from Joe's description

Quote:

Originally Posted by Braineack (Post 930521)

black/green to black/green

tps green/red to harness red

tps red/black to harness green/white

Even later still, Braineack confirms this wiring:

Quote:

Originally Posted by Braineack (Post 940132)

Try this:

Code:

TPS              Function        Harness

GRN/BLK        TPS SIG        GRN/WHT

BLK/RED        GROUND         BLK/GRN

GRN/RED          5vref             RED

I had you reverse the sig and ground.

My original wiring was complete junk, resulting in random close throttle values from -10%-10%, and barely touching the throttle would result in it going upwards of 25% negative, before finally going positive around 50% throttle. Obviously this made closed loop idle and accel enrichments nearly impossible to tune.

If you're having these same issues, try following Braineack's wiring, it's correct, Joe (for possibly the first time every) is wrong.

For the life of me i cannot find a pigtail for the vtps. Can anyone help me with this?

So is there a way to avoid all the wiring, by just buying another style of tps and making that work?

I don't mean no wiring at all but like.... not messing with my ecu. I'm a baby about that

Quote:

Originally Posted by Jacob Ray (Post 1320492)

I don't mean no wiring at all but like.... not messing with my ecu. I'm a baby about that

why would you have to mess with the ECU?

Quote:

Originally Posted by JohnnyMorto (Post 1211206)

For the life of me i cannot find a pigtail for the vtps. Can anyone help me with this?

which "the" vTPS?

In FM's 1.8 swap guide, it says this:

"The 1.8 throttle position sensor (TPS) won’t talk to the 1.6 ECU, so you must retain the 1.6 TPS (if you retain the stock ECU)."

Is that simply assuming if you just bolt NB TPS on and don't rewire as outlined here?

meaning this upgrade is pointless unless you have an aftermarket ECU that knows what to do with the signal.

Since this thread is back from the dead - I'll tack on a question I've been chasing. I just switched to a 4-Wire Auto TPS on my 1.6 and followed the wiring diagrams you all so graciously put out there for us! However, I have voltage creep on the sensor now. It will bottom out when I come off the throttle, and that is where I calibrated my TPS lower limit. However, if I let it sit there for a few minutes, it's voltage creeps up and the % showing in the TPS will creep up as well. After about 5 minutes it will be as high as 35 or 40%. Any ideas on how to diagnose/fix?

FWIW: I had it on a bosch variable TPS without this issue, but that throttle body exploded at the track so I swapped in the whole assembly from an auto car. 1.6 racecar.