4-wire TPS for na bp mtx ?

[92lx_nu2me]

sorry, everyone, this has been covered, but the more I read the more confused I got.

I have a 92 LX with na BP and mtx. its a 3-wire switch-type TPS.

I want to install a WB o2 controller that can also datalog (see link below). It would be helpful to be able to datalog throttle plate angle, but this requires TPS with linear potentiometer, like the 4-wire atx TPS.

I can handle the wiring part (the output of the linear potentiometer won't go to the ecu, it'll go to the WB o2 controller for datalogging). What I don't know is whether the atx TPS is a direct swap to a mtx throttle body. Seems I have read that its not because one has a D-shaped throttle plate shaft and the other does not. Is this true? What about swapping the whole atx throttle body with 4-wire TPS for the existing mtx throttle body?

Seems I have also read that the GTX (BPT) also has a 4-wire TPS, but I don't know if that's a direct swap either, and where I could get one if it would fit.

The WB o2 I'm going to try is the JAW (its a DIY assembly)

https://www.14point7.com

Thanks in advence for your time.

[Lex]

The problem is that your ECU will expect the 3 wire output.

However the atx and mtx cars have the same intake manifold so TBs swap over. The tps itself I am not sure about.

[MATT91GT]

im not sure what it does, but i have one installed on my EGT and its a 5spd, got it and put it on expecting to finish my turbo that summer, then changed my plans. and just left it. i dont see any negative effects from it.

[Turpro]

The auot and manual tb are both the same but the tps and mounting is different. You cannot mount a 4 wire tps onto a manual tb and vice versa. You have to swap the whole tb.

[92lx_nu2me]

Turpro

Thank you. This is what I needed to know.

From the way I read the wiring diagrams, three of the four wires on the 4-wire TPS do the same function as the three wires of the 3-wire TPS. I'll have to look at the diagrams again to get the pins right. The fourth wire on the 4-wire TPS should be the potentiometer output I can use for datalogging through my WB 02 controller.

Thanks again !!

[jasoncsprotege]

actually the 4th wire on the tps is hooked to the air flow meter, and IIRC that wire is a 5 volt wire
Jason

[Mazda_Powered]

what Jason said. The 4 wire actually reads a 0-100% versus the 3 wire which is just open and closed from what i've heard.

i have an auto TB with a 4 wire tps i'll be using, also a 4 wire o2

JACK.

[323driver]

swap Throttle bodies and hook up 3 wires to your ECU (like you said) or swap for an auto ECU and splice in your WB. I have a manual with auto TB and ECU and no problems here.

[92lx_nu2me]

thanks, everyone, for your replies

i looked closely at the Factory Service Manual, and it seems like my idea is not going to work.

the 3-wire and 4-wire TPS have two wires in common:

B/BR wire goes to reference / ground
R/W wire goes to pin 1N on the mtx ecu and to pin 1T on the atx ecu
this is the idle switch. 0v accelerator released and 5v accelerator depressed.

LG/W goes to pin 2L on the mtx ecu. this is the "power switch."
5v accelerator released and 0v accelerator depressed.

LG/W goes to pin 2F on the atx ecu. its the atx TPS potentiometer output.
0.5v accelerator released and 4.0v accelerator depressed.

LG/R is the wire that goes to the vane airflow meter. all I can tell is that maybe its the 5v supply to both the vane AFM and the TPS potentiometer.

So there's no way that I can see to give the mtx ecu the "power switch" it is expecting.

so I tapped the R wire that goes from the vane AFM's potentiometer to pin 2O on the mtx ecu. i hooked up a digital voltmeter and went for a ride. the voltage change seemed directly proportional to the accelerator ~3.0v at idle to ~0.5v at WOT.

so I guess i'll use the R wire on pin 2O as the throttle reference when I log data from my WB o2 controller (i'm going to try a JAW). the JAW will log o2 sensor output along with sources the user supplies, like rpm and throttle reference. this should be sufficient data to start tuning!

[dave0r]

rumor has it you can wire up the 4 wire TPS to a 3wire TPS ECU ..

take care with the voltage to the TPS
my 4wire GTX one is a 12v TPS as its stated on the TPS
yet some are 5v i,e my BA (2nd gen) 4wire TPS