If anyone has installed aftermarket computers to EA81T or EA82 stuff... Did it like TPSensor or TPSwitch output or not even use it? I have found EA82 TPSensors start as high 5V for idle and only drop 0.5 V to ~ 4.4 - 4.5V

Whereasit appears more modern TPS has an industry standard of 0.5V for idle up to 4.5-4.8V for full throttle

So, makes me wonder if

aftermarket ECUs needed a different TPS for best results

 

¿?????????????

Going by the diagram in my 1990 FSM for EA82 -

The TPS is a pot, one end to GND, top end to +V  - probably 5V the computer ICs run on, but I have not verified.  The output  [wiper] pin should go from near 0 to near power rail.  I would have to analyze a bit to determine if 0 = no throttle or 0 = full throttle.  But either way, the signal should range from  roughly 0 to 5V, varying with position, measured from wiper to GND.

If they followed their conventions of wire colors, the black wire is GND, and goes to the 0 throttle end of the pot, and one side of the switch, which is closed at zero throttle.

An aftermarket ECU should have details in it's manual about the signal range and it's requirements.

Right, thanks Dave. I wonder if I tested the wrong way

I tested and got a result,  but not using the gnd terminal of the TPS. I grounded the TPS gnd terminal and dmm ground lead went to gnd as well

Read the 5.0 V supplied and only saw it drop 0.5V on two different units. Both units tested as per manual resistance specs.

Both had higher reading closed throttle

In my case there is no true ECU as it is an enrichment device for propane. Propane system without this control will run quite well but need to lean it off a bit to let enrichment device do its work

It comes with basic instructions but now have more info on it, in that it needs to see pot readings for enrichment over riding O2 which I think will trim things on cruise

 

I dont recall anyone having issue with EA82 ser 2 TPS's used for aftermarket computers.

Its just a variable voltage divider. 5v across the 2 outer connections and the signal is taken from the slider

 

The FSM diagram I have shows 3 wires on the TPS

Terminal 1 = power supply (White)

Terminal 2 = sensor signal (red)

Terminal 3 = Ground (black)

But on my RX, terminal 2 is white and terminal 1 is red

I'll upload photos this arvo

I got my little efi hardware universal TPS in the mail today

It uses white as power supply 5V (+)

red for signal to ECU

and black as GND

 

I need to make up a bracket to hold its 36.5mm centres mounting before testing without fiddling and fumbling

 

Hope I get more that 0.5V range out of it

Curious to know your Voltage range results from closed to fully open Gannon

Now waiting on a waterproof 3 pin loom plug...at least I know what wires I need to feed into the engine bay now.

 

I salvaged 99Impreza shielded cable for the TPS to "GASECU" seeing as though could not find previously carefully reclaimed and hoarded shielded collection :)

 

Ok so I tested my TPS and it isnt working like it should

I have 118.7Kohm resistance between pins 1 and 3

I have 22Kohm between terminals 2 and 1 at closed throttle and 13.4kohm at open

Applied 5v to outer terminals and I got 0.4 v at closed and 1.0v at open

Interestingly, the FSM shows a round plug for the TPS but mine is oval with a smear of silicone on the cable entry, and ive seen 3 others the same

I just tested the Ej20 TPS (4pin) I have and it works so lets see if it lines up with the flat on the EA82 throttle shaft (keeping in mind it rotates the opposite direction

How did you go with your universal TPS?

It is in and functioning as required. Cannot say same for the computer. Seems to have a timer in it not declared. Cuts out after 70 seconds if left to idle at op temp

How do you know it cuts out?

Seems odd, does it cut back in or does it require a restart?

Engine stops running and can predict when it will watching seconds tick over.....68.69.70 ...wait for it....stop

Any update on your issue?

Not yet. Given supplier enough time to respond email so will call. Swear I hear him squirm when he hears my voice