tps hook up only 2 wire's????

[MaTTSuN]

ive had my TPS hooked up on my 78 Z i put a 81 turbo motor in and there was only 2 wires to hook up there is one more wire that does not hook up to anything. ive changed TPS plugs i think the turbo TPS only had 2 wires but it doesnt seem right

where if anywhere can i hook up the 3rd wire

.....

 

 

Matt

[veritech-z]

One of the three wires should be a ground, what color wires are you using, and which one is left over? Usually, a tps gets a power in, a power out reference signal, and a ground.

[MaTTSuN]

thats what i was thinking there is a green and blue from the harness andthey take up the 2nd 2 wires if you go from front 2 back.

the front wire is bare....

[280Zone]

Mattsun,

 

So from front to back on the TPS you have blank, then green then blue? Or blank, then blue then green?

[evildky]

the stock TPS uses only 2 wires, thats why it won't work with megasquirt, it's just an on off switch

[mario_82_ZXT]

Yea, the stock turbo ecu just requires continuity at that switch during idle.

 

For MS you need a true TPS, one with a potentiometer to tell the ECU exactly where the throttle is.

Mario

[GrayZee]

Yeah, just run a 240sx one.

[MaTTSuN]

ok but i dont run MS just trying to get it to run good...

[GrayZee]

Ok, well only two wires are actually needed. The 3rd wire is to indicate full throttle position has been achieved. Basically it's just a on/off switch. I imagine the full throttle position is used to turn off any existing air conditioning units to have maximum engine power at full throttle. The wire that actually gets used by the ecu is to indicate that the engine has no throttle input and is essentially idling. Otherwise known as "limp mode" The ecu just uses a very basic program to make the car idle. Once the TPS is opened the fuel/timing maps take over and adjust to the varying condtions. The third wire is simply the common connection between the other two wires.

One time I hooked up the common wire correctly but had the other one hooked to the wrong terminal. The engine ran fine until you put the hammer down and the car lost ALL power, because the ecu thought that the engine was in idle mode. Ha ha.. took a couple of days to figure that one out!