Throttle Position Sensor

[Conedodger]

I just discovered that I have a new '78 280Z TPS sitting on the shelf. I plan on using aTWM "Big Throat" throttle body. I'm wondering if the TPS is compatible with Megasquirt 3?

Edited January 16, 2017 by Conedodger

[NewZed]

1978 used a switch, not a sensor.  Idle, mid-range, and full (or close to it), but only those three conditions.  I'm not familiar with all of the possibilities of Megasquirt, but what you have wouldn't be considered a "sensor".

 

Here's something from the Megamanual - "

 

http://www.megamanual.com/v22manual/mwire.htm

 

"Throttle Position Sensor

The MegaSquirt^® controller uses the throttle position sensor (TPS) to determine when the engine is at or near full throttle (to shut off feedback from the O2 sensor), when the engine throttle is opening or closing rapidly (and needing an accel/decel enrichment), and when the engine is flooded and needs to be cleared. Some people have managed to make their engines function reasonably well without a TPS. This is not recommended with the standard code, however.

You will need a TPS that is really a potentiometer and not a switch. Many older cars had idle or WOT position switches instead of a real TPS. A real TPS gives a continuously varying signal with changing throttle. There are two wires on the external wiring schematic that go from MegaSquirt^® into the TPS sensor. These two MegaSquirt^® wires are +5 Vref signal and a sense line. There is a third wire going to ground. Assuming that you have a proper potentiometer TPS, then +5 Vref goes to one side of the pot, the other side goes to ground and the sensor line is hooked to the wip

Edited January 16, 2017 by NewZed

[Conedodger]

Oh! That's right! Never mind...

[jacky4566]

You dont really NEED a TPS for megasquirt. Accel enrichment can be done off MAP and i've yet to need flood clear mode. 

That being said NewZed has it right. Get a proper linear potentiometer. It make it much easier to datalog and there are many fun features that need it. 

[madkaw]

If you want to run ITBs eventually you will want a TPS.

Might see if the 240sx TPS will work with your TB.

Another reason to have a full range sensor is for data logging . Trouble shooting and tuning would be easier with one more data point

[Conedodger]

My throttle body is the old TWM "Big Throat" which used the stock throttle switch so the shaft size is the same. 240SX?

[LanceVance]

The 240sx TPS does fit the TWM shaft, but the two bolts/screws are placed closer than the standard switch. Plenty of meat to drill and tap.

Edited February 24, 2017 by LanceVance

[Conedodger]

Lancevance,

Any idea what particular year 240SX would be best?my neighbor is the national sales manager for Autozone. He can get me whatever I want but says there are a couple of model numbers.

[LanceVance]

I don't recall which year/generation I bought mine from. When in doubt I usually just go for the newest possible option (98' S14 in thus case), and keep the receipt...

[Conedodger]

Thx!