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Author Topic: TPS wiring?  (Read 2932 times)

Ryeoon

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TPS wiring?
« Reply #15 on: April 21, 2014, 08:00:15 PM »
Any more detail as to what that means? Don't quite understand it. I've seen a few people with it unplugged.
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gtsr

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TPS wiring?
« Reply #16 on: April 21, 2014, 09:13:20 PM »
The kick down is when touches idle contact inside TPS when throttle is closed and this tells ECU to switch to kick down tables x2 that kick rpm up to prevent rpm needle from dropping below idle rpm and engine stalling when under load (with lights, aircon, etc on). Random stalling can be due to the idle contact bending over time. On new TPS (series 2 R33 onwards) they used voltage instead of idle, WOT contact pins like found inside R32 TPS.

From what I understand from pulling apart a TPS, one plug is the WOT and idle contact which is connected to the WOT, idle contact pins at each end of a curved track on circuit board inside TPS. The other plug is connected to the circuit board which reports to ECU the position of throttle and does this via volts 0-5V.

At idle the voltage is around 0.44 volts (idle contact) and at WOT it should be 4 volts.

The TPS is basically an electronic version of an accelerator pump if you are familiar with carb engines. Does the same job.
« Last Edit: April 21, 2014, 10:24:36 PM by gtsr »

Ryeoon

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TPS wiring?
« Reply #17 on: April 21, 2014, 09:46:47 PM »
Ahhh, I see. Kinda wrapping my head around it. I guess that kinda explains why when I had my car running without TPS set, it would drop suddenly before accelerating if I throttled. Sometimes stalling it.
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gtsr

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TPS wiring?
« Reply #18 on: April 21, 2014, 10:15:19 PM »
On my car, could wiggle TPS plug facing engine and nearly made engine stall. Sometimes people pull on the wires or knock the TPS plug when working on engine which causes problems.

Also when on idle contact inside TPS and car is not moving, stock ECU switches to idle stabilisation tables which adjust's ignition timing + 5 degrees or - 5 degrees or so (not actual figures on ECU, but you get the idea). If use a timing light it picks up on ECU sending signal to 1st coilpack (telling ignition module when to fire 1st coilpack) to adjust ignition timing + or - 5 degrees which makes CAS hard to set.

That's why most use the sparkplug cable trick from coilpack to sparkplug to set CAS, as shown in Link ECU manuals (GTS Link ECU manual is usually where you find a photo, explanation of how to do it, etc or ring Link and ask). It gives a solid, accurate ignition timing figure to set CAS properly.
« Last Edit: April 21, 2014, 10:23:03 PM by gtsr »

Ryeoon

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TPS wiring?
« Reply #19 on: April 22, 2014, 04:56:49 PM »
I'll look up that spark plug trick as I want to check my CAS setting.

What would be the point in having the one plug directly on TPS not plugged in? Keeping it in the same mode as driving when on idle?
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downtrail

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TPS wiring?
« Reply #20 on: April 22, 2014, 05:14:41 PM »
its not needed for aftermarket ecu only the plug on the little lead this is where the tps sweep is read from 0-100 throttle position idle can be worked out from load points etc you can jam the sensor on in any position and  use the tuning software to callibrate closed and wot readings easy as.  factory computer uses the plug directly on the tps for idel etc as thats just the way they worked there ecu software at the time.
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gtsr

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TPS wiring?
« Reply #21 on: April 22, 2014, 05:24:24 PM »
Not sure, as stock R32 ECU needs both idle, WOT contact's, 0-5V to work.

As downtrail has already said, if using an aftermarket ECU, might be trying to immitate a fly by wire setup with 0-5V only and it might use software voltage triggers on ECU side for idle, WOT contact (same type of voltage based TPS idle, WOT trigger setup as later model R33 stock ECU).
« Last Edit: April 22, 2014, 05:25:26 PM by gtsr »