Linear pot used on throttle pedal for DBW.

[blacksupra]

I was thinking of using the motec 75mm linear pot, or shortest one available to control a nissan vq35 throttle body. acceptable? or should i be trying to fit a nissan throttle pedal? mounting a pot to the existing pedal seems much simpler.
application is a supra turbo with a m880.

[pftuning]

I was thinking of using the motec 75mm linear pot, or shortest one available to control a nissan vq35 throttle body. acceptable? or should i be trying to fit a nissan throttle pedal? mounting a pot to the existing pedal seems much simpler.
application is a supra turbo with a m880.

I'd get the pedal; I think it mounts pretty nicely.
Get the connector pigtail with it; I think those fine pitch connectors are not easy to get.

[stevieturbo]

I think most pedal's have a dual track sensor. For safety purposes.

Not sure if the Motec would need both though ?

Reverting to a single sensor for pedal position. Whilst I'm sure would be fine 99.9% of the time...

The dual track is to make sure things are safe 100% of the time.

[Holmz]

I was thinking of using the motec 75mm linear pot, or shortest one available to control a nissan vq35 throttle body. acceptable?
...

Just making sure that by control you mean "cause and effect", and not that the linear pot is a transducer... Because it is only a sensor.

As an aside...
The shortest one available would be pressure sensor.
and then the pedal would not move at all...
Surely someone has tried that if there was a need.
(I suppose it would be a throttle pad, rather than a pedal)

[blacksupra]

I think most pedal's have a dual track sensor. For safety purposes.

Not sure if the Motec would need both though ?

Reverting to a single sensor for pedal position. Whilst I'm sure would be fine 99.9% of the time...

The dual track is to make sure things are safe 100% of the time.

revisiting this... if i use 2 x linear sensors (rather than retrofitting a complete pedal assembly from a car already fitted with drive by wire) should i mount them in a one pushing / one pulling configuration? or can they both be mounted behind the pedal?
does the ecu need to see rising resistance of one sensor versus the falling resistance of the other or just needs the 2 inputs regardless from a safety aspect?

[David Ferguson]

You can mount the sensors parallel, then just wires them opposite of each other. So one sees rising voltage with increasing pedal position, and the other sees falling voltage.

There are dual-output rotary pots available from Penney & Giles that are intended for just this type of use. By using a contact-less pot, you can eliminate wear problems.

[Scott@FP]

Majority of pedal position sensors are actually Hall Effect. Put an OEM DBW pedal assy in it. Cheaper and easier in the long run.

And yes the two sensors need to work opposite on voltage vs. pedal travel.

[mstech]

Not actually true, some OEM pedals have both tracks rising with increased opening position, and others have the secondary track only tracking the primary (either parallel or opposed) to a certain point, and then they stay at that fixed value.

[SportsCarRacer]

Very correct mstech! Most modern hella dbw pedals have 2 tracks with same rising slope with increasing pedal, with secondary tp2 being exactly half the slope of primary tp1 sensor. Method mainly used to faciltate obd diag of pedal for safety case and improved driveability & functionality in failure event.

stateof the art is ine analog track and one digital track( eg pwm)...these are hard for existing mx00 ecus, but I strongly believe m1 can interpret these newer mixed signal sensors.

a factory style pedal is best due to detailed measures to reduce hysteresis and "backlash". This is very hard to replicate with linear pots and rodends.

also if its a racer, big benefit of oem pedal is direct pedal swap in event of fault which most likely could get away with with resetting hi & lo limits in emergency. I recentky tested a batch if 20 random helka (gm) pedals and all but 1 if the 20 required no recal if end points when plugged in due to very tight tolerances on output vs position and endstops of prodn part. The one that required a recal wss 0.5% out at wot!!! Test was conducted in event car came in with oedal fault oedal could be swapped and car sent in its way straight away..difficult if nit impoosible for aftermarket pot solution!!!!!!

Please note..as per motec recommendation for dbw, EVERY time the oedal is changed the lo & hi limits MUST be reset for safety on bith driver pedal inputs tpd1 & 2.