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Torque » Torque OBD ECU Scanner » Torque Discussion / Ideas » Throttle Position Readings

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Author Topic: Throttle Position Readings
PwnedXJ
Member
Posts: 192
Post Throttle Position Readings
on: May 23, 2011 (GMT)

I am getting a constant reading of 16% in the Throttle Position display for Jeep Cherokee 1996. This is so even where the engine is at idle or in motion. I would have expected this to vary from 0% to 100% depending on various factors that affect the throttle position. I do not have the Check Engine light on and I have no DTC stored in the ECU. I wonder what is going on here.

Timmay
Member
Posts: 81
Post Re: Throttle Position Readings
on: May 23, 2011 (GMT)

I have tested several different vehicles, using a few different OBD loggers, and to be honest I think this is an issue on the ECU side! Maybe 1/2 of the vehicles that I looked at the TPS reading would display it normally (ie foot off the throttle 0%, throttle pedal to the floor 100%). The problem as far as I can see is that the manufacture does not necessarily use the full range of travel available on the actual potentiometer used for the TPS, which is located on the throttlebody, not the Accelerator pedal (which has a separate sensor on drive by wire cars)

I had thought about doing a few studies on driving styles in my college work, and how the TPS relates to vehicle fuel consumption etc but have not got around to it. But anyways, what I was going to do was record a someones vehicle trip, and at the beginning of the trip get them to fully press the throttle down when the vehicle is off. Then in the .CSV file that was logged, I could look at the a), what was the minimum TPS reading (ie 7% would really correspond to 0% throttle movement at the pedal). Then b), I could also look at the reading logged when the driver fully pressed the throttle, and if this was for example 92% I would then have the true range of the throttle pedal. I could then scale all the values that were inputted to the logfile to match this pedal range.

piemmm
Administrator
Posts: 6134
Post Re: Throttle Position Readings
on: May 23, 2011 (GMT)

Hi

You may find that after a preset RPM in your engine, the manifold throttle automatically closes by a certain amount (this is true for the VW Fox which drops 20% from it’s maximum when reaching high RPM)

This is because the throttle position is the actual actuator on the manifold. If you have 0% on this, then you basically stall your engine as you have cut off the air supply :)

PwnedXJ
Member
Posts: 192
Post Re: Throttle Position Readings
on: May 23, 2011 (GMT)

Sorry guys the first post is not correct. There must have been something wrong when I first took the TPS readings. I took new readings earlier in the evening and i can confirm that the TPS is active. However I made the following observations:

1. TPS reading at idle is 16.1%
2. Any time I step off the gas TPS comes down to minimum of 16.1%
3. With the key at ON position but car not running TPS reads 15.7%….

So just wondering whether these are normal readings? :)

piemmm
Administrator
Posts: 6134
Post Re: Throttle Position Readings
on: May 23, 2011 (GMT)

They should be – the open / closed values for TPS at idle/full load vary depending on the type of engine and map. It’s normal for it to not read 100% on some vehicles at full load, but 100% on others

I’ll see if I can find a decent pedal PID that works on most vehicles and try to add for the next release.

Thirsty
Member
Posts: 1
Post Re: Throttle Position Readings
on: January 5, 2021 (GMT)

Hello.
What happens with a direct injection diesel, e.g. Ford Ranger/Mazda BT-50 2.5 litre, with the TPS readings?
Thanks.
Ross

Australian Male.

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