Absolute throttle position - correct %?

[TridenT]

So, intuitively, I would think that you want the absolute throttle position % to be 0 when idling and 100% when the pedal is on the floor. (if not sooner?)

My honda civic says about 9.8% at idle. It idles at about 700rpm while the engine is fully warmed up. I didn't look at on the floor because the car was on and I was right next to my neighbors.

 

[phucheneh]

Absolute throttle position will not be 0% at idle. Nor 100% at WOT, most likely.

I'm not positive, but I think it is going off of a full 0-5v sweep of the TPS. But the ends of that range are never seen...more like, say, .6-4.6v. Which on a full 5v scale would be 12-92%.

 

[Fenixgoon]

the throttle mapping may also be rate dependent - so how fast you press down on the pedal.

 

[JCH13]

It's completely arbitrary, and there is frequently an option to re-calibrate your TPS.

Many cars only use TPS for acceleration enrichment and other second- or third-order controls, so great accuracy isn't needed. The car's fueling and other primary controls will be based off of a MAF or MAP sensor or something more accurate.

 

[Squeetard]

TPS can never be 0% at idle as idle always varies. It takes more throttle to idle a cold engine at a certain prm than a warm engine that is now running in closed loop.. They need some room to move up and down as they hunt to hit a certain rpm.

 

[JCH13]

TPS can never be 0% at idle as idle always varies. It takes more throttle to idle a cold engine at a certain prm than a warm engine that is now running in closed loop.. They need some room to move up and down as they hunt to hit a certain rpm.

IAC is generally controlled through a valve separate from the actual throttle plate.

 

[tortillasoup]

It depends on the vehicle, the TPS position is usually within a range, some vehicles start at 10tps with no throttle input and stop at 85tps at full throttle input. It's actually in my experience uncommon to see 0% tps for no throttle and 100% tps for full throttle as the computer typically uses those extreme numbers to indicate a bad TPS.

 

[Railgun]

The ECU will use voltage as a reference to a bad TPS, not position. 5v usually for a bunk sensor (eg, a short).

You calibrate voltage to its relative position. There is some play, generally, to adjust it physically. While the voltage is within a range, the position of the throttle can certainly be 0-100. 0= your foot's off the gas. The IAC generally can have enough leeway to deal with things in a 0 position condition. As others have mentioned, there may be cold start circuits to open the throttle electronically or mechanically until it's properly warm.

 

[Zenmervolt]

IAC is generally controlled through a valve separate from the actual throttle plate.

Idle is controlled by the separate valve, but in most cases the throttle plate never completely closes either. The idle control valve is used to fine-tune beyond the fixed minimum opening of the main throttle butterfly.

ZV