TPS readings

[RI-Matt]

I recently noticed that my scanmaster and Tlink don't read the same as far as TPS goes.
On the scanmaster TPS set at .42
On Tlink the TPS reads .44
What up with that? Don't they read from the same source?

 

[kenmosher]

Yes they do ... it depends on how the rounding algorithm is working on both devices. It could be the actual value is right on the "cusp" and Turbolink is rounding up while ScanMaster is rounding down.

The range of the TPS is 0-5 volts and there are 255 A/D counts (raw data). Therefore, 1 A/D count = 5/255 volts. So if your raw count is multiplied by 5/255. However, calibrating TurboLink with the OTC, I found that they actually used 5.0955 volts as the reference voltage (and I can see 5.08 volts on my car when measuring the reference voltage for the TPS while the car is running)... so I used that as the range (0-5.0955)

So, if the reference voltage used by ScanMaster is 5.0 (I don't know this!) and TurboLink uses 5.0955, you'll get a very slight difference in readings depending on rounding and scaling. Bottom line is that it's close enough, since the TPS isn't really all that sensitive as long is it's in the proper range +- 0.02 or so.

 

[RI-Matt]

OK
I understood everything you wrote
Seriously thanks Ken
So it doesn't matter which one I set TPS to? Just so long as its within range?

Matt