Problem with TPS% reading 30 at idle

[lionelhutz]

The '7747 doesn't auto calibrate the TPS. So, lets assume the '7747 ECM uses %TPS internally.
- What voltage does it use as 0%?
- What voltage does it use as 100%?
- How could you not calculate the %TPS from voltage when you know the PCM never does any calibration on the %TPS?

And the bonus question - how did you know the %TPS you were trying to calculate for a '7747 was wrong when there is no %TPS output in the datastream?

[Six_Shooter]

The '7747 doesn't auto calibrate the TPS. So, lets assume the '7747 ECM uses %TPS internally.
- What voltage does it use as 0%?
- What voltage does it use as 100%?
- How could you not calculate the %TPS from voltage when you know the PCM never does any calibration on the %TPS?

And the bonus question - how did you know the %TPS you were trying to calculate for a '7747 was wrong when there is no %TPS output in the datastream?

Because I'm smart.

When closed and WOT do not match 0 and 100%, and then when manipulating the formula causing any point in the throttle movement to be off. That auto calibration is what made it possible to have TPS % in the datastream.

I also believe that the tables based on TPS % are just approximations that someone has put in there because it seemed to make sense when they disassembled the the code. There have been many inaccuracies of the $42 code found that have perpetuated to this day, because that's how it was said to be originally.

The long and the short of it is, it's not as easy as you want to believe it is.

[lionelhutz]

Ya, SMRT smart.

I wouldn't be surprized if the '7747 doesn't use %TPS internally at all. So, when you tune a %TPS value you're probably adjusting a value that is using the TPS voltage (the 0-255 counts value).

Getting all wound up because you can never make a display show 0% when let off the pedal or show 100% when you put the pedal to the floor is rather dumb when that value has no correlation to what is being used inside the ECM.

Here's the only way I can think of to test your %TPS meter on a '7747. Set the TCC unlock (or lockup) all at the same %TPS. Then, drive and observe the TCC lockup vs the %TPS meter. I personally couldn't be bothered. The last time I programmed a '7747, the calculated %TPS got the TCC table close enough it works like I expected.

[ony]

here is a file eagle mark was working on be for he got sick. the 5.2 adx shows 0 % at .50-51 on my truck. if I remember it went to 94% which it would read different on another tps.

[AlpineCJ5]

here is a file eagle mark was working on be for he got sick. the 5.2 adx shows 0 % at .50-51 on my truck. if I remember it went to 94% which it would read different on another tps.

thanks for the file. I offset all my TPS% values by 30 in the old XDF to compensate, and when I loaded the one you posted, my TPS% numbers were exactly what I thought they should be instead of 30% high. I feel like all TPS calcs should've been done in volts to negate this discrepancy, but it must've made more sense at the time.

thanks guys.

[ony]

the only % setting I remember messing with was when it was time to enter pe mode which I have a v6 and I try keeping it at 70% throttle and a 2.5 second delay.

[AlpineCJ5]

This was an incorrect assumption on my part. The values in my tables are real, and don't need to be offset. It is simply the readout from the XDF. Now what you guys were saying makes more sense. Now that I really think about it, the XDF and ADS files are totally separate and of course a readout from one wouldn't affect the other. Haha. Live and learn.