Throttle Position While Making WOT Run - JB4

[tonyd86]

So I logged a few WOT runs on the JB4 earlier today and noticed that my throttle position was only reaching 96 and not 100, according to the CSV file and graph. Not that it's a big deal, but has anyone else had similar readings for their throttle at WOT? I do have a pedal tuner installed, so I'm not sure if that's making a difference or not.

 

[Volfy]

Mine also tops out at 96% Throttle with 100% pedal position. I'd say that appears to be normal. With a butterfly-valve throttle body, % opening of the throttle plate does not correlate linearly with actual SCFM air flow. The first 50% (45deg of the full 90deg) travel account for more than 50% of the max SCFM. By the time the throttle plate is near fully parallel with the flow direction, the last few degrees of travel probably don't add much more SCFM, if any.

Besides, factory engineers might have calibrate 96% as full-open (100% parallel), such that if the ECU ever sees more than 96%, it knows the throttle body might actually be worn/faulty so as to allow over travel. Over- and under- range detection is quite common in sensor and actuator calibration for self-diagnostic purpose in industrial applications. I'd imagine automotive world is no different.

 

[tonyd86]

Got it. Thanks for the info and knowledge!

 

[canucklehead604]

i see the boost hit almost 25psi - big numbers! AFR looks good. my JB4 plots were always a bit of a mess since i have to let off to shift. so the throttle, pedal, etc, always dip and makes the graph tougher to read.

 

[buddy712]

What year is your car. The JB4 has always read 99 for throttle. Also, what ECU tune do you have?

 

[tonyd86]

It's a 2020. I was running Map 2 at the time.