[hemiitis]

Below is a screenshot from the Diablo Dataviewer of a short WOT run in RumBee using the Stock Tune, stock shift points, and stock shift firmness. The only changes I made from the stock tune with the Predator were to turn off my rear O2 sensors and to lower the fan settings by ~23 degrees since I have a 180 tstat.

The graph below represents a short WOT run from 2nd gear to 3rd gear. The vertical cursor was placed at the center of the shift (halfway between the peak rpm in 2nd and the minimum rpm in 3rd). ST KR reached 5 max and LT KR was 0.0 throughout:

The blue trace is the Throttle Position Sensor (TPS) and the red trace is the Accelerator Pedal Position (APP). Both of these are shown in %.

Why does the TPS exceed 100% during this data log? I can understand that if the TPS was zero when the APP is zero that the engine would choke from no air flow, but why does the TPS exceed 100%?

Please let me know if I forgot to provide some info...

Thanks in advance. :thumbsup:

 

[hemiitis]

Can anyone explain why my Throttle Position Sensor exceeds 100% in the Dataviewer screenshot I posted above? I'm wondering if I have a calibration problem, or sensor problem, or if this is normal...

If any more info is needed, please let me know. Thanks again. :thumbsup:

 

[GLHS837]

sounds like diablo isnt seeing TPS correctly. The MSD Dashhawk has the opposite problem, it sees TPS about 10-15 percent shy of reality. Reports it as %75 at WOT< when in reality it actually opens more like %85-90. when asked, SRT engineers stated that the max open position is in that area, and making the blade open farther does not increase airflow.

One member of another SRT-8 forums actually built a bench setup of the Jeep SRT-8s electronics for test, and physiccally opened the throttle plate while watching the readouts, and verified this info.

 

[hemiitis]

Thanks for the reply GLHS837!

That makes me wonder if I'm looking at the actual position read from the sensor, or the position being command to the sensor (i.e., setpoint value).

If it's the setpoint and a simple PID controller is being used, then I could account for the value going over 100% as "windup" (assuming that the designers did not include anti-windup logic in the controller). It's hard to believe that's the case in this day and age. I can't see it being much of a cost savings to use a control loop that allows windup vs one that has anti-windup logic, and it would make the control loop much harder to tune.

If it's really the throttle valve position being read from the device, then I still don't understand why it would go significantly over 100% unless it's a calibration error or a bad sensor. I'm not getting any codes, including a TPS failure. Seems to me I'd get a code if it was a bad sensor or if it's really supposed to max out at 100% and showing 127%. That's a 25% error in the reading (more if you consider that it really can't physically open to 100%).

I've posted on the Diablo site, too, so maybe someone over there can at least confirm which of those two values I'm looking at.

 

[hemiitis]

I asked Diablo about the TPS values I'm getting, and their answer was:

127% is correct on the new 09 models.

So even though I have an '08 Bee, I guess my TPS goes to 127%. Seems like that should get me more air (and therefore power) than those of you than can only get 100% out of your TPS. :biggrinjester:

When I asked about why it could go above 100% they said:

Thats a question for Chrysler, we just interpret the data and make changes, we dont try to figure out why they do some of the stuff they do, lol.

For anyone interested, here's the thread on the Diablo website about this same question:
http://www.diablosport.com/index.php?name=PNphpBB2&file=viewtopic&t=16530

Thanks for playing. :thumbsup:

 

[GLHS837]

So, the %127 value is correct, but that does not mean that the blade is actually pasing through 90 degrees

 

[hemiitis]

But, somehow it feels better than 85%. lol

 

[Nickrt]

My 2009 only gets to ~75%.

 

[dwilsonjr74]

I have the same magnaflow and have nothing but good things to say, my brother got his from ebay but I wanted a valid warranty(I have had problems with ebay sellers before) so I got it here. magnaflow 16530, or you can try one of the vendors here on the forum selling magnaflow, they are allways having sales/specials on the forums. It is nicely built and sounds great I think.