Pedal Commander

[SleepyD7]

Super in depth response. Thanks for the education. My PC on my 370z was a dependable throttle response mod for 5 1/2 years but I guess it came with some risks.

 

[Digger]

The problem with the Pedal Commander specifically is that it's a really old design that was first invented before we all started getting adaptive PCMs (power control module/car's computer). These PCMs learn and adjust their baseline expected values as we drive. Thus, if you live in Death Valley, CA and you're always running hi IATs (inlet air temp), the PCM learns to not throw a CEL (check engine light) for routinely having excessive timing pulled due to the heat.

The system also learns your driving habits. As in, if you always nail it up the same onramp, even on a day where you want to go slow up the ramp, it'll hold gears without shifting to keep you in the powerband because it knows you usually rip it at that location. Thus, I'm simply getting at that the PCM is always watching and always learning.

Now, the Pedal Commander monkeys with this setup by injecting a controller between the pedal position sensor and the PCM. It modifies the signal the pedal sensor sends to the PCM by simply ratioing it higher. So, if you press 15% and have it set to the most aggressive setting, it will decrease the response time while also doubling the pedal movement to 30%. Thus, it mashes the gas quicker and harder.

Now, initially, what the Pedal Commander does doesn't trip the system so much because you're not doing 50 WOT pulls as soon as you leave the driveway. Most of your driving is going to fall well within the normal paramaters the PCM is used to. Over time, it'll detect the periodic higher or elevated unexpected numbers coming from the pedal sensor. So long as they don't meet whatever threshold is built into the tune, it does nothing. Over time, it learns that the throttle opens X quickly during Y (% throttle).

Where you will run into problems is if you routinely drive with it set to max, the PCM learns this and will go apesh*t if you ever remove it or dial it back down to the lowest setting. All of a sudden, the PCM is expecting the prior X and Y figures, but now they're suddenly much lower than expected. This is how you get the catastrophic limp mode, as the PCM thinks you're experiencing some undetectable power loss and it prevents the car from potentially hurting itself from an unknown problem.

This can also appear as a CEL without a limp mode if it's detecting increased/decreased numbers but not severe enough to warrant the CEL.

*The other issue I have seen is they can cause a limp mode if the actual Pedal Commander shorts out and causes a voltage loss from the pedal sensor. That'll brick the car pretty much outright. * - I don't have as much experience with Nissans as I do with some other brands. I have seen both Ford and Dodge cars go into emergency shut off / fail to start mode if the Pedal Commander is causing a short. I'm not entirely sure Nissan's PCM behaves in this manner or not.

That being said, I don't ever recommend using one of these. It technically doesn't do anything except add some faux throttle response. This can also be adjusted in the car's tune with a dyno/remote tune service. If you remap your pedal response in the tune, it will never throw a CEL, FYI.

Thank you for this informative and helpful post. This is the kind of info I was looking for. Others are sure to benefit as well.