I've noticed that some companies make sets of chips for our cars, and one of them is a "valet" chip that limits power so people parking your car don't go hot rodding around in it. Does anyone know what they do to make the chip limit power?

 

They probly either shut off the fuel at a certain rpm/speed or just cut timing out somewhere to make it feel like its slow? I would imagine its by rpm and speed.

 

I've played around with reducing power and limiting the RPM. I stopped after I kept forgetting to disable it when I drove the car. I used a method that reduced the timing once a certain RPM was reached. Then several hundred RPM after that cut the fuel. And PE mode was disabled.

This allowed the idle and light cruise areas to be unchanged. I was looking for for a mode that an inspection station or front end alignment shop could still drive the car but not beat on it.

The timing reduction worked well. It would reduce the power easily and smoothly. The fuel cut turned out to be rough. Too rough. If the timing had been cut back more the fuel cut would have been smoother.

In the end I felt that the best way to go would be two tables (SA & VE) specifically for reduced power mode. The SA table could be setup for the proper power levels. Then the VE table could be setup to provide the proper fueling for the reduced timing.

Can also place 0 VE values in the fuel table for a fuel cut function. By reducing the timing to nothing on approach to this area the engine would act as though it was just slowly dying.

RBob.