Thread: Chipbox for M5
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      01-15-2013, 12:47 PM   #2
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Originally Posted by MCM5 View Post
Has anyone heard or tried this ?

For F10 M5, it claims to increase performance to 615 hp & 750Nm.
One good thing (if true) is that you can unplug it & go back to stock setting when going to BMW for service.
This product is basically a very crude way of increasing power. It's been very popular in the diesel tuning arena after the common rail diesel engines came along.

The power box simply alters the signals that some sensors (on a common rail diesel it's the fuel pressure sensor) give to the ECU. Fooling the ECU to believe that it's running a low fuel pressure and increasing fuel pressure to increase power.

Say that the (diesel) fuel pressure is supposed to be 1800bar under normal conditions. The fuel pressure sensor gives a certain value/feedback to the ECU when the pressure is 1800bar. By bypassing the signal via the power box and altering that signal the ECU believes the fuel pressure is just 1500bar and increases the signal to the fuel pump and gets the fuel pressure higher. This then leads to the ECU receiving the correct fuel pressure feedback for 1800bar, but the real fuel pressure is 2100bar...!!!

This is probably also the same method applied to the M5. Most likely both fuel and boost pressure signals are altered to fool the ECU into believing that it's running low boost and fuel pressure...

The power boxes are really nothing more than a added resistance in the circuit to some of the sensors...