How does the M5 power button work?

[M-J-B]

Stupid question if you know the answer I'm sure, but how does a button reduce or increase the power on the M5 engine?

Does it limit fuel, knock two pistons out of action or something is it really complicated?

[rsstman]

not sure about that, i was just going to answer the original question with.........

you just push it down!

[Goochie]

It simply changes the mapping in the ECU - You can get aftermarket "remaps" for other cars that use a very similar system.

[M-J-B]

Goochie said:

It simply changes the mapping in the ECU - You can get aftermarket "remaps" for other cars that use a very similar system.

I thought that, but wondered if like the MacLaren F1 car it also changed the number of cylinders used (as there's did last year whilst sitting on the grid so it was less likely to overheat.

[Diesel Meister]

For the E60

Elastic twickerwy

(ECU map - not sure of the recipe).

For the E39:

Throttle map - more agreesive (more power for a lesser opening)
Steering Wieght - heavier (less assiatnce? some would say better)

What I've always wondered was whether you could get an aftermarket fix that gave the std. throttle map with the weightier steering...

Edited by Diesel Meister on Friday 18th September 17:38

[skeeterm5]

The e60 m5 actually has 2 engine maps as standard and pushing the m button moves between the two.

S

[Diesel Meister]

I love the echo in here

[skeeterm5]

Its what comes of writing the reply while off line and then the damm thing synchronising later by which time someone else has posted the answer and I look like an idiot.

Like any situation like this I blame Bill Gates!

S

[Diesel Meister]

Dude, no worries - for E60 you expressed what I meant better than I did!

[blank]

M5 has a DBW throttle, no?

If so, it probably just changes the throttle map and/or rev limit. So when you floor it in "normal" mode, the throttle isn't actually as open as it could be.

[haybaby212]

my understanding is it changes the ecu map shapens the throttle and steering

[dubbs]

If we're referring to the M button then on the M6 it also tighetened up the whole car (EDC settings), reduced the traction control cut in, increased throttle sensitivity and gave you the extra ponies. P500S was different to P500 too but not sure what the difference was from memory.

[gilford]

The "POWER" button on the E60 gives an extra 100bhp, the button on the older M5 just makes the throttle a bit more sensitive like on the E46 M3

[mat205125]

skeeterm5 said:

The e60 m5 actually has 2 engine maps as standard and pushing the m button moves between the two.

No doubt you are correct, however an electronic map is just the controlling software for the engine. The real question is what differs between those maps?

Is the cam timing/opening/duration controlled differently?

Is the throttle opening controlled differently?

Is the fuelling controlled differently?

[Vixpy1]

mat205125 said:

skeeterm5 said:

The e60 m5 actually has 2 engine maps as standard and pushing the m button moves between the two.

No doubt you are correct, however an electronic map is just the controlling software for the engine. The real question is what differs between those maps?

Is the cam timing/opening/duration controlled differently?

Is the throttle opening controlled differently?

Is the fuelling controlled differently?

I would suspect the DBW simply does not open the throttle as far

[skeeterm5]

beyond knowing there are two maps it may as well be magic!

The other things mentioned like dsc, gear change etc are all user selectable via i drive.

S

[JeremyH]

I suspect by limiting the throttle to 80% of maximum (in non power mode) they would get the desired result without having to change the rest of the mapping as those changes would happen automatically.

[isee]

I remember reading some review where it mentioned that 400ps jsut starves the engine of oxygen or something like that and how dissapointing that was that 400ps offered no economy or advantage over 507ps because of that.

[Kenty]

The button can be configured for several settings such as gear change speed.
As far as I know the following happens:-
remap to give extra 107bhp using electronics only
increased throttle response
DSC is altered to give more driver control
suspension is stiffened for handling
gearbox change speed is increased to setting

and the engine noise is fantastic at 7000rpm

[mat205125]

JeremyH said:

I suspect by limiting the throttle to 80% of maximum (in non power mode) they would get the desired result without having to change the rest of the mapping as those changes would happen automatically.

isee said:

I remember reading some review where it mentioned that 400ps jsut starves the engine of oxygen or something like that and how dissapointing that was that 400ps offered no economy or advantage over 507ps because of that.

If this is actually the case then the 400bhp mode is completely pointless as it does nothing by restricting you from using full throttle. I've got an ankle that takes care of that, and in an emergency situation where full power might be instantly required, then I'd like to flick my foot and have it please.