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Discussion Starter #1
Hi all i'm a new member here and my M5 has yet to arrived.
However, I have a question regards to P400.
How does the P400 works? Does it restricts the engine from reaching max RPM, shut down half bank of cylinder (though I don't think that's what BMW would do), or restricting the air/fuel going into the engine?
 

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I am no expert
But I would think it reduces the timing and the fuel
 

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dteray1 said:
Hi all i'm a new member here and my M5 has yet to arrived.
However, I have a question regards to P400.
How does the P400 works? Does it restricts the engine from reaching max RPM, shut down half bank of cylinder (though I don't think that's what BMW would do), or restricting the air/fuel going into the engine?
It restricts the throttle butterflies in each cylinder to 80% (maybe 90%?). P500 opens them all the way.
 

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90% butterfly opening
 

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Discussion Starter #5
So this means that I can rev all the way up to the red line except that at WOT the throttle will be open at only 90%, right?
 

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I was told that the Vanos oil delivery system also plays a roll in P400 to P500 mode. Maybe the oil pressure is changed?
 

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Finally! Someone asks!

This has been on my mind for two weeks now, just never gotten around to posting it. There has to be more than simply 90% throttle, I mean 100+hp from 10% more throttle body opening? That'd be crazy.

Looking forward to hearing the answers...
 

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joshkerr said:
I was told that the Vanos oil delivery system also plays a roll in P400 to P500 mode. Maybe the oil pressure is changed?
From what I understand about the way VANOS works, it basically varies oil pressure in the head to achieve variable valve timing; More oil pressure = larger valve lift = higher performance.

If the throttles only open 90%, it would make sense for the valve lift (and consequently VANOS pressure) to be reduced as well.
 

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M5converter said:
Finally! Someone asks!

This has been on my mind for two weeks now, just never gotten around to posting it. There has to be more than simply 90% throttle, I mean 100+hp from 10% more throttle body opening? That'd be crazy.

Looking forward to hearing the answers...
I don't know the answer to the question, but clearly more distinquishes P400 from P500 than the maximum degree to which the throttle bodies are allowed to open. You can be driving along in P400 at 3000 rpm with very little applied throttle, and when you switch to P500 there's an entirely different, "liberated," engine sound. And this new sound to me has a quality that's different from just applying a little more throttle, so I don't think that this new sound simply represents a more aggresive throttle response to a given position of the accelerator pedal. I could be wrong though.

Those of you going soon to the BMW M5 Experience should ask that P400 be defined. The last time I was there, we were offered a Q & A session with a technical guru.

Richard
 

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M5converter said:
Finally! Someone asks!

This has been on my mind for two weeks now, just never gotten around to posting it. There has to be more than simply 90% throttle, I mean 100+hp from 10% more throttle body opening? That'd be crazy.

Looking forward to hearing the answers...
It is simply throttle... remember we are talking about 10 cylinders at 90%...
 

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rsteele said:
I don't know the answer to the question, but clearly more distinquishes P400 from P500 than the maximum degree to which the throttle bodies are allowed to open. You can be driving along in P400 at 3000 rpm with very little applied throttle, and when you switch to P500 there's an entirely different, "liberated," engine sound. And this new sound to me has a quality that's different from just applying a little more throttle, so I don't think that this new sound simply represents a more aggresive throttle response to a given position of the accelerator pedal. I could be wrong though.

Those of you going soon to the BMW M5 Experience should ask that P400 be defined. The last time I was there, we were offered a Q & A session with a technical guru.

Richard
I raced GT cars for many years and several of these cars have had a choice of engine ECU map. Each map can be selected by just switching from one to the other. Map 1 would be for qualifying Map 2 would be race and Map 3 would be for sitting behind the pace car. Each of these maps would change the amount of fuel to the injectors and the engine timing. F1 cars use the same system. When you push the "M" button the whole car becomes more responsive. I would doubt if it is throttle opening.
 

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The sport button on my M3 does the same thing... it also has a remaped ECU from DigiTec and there is noticable more difference pushing sport in the M3 than my E39M5.

My guess would be that the M button and the "sport" buttons on older M-cars is a different ECU program all togeather, not just the throttle body opening is wider but also faster.
 

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Discussion Starter #13
I would have to agree Isimmo.
With the whole "not opening throttle at 100%" would not be logical. Assume that you are crusing at 6000 RPM and you decided to switch to 500S from 400 you will instantly get another 100bhp hike, to me that is kind of dangerous. You can will probably spin its rear wheel like having a shot of nitrous.
I guess I would conclude that the car has 3 sets of mapping where 500 gives you a different cam timing/lift (with VANOS?), more fuel, and advanced spark ignition.
 

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I remember reading its a different ECU map, which in turn also controls the butterfly opening etc.. so in effect yes it has 3 different ECU settings, P400, P500 and P500S.. but I also think that somebody somewhere knows more on this topic ;)
 

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This is a subject people like me could talk about for hours, basicly it comes down to what has been said above, controlling the butterflies and the throttle so you have less power but in reality it's much more complex then that.

In reality it's all about LaPlace transformations, domains, root locus plots, feed forward regulators, amplifiers, dampeners, integrators, differantiators and alot more mathematical mubojumbo an untrained person wouldn't understand.

Basicly deppending on what you want your system (in this case a car engine but it might just aswell be a oven or rocket) todo you can put in different mathematical variables and your system will do it. This is a subject which has been researched to death and which is so wide that it's impossible to explain here. For convenience even engineers and scientists do not make up their own equations but use ready made equations which are universally true to the kinda of system you are controlling. There are equations for ovens, DC motors, servos, rockets, car engines, water plants, oil drilling, etc. you name it and I'm sure I can find the equation for it.

But put in a way an average joe could understand. It selects a different map in the ECU which results in different control responses and which in turn means less power and a slower build-up of power which in turn means less fuel consumption.
 

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So, basically, it is an entirely different ECU Program.

You have, as previously stated by Taipan, 3 different modes

P400
P500
P500S

All of which have different degrees of ECU mapping, throttle adjustment, spark plug timing, air/fuel ratio, and camshaft timing I would guess....

Hoorah for BMW. I knew that this car was more incredible than a lot of people thought.
 

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M5converter said:
Hoorah for BMW. I knew that this car was more incredible than a lot of people thought.
Not really. Cars with Sports buttons have been around for ages now.
 

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frylord said:
...This is a subject which has been researched to death and which is so wide that it's impossible to explain here....But put in a way an average joe could understand. It selects a different map in the ECU which results in different control responses and which in turn means less power and a slower build-up of power which in turn means less fuel consumption.
Actually, if the P400 execution were to be distilled into plots of torque and horsepower against rpm and placed on the same chart with the plots for P500, I suspected most of us would be satisfied and unconcerned with the complex means by which that result was achieved.

I haven't noticed that P400 results in significantly less fuel consumption when extracting similar driving performance from the car. Have others experienced better fuel consumption in P400?

Many of us spend as much or more time driving in P400 than in P500! I wonder why it is so hard to discover the basic facts about BMW's default mode for the car.

Richard
 

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A lot of users actually claim that milage CAN be better in P500 than it is in P400 - of course you have to keep your foot out of it or it will be worse. I can't say from firsthand experience that milage is any better in P500, but I can say that as long as I drive reasonably it's no worse.

I don't believe that P400 mode was created to save fuel though; it MAY be related to emissions in the US. I believe I have read somewhere that there is more valve overlap in P400 which would decrease emissions. I can say from first hand experience that the car is smoother around town in P400, and I'm glad the car has it for those occasions.

I'm also glad for P500 for THOSE occasions as well :M5launch:
 

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P400 definitely fuel saver the other 2 modes is when a 335i pulls up and says lets run em 😂😂😂
 
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