Optimise the E9x M3

[saxodreng]

Post taken from m3cutters.co.uk - Credits to MaximumBob.

(Shell Vpower in EU is 99 Octane)

Original Thread:
http://forums.m3cutters.co.uk/showthread.php?t=164002




After nearly 9 years of E92 M3 ownership, these are what I think are worth doing to get the best out of a standard car.

1. Update the ECU software if running a pre-summer 2012 version.

ECU software version 240e came out July 2012, this is the last and best ECU version (there were about 10 previous ones).
It offers significant and very noticeable performance benefits over very early software (but less so if your version is say the one before - 231e).
It is also likely to improve reliability.
The performance benefits will only be fully realised in conjunction with high octane fuel.

You can find your current software version by going to a BMW dealer and asking them to print out the data held on your key.
Typically page 2 holds your software integration.



Integration plant is the software version as it left the factory.
I-Level HO is the current loaded version. Mine is E89X-15-11-500
E(8)9X is the platform
15 is the year
11 is the month.

Anything after 07/2012 is ECU version 240e (E89X-12-07-502 or later).
There is a later version (241e) but apparently the ECU data remains the same.



2. Run high octane fuel.

I know this is a contentious issue. Some owners will say that they have run a tank of Shell V-power after using regular unleaded and it didn't feel any different. In fact it may well not have performed any differently. This is because the ECU holds short and long term adaptations that it uses to protect the engine and when you switch from regular to higher octane fuel the ECU seems to be very reluctant to give up the settings it used while running regular fuel
It may require a long run and or more than one tank of Shell V-power before the added performance benefit of higher octane fuel is felt.
Conversely going back to regular fuel will see performance drop quite quickly.
Having found a reliable (Morrisons owned) Shell station selling V-power I only use this station for fill ups.
The difference between my first 2008 E92 M3 on 2009 software and my 2013 E92 M3 on 2015 software when using Shell V-power is dramatic. Its a totally different car.

3. Change the diff oil to the standard Castrol diff oil without FM booster.

I changed mine recently, draining out the BMW oil with extra FM booster and replacing it with Castrol SAF-XJ 75w-140.
The benefits are that the tendency for the less loaded rear wheel to spin up is reduced or eliminated.
A big reduction in the TC light coming on.
Less instability in rear grip under hard acceleration.
In MDM the diff locks up much quicker rather than one wheel spinning up causing the TC to kick in and reduce power.

Diff oil history:
E46 M3:
Factory OEM fill was Castrol SAF-XJ 75w-140
BMW produced their own packaging containing Castrol SAF-XJ 75w-140 with extra FM additives only for customers who complained of noise.
E9x M3:
Same as E46 except (my dealer tells me) sometime around 2010 the BMW Castrol oil with extra FM became the OEM fill.
About the same time Castrol SAF-XJ was rebadged as Castrol Syntrax Limited Slip 75w-140.
Note that the Castrol diff oil above already contains friction modifying additives.
The additives have to allow easy slip between the clutch plates without judder over a large oil temperature range yet lock up completely when clamped together at full operating pressure.
At some tepid temperatures however the additives struggle to allow the clutch plates to slide smoothly over each other and the resulting "slip/stick" effect is heard as a light groan when cornering. This is considered to be a normal function of a high performance LSD. Adding more FM additives to the diff oil (as in the BMW repacked oil) will quieten the diff at the expense of raising the clamping pressure at which the clutch plates are fully locked against each other....IOW the clutch plates slide easier over each other which allows more single wheel spin up and delays the locking action of the Diff when rear tyre grip is lost.
If you do switch to standard Castrol diff oil and find that the diff becomes too noisy (mine is still quiet) then you can either add some concentrated FM (from Opie for instance) or just drain and refill with the BMW oil.

4. Have the suspension aligned at a specialist shop

Pretty much self evident. The before and after difference can be considerable if the alignment is out, especially in the overall stability under hard acceleration and braking.

5. Fit Michelin Pilot Super Sport tyres to the rear.

For some reason these tyres seem to work really well on the back of the car...doesn't seem to matter as much what you put on the front (I have crappy Continental 3s at the moment). The MPSS tyres have plenty of dry grip and nice easy breakaway characteristics. Not much to touch these for street dry weather grip.

[Datka]

Great info. Thanks for sharing.

[Sephiroth]

Not sure i would run mismatched tires but otherwise reasonable