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      02-24-2011, 11:40 AM   #30
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roninsoldier83's Avatar

Drives: E90 BMW 335xi N54 6MT
Join Date: Oct 2010
Location: Denver, CO

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Originally Posted by tscdennab View Post
This is just another disguised tuner bash. For whom may be interested, I have done some testing on a private road a few days ago with a friend's car which has a JB4 (he used Map 7). I have GIAC Stage 2.

The ignition timing was almost identical between my GIAC Stage 2 pump and his JB4 map 7. We compared the excel files in detail after the runs, we did graphs. Nevertheless he beat me but I have fewer mods I will ask for his permission to post some of the graphs.

Conclusion: the N54 ECU is not a Subaru ECU: it is more advanced. The knock sensors and knock ADAPTATION work very closely to ensure proper timing. At least from what I have seen, and I have seen hard data with back to back runs, not just talking and bashing.
I'm just sharing my experiences, was not intended as a "tuner bash", but I suppose I can't help how you take it.

Originally Posted by tscdennab View Post
In fact, it's the other way around. Subarus have predefined maps which means they make the same power even when the conditions vary (to a certain degree, of course). N54 is more dynamic and calculates many of the values "on the fly", whereas other ECUs have predefined values. That's why some days you feel the car a bit slow, some days you feel it is a beast.
No offense, but you might be a little bit outside of your knowledge base here... from what I understand, the fueling on the N54 is closed loop (WBO2 sensors from the factory FTW!! Many cars only have narrow-band O2's and can't see actual AFR outside of a small range), but just like any other modern turbo car, there are timing tables that calculate base timing in regards to load.

Subaru's actually do have compensation tables for temperature, barometric pressure (helps with elevation), knock, ect. Technically, they have what is referred to a IAM (Ignition Advance Multiplier), which is a fairly simple algorithm that when knock is sensed at XX rpm under XX load, it lowers timing (initial value of 1, shows fractional/decimal value when unable to reach peak/base timing value), and as you go through cycles, it will slowly attempt to ramp timing timing back up to base initial value. Basically, it keeps track of historic knock at various load sites, and attempts to advance timing slowly... it's remarkably similar to the autotuning feature (except with timing only, vs. boost) this community is used to, except stock.

It's kind of funny, years ago, Shiv found a way to "trick" their ECU's into raising the IAM value to its maximum in a matter of seconds haha:

Either way, in certain aspects I would agree with you, this ECU/DME is faster, able to react more quickly to knock and fueling is fully closed loop (awesome!), but when it comes to timing, I respectfully disagree, as Subaru's & EVO's employ learning curves (again, similar to autotuning in regards to timing) that keep track of historic knock and calculate accordingly.
Current- 2015 Subaru WRX

Former- E90 BMW 335xi 6MT N54 - SOLD

Last edited by roninsoldier83; 02-24-2011 at 02:20 PM.