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      02-24-2011, 04:23 PM   #69
roninsoldier83
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Drives: E82 128i 6MT / AP2 Honda S2000
Join Date: Oct 2010
Location: Denver, CO

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Quote:
Originally Posted by Mike@N54Tuning.com View Post
As I said the N54 platform is pretty unique which is why people who come from other backgrounds always have your strong opinions until they do the tuning themselves. Fueling is closed loop during WOT using wideband sensors. Boost is vacuum controlled with a default open position. Timing is closed loop. It uses what we refer to as "maximum set points" and continually adds timing, listens for early knock, and removes timing, until it hits its maximum set point. Which are set so high that it would take race gas to hit them on a stock car. It uses short term trims (knock) and long term trims (octane) analogous to long and short term fuel trims. This is in addition to all the other factors that influence the timing mapping. If you add race gas you will automatically increase advance in a factory stock or tuned car as they are all running on this knock threshold system. As you get close to not being able to support your boost with your octane the DME logic starts overreacting with 3 degree drops instead of small 1/4 degree drops and you know it's time to dial back the boost. This is the basis for piggyback autotuning.

Mike

Ahhh, "maximum set points".... what you just described, is a timing table with "maximum set points" (typically referred to as base timing values) that is based on a load site.

If you need race gas to hit them from the factory (assuming you're correct), that means we're not talking about light load/cruise/idle timing numbers (typically close to the ~40 degree mark on most cars), but actual WOT timing numbers, correct? If there is a timing "limit" that is attainable (with race gas or not), that means there's a table where it is capped somewhere within the DME/ECU, and typically there is going to be a load value associated with this limit... Just my $.02


Honestly, I mean this with no malice, I can't wait for ATR to be released so I can actually take a look into these DME's for myself. How I miss the days of free downloadable tuning software *sigh* haha!!
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2008 Honda S2000 (weekend/former autoX) - 1996 Acura Integra GS-R (occasional autoX) - 2008 BMW 128i 6MT (track/time attack) - 2008 Nissan Xterra (winter beater)
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