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      02-24-2011, 12:42 PM   #37
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Drives: e92 335 - gone // e36 M3 turbo
Join Date: Mar 2007
Location: Ellicott City, MD

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Originally Posted by roninsoldier83 View Post
Fueling is closed loop on these cars compared to open loop on most other cars thanks to employing x2 WB02 sensors from the factory and having an ECU smart enough to address AFR quickly. However, there are still timing tables for these cars with base values that should be determined by load, just like any other modern turbo car (well, most NA cars as well).

Maybe there was a misunderstanding (we're on an open forum, it happens ), but I agree the base timing map (unless altered) is set by BMW from the factory. Sorry, I thought it was implied.

IMO, the knock sensor is meant to be a failsafe, and under the wrong circumstances it is a crucial tool in saving your motor. However, rather than relying on it as a means to altering timing, the base timing values should be set as a maximum, which should be under the knock threshold. Ultimately, the goal when tuning should be be set timing values (as well as AFR & boost of course) to a value that allows WOT operation without knock under most normal conditions.

^^^ Apparently you beat me to it


While you and I see to have different styles of communication, on a technical level, we seem to have a similar mindset.

I've seen numerous OTS maps for multiple cars... I'm not a big fan, as they typically leave much to be desired. Hell, I'm not even a big fan of many supposedly conservative factory tunes (I've seen some pretty atrocious logs on stock cars of various makes over the years!! We're talking LTFT's around ~15%, AFR's deep into the 9:1 range under WOT, knock/timing correction all over, cars that won't hit peak targeted boost, you name it). Ultimately, these maps are made/tuned by someone else in another part of the country, and like humans, among cars there will always be variances. Manufacturers try to be overly conservative and make maps that will be safe in a variety of conditions, but there are so many variables from car to car that this is rarely optimum. I've seen cars with the same mods, running the same OTS maps, under the same conditions (elevation, fuel grade ect) make WOT pulls, and the logs/torque curves are vastly different.

Personally, I would rather tune my own car, for my own conditions (fuel grade, elevation, variances specific to my vehicle, ect, preferably under harsh conditions..) to ensure that my car is knock free while pushing peak boost/timing/under full load. I'm a big fan of optimum performance, consistency and safety when at all possible
That's just my $.02 though, YMMV.


If your riding the knock sensors 24/7 this simply isnt possible.

I had my car custom dyno tuned last summer (which didnt work at all thanks to a clogged cat that I only discovered a few weeks ago ). A few other car geeks were there and all were bummed that it was close to 110f in the shop since we wouldnt see huge #'s being thrown down.

I on the other hand was happy with the heat, it meant that my custom tune would have the ability to be safe even in the worst conditions the car will ever see.

I want a safe and reliable tune that is not tuned to max power at all times, if you run an engine at 99.9% all the time and let the knock sensors pull timing back everytime you floor it, you ARE causing undue stress on your engine.

There is no arguing that fact.