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      02-24-2011, 09:50 PM   #89
Lieutenant Colonel

Drives: pickemuptruck
Join Date: Jul 2009
Location: Phoenix, AZ

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Originally Posted by roninsoldier83 View Post
I think I understand your question... and if I do, yes, tuning is fairly "linear" per se. For instance, if two of your set points for example are 3000rpm and 3500rpm, and in the same load column, at 3000rpm under XXX load, you have a value of 14.5 degrees of timing, and then under the same load value at 3500rpm you have a timing value of 15.5 degrees, the ECU will "ramp" to that value per se. In other words, even though you do not have a set point at 3250rpm, at that RPM under the same load, the ECU will calculate your timing value to about 15.0 degrees. Does that make sense/answer your question?

It will work the same way when sliding between load values at a fixed RPM. A 3D image is a bit easier to understand, as it really does create a "map".

I've never played with Vanos, but I have played with AVCS and MIVEC (cam timing), and they have their own separate tables/separate from ignition timing tables. Honestly, I never invested too much time into cam/valve timing parameters, as I found that you can usually find a bit of lowend torque playing with them/decrease spool time just a bit, but for the most part I found most of them were pretty well tuned from the factory.

Haven't played with too many Honda's (very minor experience with some of the Hondata software), but VTEC typically has its own set point (separate adjustable parameter) that most people adjust at a set RPM. VTEC is just a simple extra lobe/rocker arm that adjusts lift/duration at a set point:

If/when the extra lift and duration increases load on the engine, the ignition timing map/table will be consulted in order to attempt to target the correct amount of timing advance.

I hope that helps.
Playing with the tables would be neat... the most i've done is set a distributor back in the day.

For the vanos, you can see the timing adjustment in the tables ramping up and then down from 3500 to 4500 due to the different cam durations.

I guess what i was asking was more if there's a direct relationship, so if a hand full of boxes are determined on the dyno or by ear, you can fill in the rest.

Originally Posted by ExpensiveTaste View Post
I understand what the OP is saying in every way and I agree 100%. However, I think there is more to it. Can someone conduct a test when it gets warmer out? Run Map 0 or whatever map reverts to the factory BMW tuning and run 87 octane from an empty tank. It's obvious that there will be knock and the timing will drop down by 3 degrees every time. HOWEVER...I would like to see how long it takes for the ECU to adapt and go back to the normal timing changes of less than 1 degree plus or minus. Also, once it gets there, will it stay there without raising timing back up and then getting back to 3 degree timing drops again. We need to figure out the logic the ECU uses to control adaptive timing. For example, does the ECU only try to adapt back up after x successful small timing advances? Is this WOT adaptation a separate logic, or does cruising conditions affect it as well. I would like to learn more about the ECU logic as I'm sure most of us do...
Plenty have done this, but using race gas instead of WOT on 87... OUCH. The dme tries to get back to its curve fairly aggresively. you can see the slope is much greater in most JB logs because there's no correction.