1. When the OEM, ECU mapping "learns" (as many call it) because of any new changes to the intake and or exhaust system, there is...NO...actualhexadecimal value changing. All that happens is the existing cruse and acceleration hexcells are chosen from different locations or lines of the EXISTING map as the system works its magic and makes the engine run.
Fact, look it up.

2. Anything freeing up exhaust flow, WILL need more fuel to run...correctly. See item 1 above. To run "correctly" the actual mapping or hexadecimal cells must be "changed", NOT pulled from a different line in the given map.

3. Many people will make changes (mufflers, after cat system, resonator removal, better header, etc.) and the cars ECM will work its magic to "pick" different lines to run the engine from. As noted, NO...hexadecimal values will be magically changed, added to or removed from...period.

4. If you want your engine to run it's best...an engine or chassis dyno or a LOT of experimentation (butt dyno/drag strip) must be used to CHANGE the appropriate hex cells to allow more fuel at specific times, for specific amounts of time.

Again, ECM "learning" as many think happens, is a wishful myth...that just doesn't work like that..!

Mike

 

Correct me if I'm wrong....I always thought that idle and wide open throttle.....the ECM/PCM uses it's programmed mapping for the fuel/timing curves. There is no feedback from the O2 sensor that it uses to adjust anything......it's pretty much "open loop". Now at mid range throttle, and cruising around.......that's when it's in "closed loop" and it was actually adjust the timing/fuel to keep the AFR in the range that's programmed in? Or is it the other way around...idle and WOT are closed loop, and mid range is open loop?

Or do I have all of that wrong?

 

​​​​From my understanding, you have it basically correct, WOT and Cold Idle are open loop, Cruise and Warm Idle are closed loop.
​​​​​The difference with the Siemens coding compared to most is that there will still be some adaptations in Open Loop, most most other mfg coding won't do this.