Will unplugging the negative battery cable for.. say... 2 hours clear my Jestr M1 flash?

My guess is no...

I'm assuming the ECU has a "learning" memory that is reset by doing this, but I wouldn't think it would clear my flash... correct???

I'm not trying to clear it, but I'm troubleshooting an idle issue and now that I've had the neg. cable off I'm curious if I have to reflash

 

Disconnecting the ECU plugs for just a few seconds resets fuel trims etc, but power down won't clear the flash.

 

No it won't clear the flash. Temporary things like what was in RAM when the ECU shut down (fuel trims etc.) will go away but the flash itself will be ok.

 

Of course you have a back up of your original ROM, so you can just reflash that back into the ECU. I wonder why you don't want to keep the flash?

MB

 

when you say reset fuel trims, does that mean that it automatically goes to the low octane map?

 

No, the open loop maps will stay the same... the ecu will relearn to make the car run correctly in closed loop and make the rear o2 happy..... If my knowlede thusfar is correct

 

No

the opposite, if the octane number has been decremented due to knock being detected, removing power from the ECU will make the octane number go to 100 and the car will run on the high maps

MB

 

Maybe I can learn something here... because I did not think the ecu kept that long of a record of the knock count, I did some logging and got knock count of 6, which reduced my octane to 99.6 or something....

did some more logging after removing some boost, and the octane was at 100.

So why would you have to reset the ecu to reset the octane level back to 100??

 

In your case what probably happened was that when you removed the boost the knocking stopped (or went under the so called "Safe" threshold). If that happened when the ECU saw the knock consistently decreased the threshold it might simply have re-incremented the octane number over a period of time back to 100 (jcsbanks has a great thread on this if you search around).

Suppose you hadn't changed the boost and had shut off the car. The ECU would have kept that information and on restart the octane number would have stayed in its lowered state (unless the ECU felt confident enough to raise it back).

What burgers22 is saying is that in that case, if you just reset the ECU it would have lost the information that the octane number had ever been lowered and would have reset to its default of 100.

So while it is true you don't have to reset the ECU to get back the octane number back to 100 it is one guaranteed way to make it happen .

 

Hahah, last time I checked the ECU isn't self-aware.

 

When you poke at software all day they take on personalities . I'm sure I have over-simplified above but I believe that's kinda how it works, at least from my understanding (part of which came from that thread I had with MJ and jcs right about the time live tuning was being put on the table).

 

Thanks for the great info!