Please humor me in my quest for knowledge. I have a evo9 mr. It's my understanding the stock ecu is loaded with 3 maps that the computer cycles through to find the best one for the situation. My question is could you load 3 totally different maps (economy, factory and performance) and have the computer load the correct one for the demand (or lack thereof) at the time? Or is the processing power simply not powerful enough to make those kind of decisions?

 

Where did you get that information? The ACD has 3 settings, but I've never heard of the stock ECU having more than 2 maps, I've also never heard of it cycling maps?

 

I read that in the how to tune an evo thread. An educated guess tells me it has to do with the Mivec tables, engine load, knock counts, rpm, and air temperature.

 

I believe the differences are slight. Probably minimal timing advance and retarded

 

The three maps are most likely interpolated between based upon engine load.

If you were to put load in a measurement of airflow, g/s, lbs/min, etc.

The maps are most likely to do with open/closed loop transition and the amount of airflow.

ie: cruising, mild accell, WOT.

 

The Evo 9 has three sets of high/low octane ignition maps, but only a single set of high/low fuel maps. The differences are barely noticeable between the three.

If you flash the ecu with the Tephra V7 ROM for your car, you'll have access to map switching, which accomplishes exactly what you're after, although it needs to be switched manually.

 

For all intents and purposes, no, there are not three maps. The three timing maps in the stock 88590015 ecu have slight differences but it's not really known when each one is used. There are varying theories, such as being switched between depending on whether MIVEC advance is increasing, decreasing, or stable.

With Tephramod you can have 2 maps. There's not reason to not have both economy and performance from the same map though. The main reasons for using alt maps with Tephramod would be for different fuels, or having a conservative tune for long lapping sessions and one slightly more aggressive for the rest of the time.

 

That makes sense. Seems those computer engineers at mitsu were going for overkill haha