I know no one here knows me, but I've been around tuning cars myself since 96. Mostly speed density, but I've done some maf tuning as well, in the nissan world.

In the nissan world, when we program the ecu, its pretty much dependant on two factors: which maf is used, and what injector size. So long as those two remain the same, if airflow is changed, the ecu does not need a retune for the most part. Nissan computers just use a mathmatical equation to arrive at air/fuel ratio, so you basically tune for afr. Once you discover what number to input in the program, its 1 part air = x multiplier of fuel.

Here in the mitsu world, it seems like you have specific flashes for specific combo's, and on top of that, if something is changed, say going from a K&N to a Buschar full intake, a reflash is a neccesity.

I was wondering if Al could explain why this would be needed, not specifically in that case, but in general.

There's a question in there, I think

 

bump for tech Q

 

certainly you know, dont you?

 

why does this go unanswered... such a simple question that i've not found answered anywhere

 

You only need a flash to maximize your add-ons and to ensure the car is running healthy. You could upgrade without flashing and not every upgrade alone needs a flash but flashing is just another term for reprogramming.
Here's an example.
I am currently at a standstill on my 300ZX because I bought a Dinan chip that they no longer support. If I change cams or intake or injectors or exhaust, my current map won't balance the a/f or timing correctly. I could buy a JWT chip but the same goes there, every time you do an upgrade you need a retune. Mitsu is no different.
Are you saying you take your 240 and add new parts and don't retune? Of course you do and the same goes here.

 

on my nissan, and if yours was tuned properly, i would not have to tune for A/F unless I change maf or injector/fuel pressure. Reason being, you can easily program a/f, as it works as a multiplier. For example, if you tune the ecu for 12:0 a/f on the dyno at 10psi, then program the rest of the map with that same multiplier, you can raise the boost to 20psi and run the same a/f (assuming you are within the limits of your fuel system). You simply move to a different load point in the map. You can add cams, intake manifolds, etc, you can do all sorts of stuff that seriously changes the VE and the a/f will be the same. Also, if the tuner is worth a damn, he will scale down the ignition timing as the load levels increase. I realize that custom tuning each and every change would yield slightly more power in regards to ign timing, but a/f should not change. This is in the Nissan world.

what I want to know is, what in the software/maf/etc makes the EVO ecu different. I could understand if we were talking speed density, but since we're not...

If you need a custom ecu tune done in a reasonable amount of time/price, I highly recommend Harry at www.ztuner.com. I actually worked with him a lot in helping to develop his ecu tunes back when I used to own my shop w/dyno.

 

Thanks for your inquires. I am actually working on a technical manual in which I detail and outline exactly how the factory evo ecu functions and how we go about tuning them and how our equipment works and how to go about tuning a evo. Basically, anyone who reads this new book will know everything I know about how ecus work and all my competitor tuners will be able to duplicate all my work without having to take the time to figure it all out theselves.

I will be posting on here details on how to purchase the book once it is published.

Thanks again for your questions.