I know it's probably not that applicable to the Evo in any way but how feasible is it to add an Alpha N table to one of the SD roms?

I have a 1.6L 4g92 mivec which uses MAP and am sorting out the wiring to get it running on the Evo 8 ecu on the Evo MAF then getting someone to do an SD conversion tune for me.

I would eventually like to run some ITB's but that's damn near impossible to drive on the road with just MAP based fueling from what i am lead to understand. Hainvg Alpha N at idle areas and the rest MAP based would be advantageous.

Or i could stop being "frugal" and just get an AEM

 

Alpha N?

 

Alpha N is a way the car calculates how much fuel is needed using TPS and RPM. No MAP sensor or MAF. Some cars have it from the factory in case a sensor fails so you can get home. I've messed with it on my old DSM using megasquirt...

 

The 97-01 mirage with the 4g15 uses speed density natively and has a small alpha n map. Unfortunately that engine uses a distributor so the ecu itself is of no use to me.

Can the rom/xml for the 4g15 at least provide some insight to someone who know's what they are looking at to see if implementing it on the evo 8 ecu is possible?

 

All Mitsubishi ROMs that use a Karman Vortex MAF have an Alpha-N map in the code.

 

The tiny 'limp-home' map?

 

thats the one. pretty basic but it works - just. If you do a lot of logging you can set more accurate values into the map, especially if you have changed injectors.

 

thank you!

I will see what i can find xml wise for the 96530006

I guess the hard part now is having the ecu use that map say below 2000rpm

 

How does it determine ign timing if the alpha n map does fuel, and no maf or map is used?

 

Add this to your XML for the 9653 .

 

It does just fuel. Alpha N sucks for anything but idle really, it can't compensate for load changes, comparing 50% tps on a flat road to 50% tps going up a 6% grade incline, the load placed on the motor will be vastly different but it will only give as much fuel as in the map regardless of load. (if that makes sense)

THANK YOU!

The car is running SD right now as the MAF proved too much of a pain in the *** to re-scale (like trying to use a 7bar map sensor to tune an NA car....no resolution). So far the tuner has part throttle and all the driveability areas of the map done, we are working on the higher load areas and WOT currently. This is on the stock intake manifold and throttle body setup.

If there are any dis-assembly guru's that would be able to at least let me know if I am barking up the wrong tree?

IF a patch could be made to use the limp home map for 0-1500rpm and then switch back to the SD would using the limp home map affect anything else? I ASSUME it would use the low oct ignition map (which to be honest is fine) but I have no clue what other electro jiggery pokery would happen.

 

Well, the limp map is active when the MAF is unplugged, so if you had a relay or RPM switch that would disengage/engage the MAF/MAP at a particular time, it could work. Not really a great way of doing it, but, it would be an option if code mods weren't available.

 

My thoughts on that table are that the units contained within it are not for fuel, but are actual load points based on TPS and RPM. X rpm & X tps = X load.

That way, it would still be using the main fuel/ign maps, but be extremely limited. More than likely the low-octane ones.

 

Only thing I see with this is once the ecu doesn't see the signal and switches to limp home, it likely won't revert back till next key cycle.

 

That's entirely possible. I wonder if disabling the CEL test routine would help?

It is just an idea off the top of my head, since patching is a bit beyond me right now, lol.

If you change the scaling of the data units in the Limp Home table to "load8", it makes more sense .