TPS Acceleration Enrichment - err WTF
 

Hello,

So a few times I have seen this in the manual:
https://img31.imageshack.us/img31/46...jectionwtf.png

and i've always lol'd... (at the bottom half)

I mean seriously, who injects fuel at "random" points in the crank cycle... I thought it was a JP->EN translation snafu.. (Please put up your theories as to why Mitsu are doing this)

anyways, now i'm not so sure... I found some disturbing code, that isn't injector scaled.. (mean that for us 2150 cc fools, we are literally pouring fuel onto the backs of valves :P :P

Anyways, being awesome I thought I would post up some tune-ables:
53040010:
52680022:
I might post up some other XML's, but hopefully some of you can digg em out for me/you :) :)

Anyways the general idea, and I havn't tested this would be that you just modify that last map. Tomorrow I intend to divide it by 4, (600 -> 2150 is about 4x)... oh and then add 30% for E85, since I run that...

Also keep in mind that, as per usual, the ECU is a bit more complicated than just these 4 tables, a lot of control logic is taking place, so sometimes this code isn't even hit (ie its really only used for LOW -> MID TPS transitions, and not MID -> HIGH..)

Anyways peace out (or rock, if your that way inclined :))

Regs
D.

Hey Dave, nice find and yes, random fuel injection if that is what's happening here is odd. Is this code present in pre X roms?

well i guess its not really random, but it doesn't really conform to how fuel is normally injected (ie the first half of that image)

hrmm not sure if its present on CT9A, if you have the manual see if you can find the MFI section, search for "teeth", that should make it a bit easier to find...

Hrmm its called "Asynchronous Fuel Injection"

Still a bit odd if you ask me.

Haltech have some info on it (http://files.haltech.com/downloads/p..._throttle.html) with many of the same tables...

Hmmmm to help with throttle response at low engine speeds.... this would explain a lot of the odd heavy fuel dips I've seen.

curious to see what dividing that table by 4 does for you tephra

I thought fuel was injected between the compression and combustion events? How exactly do we get combustion if fuel goes in "after" spark?

Injecting fuel "randomly" means that more is available when the valve opens again. Kind of like how old carbs worked.

lol you know your dealing with something a little strange when you google for "asynchronous fuel injection" and your own thread comes up in the top10 results..

put up the xml for 52680022...

You're thinking of a direct injection motor. Fuel doesn't get injected into the cylinder in ours, the injectors are in the intake manifold - the fuel goes in with the air when the intake valve opens, not at the moment it's injected. (And it's normally injected earlier, so it has a chance to evaporate)

There is a mention of this in a tuning book I have. It says basically
-during steady state operation a film of liquid fuel builds up on the manifold wall (they call it "tau")
-ECU is aware of this and the fueling calculations take it into account
-When you tip in, the rush of air quickly evaporates the film, resulting in a leaner charge (so extra fuel must be added ON TOP of that required by the additional air, to compensate for the loss of fuel evaporating off the manifold wall)
-The book mentions this can be accomplished by adding to the normal fuel pulse, or via an additional asynchronous pulse.

It's this book: (though that page is not on google)
http://books.google.ca/books?id=Mr-9...gement&f=false

Some more about tau: http://www.ret-monitor.com/articles/852/

More info here: Oddly, this site says the exact opposite from the book, namely that extra injection is needed to offset vaporized fuel that condenses on the manifold walls :/)

http://www.fuelairspark.com/products.../chapter13.htm

yeh ok i understand why there is a requirement for additional fuel at tip in.

i just dont get why its not done during the standard injection cycle

OR if there was some perception of the walls de-wetting, then inject at 360 degrees (ie opposite) of the cycle.. rather than firing all injectors at end of the combustion phase for #1...

OK so sarcasm doesn't come across very well on the internet. Look at the first image and read the first paragraph:
"Fuel injection to each cylinder is done by driving the injector at optimum timing while it is in the exhaust process based on...blah,blah, blah"
What I was trying to say, is that it seem like translation is the issue. Unless there is a massive delay between when the ECU says "fire" and when it actually occurs.

As for "tau" we have tables that already account for this, specifically MAT v MAP.

Yeh normally the injectors are fired mid exhaust stroke so as to optimize the atomisation and evaporation affect..

I'm looking for those tables as well.. I was hoping for a 3d or at least 2d injection angle map, but from what i can tell there isn't one...