I've had a lot of questions about the auto tranny ralliarts. I have someone who very kindly allowed me to open her ECU and download the rom. I haven't driven an auto and definitely don't want to go beating up on someone elses... Too bad there are no mitsu rental car companies :P

Now, suppose you lock the car in "1" or "2" will you hit the rev limiter or does the car decide to shift for you? Where does it shift if you hold the pedal to the metal? Just before redline or some other place?

How many people actually have auto trans and want to mod them?

-Michael

 

Well I've got a slushbox in my Ralliart, and if it weren't so cost prohibitive I would swap it out to a manual in a heartbeat. But to answer your questions:

If the gear selector is in L, 2, or 3 it will wind out the approiate gear then just bounce off the rev limiter until you shift it yourself or let off the gas. The rev limiter kicks in at 6500ish on the auto tranny.

With the pedal to the floor it will wind out to 6500ish before shifting, but I'm not sure if the tranny is just shifting that way because of how I drive (with the INVECS-II learning driving patterns and all)

Hope that helps!

 

that pretty much sums it up, also if ur driving like a granny it'll shift at about 2500-3000rpm

 

The transmission control stuff is very complicated. Just for the AT it's almost as much data as the entire rom. I can try adjusting the rev limit and see if the shift points are calculated based on the rev limiter or their own setting. I suspect it is the latter because they probably don't want the auto to bounce on the rev limiter every time. Some testing may be necessary...

-Michael

 

Wow, sounds like you've got your work cut out for ya. Is there anything worthwhile to change in the code for the AT? I've got no clue on how it's scripted, is it like a table that corresponds to rpm and throttle position to select the correct gear? I don't have a lot of experience in programming, I've just dabbled in some Visual Basic and C++, but what language is the ROM written in? Sorry for all the questions, I'm just curious as to how the brains of the RA work. Thanks!

 

My automatic Ralliart is an 04 and the rev limiter is around 7k. Not positive where but just letting you know it is definately not 6500.

 

Shifts exactly at 6500 when the pedal is floored by the way... Unless it is wet and spins past that. Mine does at least.

 

I suspect your tach is just reading a little wrong. Not at all uncommon, about 90% of the hondas I tune on a daily basis read from 500-1000 RPM high near the rev limit. The true test would be to watch it with an OBD2 scanner.

-Michael

 

The rom is in assembly language. They used a proprietary processor and I had to put a lot of $$$ down to get the proper specs. The machine code is similar to some existing processor archetectures but there are a large number of instructions that are not. I know it's originally written in C but I'm not 100% sure which compiler they used, I have my guesses but it's much too expensive for me to buy.

-Michael

 

Didn't realise that about the tach. That is interesting info. Thanks

 

Not sure if you have had the chance to look over the code for the AT in more detail yet, but I was curious if the possibility was there to create an electronic "shift kit" of sorts by changing the instructions that deal with shift overlap and such. And if it is possible, can the shifting behavior be modified for things like throttle position? eg: Having quick, crisp shifts in a WOT or high throttle situation while allowing smoother shifts for normal driving. Just a though... I'm sure the auto folks would love to have something like that. I know I sure would.

 

i would sooo love better shifts at wot. haha

btw, im not sure what rpms it shifts at when i put the pedal to the floor, but i do know its a bit past redline.

 

~6750 rpms is where the rev limiter is, so thats more than likely where its gonna shift.

 

Yes, an electronic shift kit is exactly what can be done by adjusting the spool solenoid duty cycle. I'm not an auto tranny expert though. I would need a tester to come up with the necessary changes.

For the shifting thing it's more likely that it has its own table to control the shifts rather than reverse calculating it from the engine rev limiter as the code to control each is fairly separate. I would have to try it.

-Michael