How does the ecu determine which gear you're in?
 

I've always noticed a few things about the ecu when driving on the freeway. When i'm in 4th gear at cruising speed, it uses ign map #1, but when I shift to 5th at the same speed it uses ign map #2.
also, how does the speed limiter work? I have it set for 75mph (~120kph), but it only works in 3rd/4th gear, in 5th the speed limit bumps up to 85mph.
I speed too much and need a limiter in 5th.

So that was making me wonder, how does he ecu know you're in 5th?
And why does it use different maps for 5th, and which ones are affected.
Is there a "high gear offset" for the speed limiter?
Is there a routine that is changed when in a higher gear? (other than boost)

I have logs demonstrating the conditions. I can't post my rom from my phone...

P.s. AFAIK, the ecu uses maps labeled #1 at WOT...

Its using a gear ratio calculation by RPM and Speed, at least thats what I've been told :D

See that's wierd, cause it seems like there is a switch telling it it's in 5th.
And why does it wait till 85 in 5th to cut me off (about 4000 rpm)

p.s. I know that evoscan uses mph/rpm calc to find the gear...but is there something else in the ecu that does the calc a different way?

The speed limiter in ecuflash is a mis print of the table. It was really used as MrFred found out in some thread here a ratio calculation to determine what gear you're in. If you changed that constant of course its going to act wierd :P.

It's not rlly that weird, when you're going like 60mph and making 3000-4000 rpm, it just knows you're in 5th gear. should you have been in 4th gear going 60mph, you'd make atleast 5000rpm r something

I guess, but it's limited just fine in 3rd/4th. It's like there is another constant offsetting the limiter in 5th. So how do I find it and change it :)

Thread explaining the limiter :P

https://www.evolutionm.net/forums/ec...t-control.html

^lol...I've read through hat thread a few times alreay. Doesn't seem to explain about other stuff like ign/fuel/other tables.

The gear ratio may play some role in the load calculation but I'm not really sure :)

I don't think there is really a speed limiter per say on the evo you can set could be wrong though.

It's all good, thanks for the input. I'm starting to wonder if that rpm crossover might affect other tables, or if each section (ign, fuel, etc) has it's own rpm crossover table.

Oh, and load is the same in all gears as long as you're at the same speed/boost level. Something else I noticed...

Rather than having the ECU actually limit your speed, I think it would be preferable to use a spare ECU output to just flash an LED/sound a buzzer instead, to warn you that you are exceeding your desired speed limit.

I can see some very rare occasions when you might want to exceed a pre-defined speed limit e.g. rushing a friend to hospital, chasing a drunk hit-and-run driver who fled the scene, closed course track event etc.

Not being able to exceed a certain pre-defined speed artificially limited by the ECU doesn't seem ideal to me. I'd rather just have an LED/buzzer telling me I'm being an idiot instead ;-)

^lol, thanks piers... I have the GPS/logger/reflasher to switch maps. If im in a hurry, im sure it wouldnt take too long to flash to my 100oct 30psi map :D