Aftermarket ECU what motronic functions are lost?

[Jamo]

I know the gains of an aftermarket ecu but what specific standard motronics functions are lost when swapping?

carbon cannister
trip computer functions

what else

[GazzaG60]

depends what ecu you go for.

the trip cvomputer mpg etc is not accurate once you change fuel pressure, injectors etc anyway so that has to be negligable. most carbon cans would have been useless around 5 years ago anyway.

from what i have done. the easiest is vems. you lose the MFA like you say but it does always say 200mpg so its not all bad lol. i have currentyl no cruise but thats due to the wagner and i didn't refit the carbon can after fitting the wagner either.

the rest depends of the feature set of the ECU. the first one i used was a linkplus designed for subarus around 1993 by a rally driver called possum bourne. that was very basic. all table based with little control of anything. even things like required fuel in PW ms is not the norm. vems adn megasquirt are very similar in control. megasquirt is cheap but works and can do anything if you have the skills around the cpu. the last none vems i did was a link G3 with a full harness. my mate fitted it and i tuned it. it was a bit of a pig to map. lots of room to make changes and a nice feature was you could just add a new column to the map at any point and it would scale. handy when tuning bigger injectors for cruise. having said that it took quite a few hours to get a good setup. not seen the car in a while but belive its still strong and terrorising stoke.

i know this doesn't really answer your question but i think its necessary to be more direct and say will i lose xxx if i go with xxx ecu

[Rocco]

new projects in your car Mr Jamo??

[Jamo]

No covering all basis, Gazza thanks but doesn't really answer the question inhand, all after market ecu's are the same really bar knocking sensing ability.

I'm interested in what features are specific to the motronics ecu and the S2 which can't be replicated

[A80Avant]

my guess is that even the fuel consumption at some point can be made to work since there are always open ports on the ecu for further features.

Carbon canister in mine i still on the car,not sure if it works or not though,I will ask marc about this.

i may have understood wrong, but cruise control is independed from the ECU and still works on aftermarket ecu

[pnanassy]

knock control is possible with this(+ an Mseries ECU):

http://www.motec.com.au/skm/skmoverview/

it will also log fuel consumption,and the free outputs can be used every imaginable ways.

it has no limp home maps tough...(how well are the limphome maps mapped on a well tuned motronic?)

It would be great if you list the "functions" you are looking for...

hth

[Jamo]

I'm not looking for anything the idea of this thread is a heads up you'll lose this if you change your ecu if you see what I mean?

[pnanassy]

Change to what ECU?
There is a wide range of aftermarket ECUs,which you simply cannot compare to other.
With one you will loose almost everything,and you will be happy if it starts at all,with others you will not see any difference,especially if you are after good tunability,special race functions,etc...

Sorry, but i do not really understand the idea.yet.but im trying

[Jamo]

Lets make it simple and clear for those that can't grasp it, if you've installed an aftermarket ecu what have you lost that you had on motronics

[GazzaG60]

it is simple jamo im with peter. its not clear cut.

there is potential to lose nothing or lots of things. whether they are important to you mepends on what you want.

for example i got asked yesterday about vems MAT compensation and how its adjusted. not on pectel im sure its a table of some sort thats changable. Jogi had issues with AIT (MAT in VEMS) compensation as potentially his engines problem. in vems its fixed at present to my knowledge until a further firmware release. its not an easy scietific thing mat compensation so a fixed general rule is there.

the things you can see you have lost are not always the most relevent.

[johne]

I know the gains of an aftermarket ecu but what specific standard motronics functions are lost when swapping?

carbon cannister
trip computer functions

what else

Immobiliser?

Rock solid reliability

[A80Avant]

immobiliser?

most of he aftermarket alarm systems take car of that.

MAT compensation at the moment in VEMS is a set curve which is easy to know how to tune it.On the next firmware it will be manual and be able to add/substract degrees depending on IAT(MAT).

[repo]

With proper engine management You loose only the computer functions.

Who needs carbon canister and for what?

All aftermarket ecus can do the same powerwise. Tuning flat out is easy. Mapping the cold starts and very little load maps, like needed on parking lots is the tricky part. Especially if the weather (environment) compensations are no up to the task.

For more You have environment compensations in the ecu, the better overall behaviour You can get - yet more complicated it is to achieve.

I do not know any aftermarket ecu, that had limp mode. Certain ecus have variable, so You can set some basic value for ecu to use, if sensor failure occurs. Usually You still can make the same feature with compensation maps, if You know what You are doing.

e: Im my point of view, every standalone owner should learn themselves to tweak the basic maps. It is impossible for tuner to set the cold start enrichment correct for -10 celsius on dyno on 20 degree summer day. This is something that needs to be done while the situation on is on, iow on cold morning.

[pnanassy]

The Autronic SM4 for example has a function called limphome.It does what Repo says.
In Motec V3 you can setup "Default" values on all input channels,so it may be still driveable even with a broken/disconnected/faulty sensor.With some wise values engine can be saved if something goes wrong.It will also light up a CEL.

Not sure what the Motronics limphome function is,can you please explain it?What event will trigger it,which maps will be effected?

[GazzaG60]

gotta agree with the 2 above posts.
for every hour on WOT tuning there's 10 on startup, post start and cruise.