von Racing » 22. Nov 2007, 12:18
I´d have to go on record here and say that there´s a LOT more to this than meets the eye and it´s anything but simple.
Getting a car to deliver on full throttle is one thing...getting it to be well behaved is another-which in turn takes a LOT more work and understanding.
Hardparts of a stand alone is the easy bit.
VEMS vs MS.
Mainly the processor of the VEMS is way more capable than any current MSs.
Yes,they both share the same software foundation,but that´s it..and the two softwares DO NOT interchange.
Ie,DO NOT try to use the VEMS software on the MS as it will only ruin the unit.
When it comes to a stand alone..there´s a few points that need to be met that most people don´t get into in my book.
1/Processor speed/repeatability
System HAS to be set in such a way that it repeats its behaviour time after time after time...otherwise there´s no reason in even trying to MAP the system.
Hard part here is the intake air temp,because as it varies with driving conditions and outer temps as well as underhood temps..so will gas mass entering the engine..
Now..this is a little of damned if you do and damned if you don´t,cause no matter where in the intake tract you end up putting the IAT sensor..you WILL lose at some end.
What the VEMS group did was in my opinion a masterpiece,cause they basicaly let the IAT sensor end up wherever...and let the wideband lambda sensor take control of the varying conditions that WILL be an effect as the engine is run.
Further,you can control the working parameter of the lambda to YOUR liking/needs.
Now,of course this sets GREAT demands on WB calibration...none the less it´s THE most thought through setup i can imagine.
Be adviced tho..it is more or less "standard" that the WB sensor needs to be recalibrated from time to time..
Further.
The MS was an offspin by Bowling and Grippo from the DIY-EFI board mailing list originating back in the 90s at one time.
B&G decided to keep the setup what´s known as open source,meaning anyone could contribute.
At the time..that was a masterpiece as development of the MS took on a downright redicolous speed.
However..i seriously doubt that B&G ever anticipated that the MS would strike home as it did,and it still being open source THESE days brings that there´s WAY WAY WAY to many chef´s involved leaving us with a setup where there´s a will and saying for everything in sight.
Now..the VEMS(which started as the MS AVR at one time) was a group of the MS crowd that got tired with all the "amatuer" involvment.
Hence..VEMS is still to a degree open source,but..in the form of a "think trust".
This means..that to this day you´re still welcome to contribute to the VEMS..however you have to write the "think trust" who will decide if you´re into the loop enough to be of any value.
A smart move if you ask me as i brings that all the "moronic" ideas are left behind and only people that really knows what it´s all about get in on the work.
I´ve given the VEMS crowd critisism for that they release new software versions to often still.
Point being that the customers of VEMS systems that are NOT interested in becoming "experts" of SAs only get confused by the array of software versions available.
As a tuner...i´ve got an interest in the software improvments that brings PRACTICAL advantages...and the truth of the matter is that most don´t.
..and at the other end...there´s guys like me...having to answer phone calls from customers that want the "latest" software installed as it HAS to be better as it´s got a higher software number.
Just take the later software versions for the Audi 5 cylinders.
I´ve had customers call me up to tell me they NEED the latest 1.01X version...where i have to spend another 30 minutes explaining to them that the version they ask for can not even be installed on their motor and get it running!!!!
So..i´ve asked the VEMS group to keep that stuff under wraps as most don´t have a need for the latest versions.
To go on...minor development in for instance Launch control resolution will render a new software...and what good is that version for someone running a naturaly aspirated engine OR a turbo engine that isn´t to be used for dragracing?
I think you see my point...
Further..i sincerly WISH that all those attempting this themselves would do us all a favour and install a Hall effects trigger first thing they do.
Yes...VRs can be used,but it is such a MASSIVE job to get right that i´d say that 99% of those installing a SA have no idea what it takes.
Idea for most after all is a running ENGINE...not to spend 100man hrs running around like one legged chicken trying to find out why they have HC values through the roof at 3000rpms and 70kpa pressure.
VRs are EXTREMELY hard to get 100% right.
Take my word for it,and to even THINK about opening ones mouth on the subject you NEED a hardcore exhaust analyzer.