Engine Management Systems
Pieter, I strongly recommend you jump on amazon or kalahari.net or similar and buy the Haynes book "Engine Management" by Dave Walker. ISBN 1 85960 835 3

Dave is the creator of the Emerald ECU. The book obviously uses his system's screen shots but the principles are universal.

You'll learn more from this than 400 forum replies! Alternatively on the web there are many tutorials; some may require subscription though. Also google Megasquirt, there is tons of info on this system; it's kind of open source like Linux so if you're into hacking around you'd have pile of fun.

And / or jump on PP's site, Dicktator.co.za and Gotech and download their s/w and run it in offline or demo mode on your PC. You can load a sample map so you can fiddle with all the settings and get some feel of what's cutting. Herewith a brief answer to your current, and possibly a few future questions:

1) All ecu's need to know the position of the crank, just like you need to time a dizzy. How you supply these will vary. Most common (and thus cheaper to build a compatble ecu with only 1 or 2 options) is 2 hall effect sensors inside the dizzy, one for areference signal (one "chopper" per dizzy rotor revolution) and one for 4 signals per dizzy revolution. Factory dizzy's supply a wide variety of signals and it's a tall order to ask a guy making a R2K ecu to support all of them! Even the electronics to "listen" to hall effect signal vs an inductive signal differ so again price will affect available options.

2)The ecu must know what your load requirement is, again many options exist, Throttle pos, MAP, MAF (mass Aiflow), either one only in isolation or even combo's of 2 of these or even all 3. Entry level ecu's will ask you to choose one or the other, normally TPS or MAP. Both appear to work fine on a NA motor, MAP of course is essential for turbo motors where TPS will tell the ecu bugger all about boost levels.

3)The ECU will supply an output or outputs to ignition drivers or ignitors. Again, to keep things simple (and costs down) the good old Echlin TP100 is quite universal in entry level ecu's. They are also cheap as chips at Midas. If you have an ECU that will have a setting for a lot of OE ignitors, and their "dizzy" too, you will probably no longer be in the entry level ecu price bracket. E.g. I think the Microtech (or maybe a particular model of it, not sure) will connect to all OE systems in the Nissan 200SX motor which has to have THE most proprietary "dizzy" / CAS setup ever with optical pickups, 2 rows of slots on the wheel, and dozens, if not hundreds of slots in the wheel. The Nissan purists scoff at using only 4!! But you pay for this flexibility as I mentioned before.

4) Then you will start checking out injection mode: sequential (individual) or batch (all at same time) or combo's of both. Entry level will all be batch and in our cars you'd not know the difference. After all when you ran 2 sidedraughts on your Alfa, you couldn't open and close jets in each throttle body per cycle so why start now? If you were building the latest Saab to comply with euro emission standards you may be shopping elsewhere though.

5) On top of all this stuff you can ask the ecu to change things by chosen %'s as temps change. In the simplest terms, this is your automatic choke! Standard in entry level ecu's.

6) At a given rpm you can ask the ecu to throw a contact (output 12v, or ground a pin) to switch something on (or off). This would be your VVT signal mostly, or nitrous, or a hooter, or... Some triggers for this (or a few more independent outputs) might be possible based on a number of factors, maybe using AND / OR logic depending on the ecu. Entry level ecu's used to use rpm but this may have changes.

Hope this helps (a bit).


I thank you in advance of Vanair for the extensive and informative reply=d>

I checked out the book on amazon and cant wait for my old man (Vanair) to order it (a.k.a the credit card holder#-o )

I will definately read and reread all of this and the book as I'm fascinated by E.C.U's

I presume you own the book? does it "teach" one anything about programming or mapping yourself? This is something I'd like to learn to do myself one day but Im a little clueless one where to start looking?](*,)

Always wanted to sit in a car with a laptop plugged into it:-$

Well done on a complete an informative post Bryn, your avaiation background is evident in the manner in which you have supplied pertinant and relevant info which is no doubt valuable to Vanair! Of course there are many factors regarding this subject which would take ages to discuss in its entirity. Obviously my demands of an ECU would possibly be completely different to that of say GregT who is potentialy concerned about economy where as my concerns are more about driveability (Read "Traction") with wild cams and performance. One has to take into consideration what you expect the box to ultimately produce!

I have regularly been told by frontline Motorsport teams that the finest ECU available is the Motec! However, it does come at a price but it does include many many features that "Joe Average" may never need. I personally often wonder what difference the physical components in the unit make in their processing speeds when dealing with high reving engines and for that matter I have also pondered how many engines have been damaged without the owners being aware that the damage has been a result of component breakdown within the ECU, let alone software and finger troubles.

None the less, I have had the pleasure of meeting David Walker personally and I also have his book. I can definately recommend it although as Bryn has said it is geared towards educating the user on his very own Emerald ECU, however, the basic principles are covered. The book also extensively covers carburation and the principles thereof, which in my opinion is vital to first understand well before venturing into mapping! Get the book, it's worth it!
Pieter, go here http://kms.vankronenburg.nl/ and download the manual and start reading meanwhile. They do try quite hard to explain what each option means (unlike some okes who don't supply any more than a wiring diagram), again specific to the options in the s/w but the meanings are generic. They do not give a noddy guide to installation, the wiring diagram is very basic, but with some basic knowledge installation of their kit and 1st startup would a piece of takkie. They have many features and a price tag you probably don't want, but for learning you could do a lot worse. Their s/w also can run in offline mode and they supply a good few sample maps do you can really mess them up no problem.

After proper installation of any ecu you should be a position to get the thing reasonably driveable by using trial and error on a road tune, or using someone else's map from a similar setup. This will get you round the block. Do not give it horns yet, or enter your first race, 'cos...

Then comes the tuning. Without a AFR meter and a rolling road you will be hard pressed to get it spot on. Even with an onboard lambda /AFR display you will find it difficult on public roads to hold a specific load for any length of time before you run out of road.

Installers and tuners do different things! A tuner will assume you have installed it right, i.e. the timing numbers in the timing map concur with real numbers off a strobe light. You need to calibrate the trigger angle yourself or else the timing map will just be numbers, not actual degrees BTDC. If you arrive and your tuner has limited time, he will not relish the idea of fixing your mistakes even if you have lots of cash.

And order the book meanwhile, it's well worth the investment just to get your kop right.

:-s ..... thanks for the info. I am going to get the book and look at the site and manuals.
Ther is a lot to learn and understand but it is slowly coming together.

By the way Bryn I have noticed some comment about aviation ... what are you flying/building ..?

I puddle jumping in a taildragger as well.... big fun!

Just downloaded some manuals and software and will work through that until I get the book.

Thanks again, much appreciated!


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