Rotax 915iS injection parameters

That secrecy is one of my misgivings about the iS engines. I wish they were more open about how the ECU works but just because it is digital they keep it secret with multiple BUDS access levels and I think that does more harm than it does good. Even information about error codes is hard to come by! Or like lanes A and B get different inputs and aren't exact twins which is very confusing.

I learn a lot from your posts when you figure things out about the engines that are not in the manuals and I am very greatful for that!

The Probem is this.....

If you allow end users to change fundamental parameters.....they will. The are "well intentioned" but have a serious talk to R&D and maintenance depts of any major engine manfacturer and they will tell you that  99.9% of these changes are detrimental to the engine.

If Paul has a unique use case he should approach Rotax directy and see if they will help.

I was involved in three engine developments where the Manu ECU was swaped out and an open one like the Autronic put in and the engine redone. This took months on a good Dyno and there were no real "gains" we did however solve a few areas for a unique use case.

Rotax is not being secretive, a Company or Country with the right resourses can reverse engineer anything. #B29 #Russa TU-4.

However Rotax is definitely protecting us all from our own arrogance...

Glenn Martin wrote:

The Probem is this.....

If you allow end users to change fundamental parameters.....they will. The are "well intentioned" but have a serious talk to R&D and maintenance depts of any major engine manfacturer and they will tell you that  99.9% of these changes are detrimental to the engine.

If Paul has a unique use case he should approach Rotax directy and see if they will help.

I was involved in three engine developments where the Manu ECU was swaped out and an open one like the Autronic put in and the engine redone. This took months on a good Dyno and there were no real "gains" we did however solve a few areas for a unique use case.

Rotax is not being secretive, a Company or Country with the right resourses can reverse engineer anything. #B29 #Russa TU-4.

However Rotax is definitely protecting us all from our own arrogance...

I half agree. Average arrogant end users wouldn't know how to do it if it needs specialized software and understanding like knowing assembler language to modify firmware. I never said they should make it easy but I don't think they should try to make it impossible.

If someone truly knows how to do it and is experienced then I don't think they should be prevented. If I want to enable the knock sensor and make it advance spark timing or change mixture or at least turn on the lane light why should I be prevented from doing that if I understand how?

I agree it would be a bad idea to open up parameters to be modified easily for someone who doesn't understand it like through a simple BUDS button or settings on an EFIS. How many people actually damage their carb engines by changing fundamental parts of the engine like displacement or compression ratio or mag timing just "because they can"? It is easier to change those than it is to read datasheets and programming guides and knowing how to reflash firmware and actually doing it so in a sense the EFI engines are harder to customize (or analyze) than the carb engines and that's what I disagree with.

Also I think we are kind of talking about two different things here. There is transparency and there is customizability. Rotax could publish a detailed document of their ECU workings and behavior, inter ECU communication etc without giving people the secret key needed to do modifications. That is what I had meant when I said secrecy and why I appreciate Bill's detailed posts that help me learn more about how the engine works.

Disclaimer: The views and opinions expressed in this post are those of the author and do not necessarily reflect the official policy or position of ROTAX!

Two Cents Worth: I suspect that 'the secrecy' might simply be that their hands are tied due to potential product liability.

Remember, it seems that ROTAX prefers not to provide the logfile reader to anyone who hasn't passed the iRMT training for the iS engines. 

Why? Possibly because taking an incorrect 'corrective action' based on a naive diagnosis may be more dangerous than an AOG due to no diagnosis. The iS is a fairly complex system and there are a lot of different parameters recorded in BUDS logs  - and how many of them may be interactive? Methinks that it is not so easy to make the right diagnosis - but potentially extremely easy to miss something and make the wrong one.