new firmware releases

[Sprocket]

I thought that OEM idle control was replicated in VEMS with ignition control and IAC

Forgive me if I am being blunt, but what else do you need? the IAC valve should be set such that, at idle, air can still be removed (roughly 40 steps if its a stepper). Throttle stop should be adjusted to give you your desired idle with the desired idle advance. Idle ignition thresholds set to +-5. I have never had a problem. idle PID set up however, is a tuners nightmare, as there is little explanation of what P is which means you are changing numbers to get the results, without really knowing whats going on.

I can get my engine to start and idle at 1250rpm when cold, ramping down to 850rpm when warm and controls well at 850rpm once I have tuned PID. Afterstart I see another 200rpm ramp down over 3 seconds, Turn on all the lights, wipers and rear screen heater, and the idle control sees the change in engine load and brings the rpm back up again. It replicates that which was the OEM ECU.

Now if this is not enough what else is there? Perhaps modern (read that as within the last 10 years) OEM systems work some other magic, but what you have to really consider is that you will never ever be able to control an engine anywhere near as well as ANY OEM ECU unless you buy a high end Motec or similar, even then im not sure it would be as good.

A cold start ignition map would be more important, and in recent firmwares there has been an effort to get something like.

I have had experience of Emerald, Motec and Specialist Components ECUs and im not sure i have seen an 'idle advance' map, they do have simple cold start advance maps.

[GintsK]

I am pretty satisfied with current idle strategy. I just try to describe what most probably cause idling problems.

I suggest separate idle advance from main map. One value! Triggered by speed and TPS. With some advance changing rate limitation.   And not because of idle:
 Best idle quality usually is 5...15deg. But cruising area in map is very close on some engines and it often requires more than 30deg. So this is conflict. It hurts driveability a lot when advance jumps. My spark tables sacrifices one of both. Or are compromise between both.

[AVP]

sprocket----> did i understand correctly? you have an idle of 850rpm and once you turn on all electrics and hence get a voltage drop, the idle goes up?? how do you do that? Usually on voltage drops or when the AC kicks in the idle speed drops! it doesnt go up! the PID configuration may keep it in place to a large extent so as it doesnt stall, but i have never heard that with all electrics on the idle goes to higher level...

can you share any info on this and on which firmware you have this setup?

[Sprocket]

when the engine load increases with all the auxilary equipment turned on, the rpm will drop, obviously. As the idle ignition control adds 5 degrees in an effort to raise the engine speed, this reaches the threshold for activating IAC. the IAC adds a little more air, the engine speed rises, and ignition advance drops back within the threshold and remains there until engine load is removed. The opposite then occurs.

I set the max advance and max retard to 6 degrees and then threshold for activating IAC to 5 degrees.

works the exact same as my OEM ECU

[mattias]

I am pretty satisfied with current idle strategy. I just try to describe what most probably cause idling problems.

I suggest separate idle advance from main map. One value! Triggered by speed and TPS. With some advance changing rate limitation.   And not because of idle:
 Best idle quality usually is 5...15deg. But cruising area in map is very close on some engines and it often requires more than 30deg. So this is conflict. It hurts driveability a lot when advance jumps. My spark tables sacrifices one of both. Or are compromise between both.

I think you just wrote exactly what I'm thinking. It's one of the things I wish to be implemented, we have a back-log of more important issues to deal with first but I do think this will be added sooner or later.

I've seen this problem clearly when cruising around with large displacement engines and manual gearbox, BMW 3.5 litre and any larger V8 engine will have this problem. If you have a bit more radical cam profile it will definately be a problem too because you idle at a much higher rpm to keep the engine smooth and oil film intact on critical valve train components.

[AVP]

well at least its a thought of implementation so that is good!