Sequential without a cam sensor idea

[Marek]

If MS3 starts up in semi-sequential mode (i.e. 50%-50% fuelling) and the ECU treats this as a baseline, logging how steady the rpmdot, EGO, map, mapdot are and then it choses to go to either 100%+0% or 0%-100% fuelling (or perhaps 75-25 and 25-75) and then looks at whether rpmdot, EGO, map etc "get better" or "get worse", would the ECU be able to deduce that one of these was the compression stroke and the other not?

kind regards
Marek

[jsmcortina]

I don't think it would be easy to create a general purpose detection algorithm that would actually work.

James

[racingmini_mtl]

That's easy to say in words and for a human brain to understand the idea. But try to put that into an algorithm that can be translated into code and take into consideration all the parameters that can affect the RPM and the other things you mention and you will see that this is far from trivial or obvious. Add to that the need to be generic enough to be compatible with the thousands of different configurations possible with MS3 and this becomes an impossible task.

OEM setups can do this because they have one very specific setup that they can test under all conditions with an army of engineers and huge resources.

In my view, the efforts spent on such a feature would be much better spent on other things. Especially since the addition of a cam sensor is relatively trivial and would result in a much more reliable solution. And if it's not trivial on a specific setup, you need to evaluate if sequential is needed and worth the effort of installing the cam sensor.

Jean

[piledriver]

AFAIK the oem and aftermarket ECUs that support phase discovery use some sort of crank acceleration detecting algorithm
Timing wheel event scatter also used for misfire and supposedly as a secondary knock detection method.

The ecotec setup uses hardware: waveform detection to see which plug of the pair (of a waste spark coil) fired first to determine order
(Short: the ex phase plug is at lower pressure and will fire first)
IIRC the setups used on the older DOHC 4 (name escapes me) and even some DIS systems worked the same way.
http://www.motor.com/article.asp?article_ID=853

A missing tooth cam speed whee//in distributor also supports sequential all by itself.

Not recommended for setups that drive the cam>distributor via a sloppy timing chain as well as the oil pump.(SBC as example)
the chain and other mechanical slop, plus oil pump camming will induce some timing jitter, although a high tooth count wheel apparently helps average it out.
On many engines there is no issue.