When is the supercharger suposed to be on?

[BIGBOBO]

Just figuring out the last few problems on my NA to SC swap and this is one of them.

When is the SC clutch suposed to be engaged? My supercharger seems to turn slowly at idle (which is normal due to the air passing through I think) but as soon as I rev it (even a little bit) it will engage and stay engaged untill I release the throttle. Even at low revs (below 2000) it's engaged.

Is this normal behaviour? I thought the SC only was suposed to be on at higher revs or full throttle?

If not, what could cause this problem?

[Ben]

Sounds normal to me...

The SC engages dependent on throttle position, not engine revs. So if you put your foot down at 1000rpm it will engage and give instant boost. On a steady throttle or a trailing throttle it should be disengaged.

The whole point of a supercharger is that it doesn't give you the same lag as a turbo, hence why it can be active right through the rev range

[BIGBOBO]

I'll perform some more thorough tests tonight but last night I kept it stead around 2000 rpm for about 20 seconds and it was still engaged.

Would it matter if the car is being driven or not? It's still parked in the garage until I figure everything out.

[MartG]

IIRC the ECU activates the SC clutch based on a combination of throttle position, manifold vacuum, and rpm.

[JMR_AW11]

Dunno if this helps but I reverse engineered the ECU program code for the JDM (AFM) SC control a few years ago.

Sadly I've forgotten a lot of it but I did post up some info on Mark and Lauren's SC forum a few years ago with a flow chart showing how the supercharger control code flows in the ECU. Maybe it is still there?

I do remember getting Mark to test some of it out. eg testing the release timer for the supercharger. I can remember it having various release times. eg something like six seconds or 12 seconds depending on how the car was driven. I think the timers can be constantly reset so you could keep it engaged for longer than 12 seconds if you drove it a certain way.

All this stuff could be logged from the ECU with a PC and you could even watch the timers count down and know when it was about to release the SC.

Here's an old photobucket image of some typical data taken from the ECU's internal datalog interface.




You won't be able to work it all out from simply driving it but the program code for the SC relay control is only a few dozen bytes long so it's fairly easy to predict the behaviour from reading the program code.

Please can I ask that nobody ask me for any of the hardware or software to do this ECU logging because I stopped looking at this stuff several years ago and I doubt I could find the info anymore.

Note that I think I sold a few SC ECUs with the software and the logger hardware aseveral years ago. Not sure if Mark still has one. I probably have a 'logger' ECU somewhere but I doubt I could find the software after 6 years!

[ulysess1966]

Or you can go Mad Max like me and have a 3 position switch -

SC OFF (Economy mode)
SC ECU (Normal)
SC Mental (Permanently Enganged)

Very easy to do with a switch and a relay.