A/C , Idle and purge

[MANDALAY]

Cool many thanks !

So is there any way to use the CF line so as to provide the 12v pull up ? Are the switched inputs also 5 volts i thought it was only the digital ones

[MANDALAY]

Mark, this is what my mate tried for me.

BTW the CF input at the ECU is from the AC amplifier

If you were to attach a volt meter to "CF" at the ECU you would note low voltage when the fans are off (about 0.14V) and you would see battery voltage when the fans are running. Now I have always been weary about if the Engine ECU actually controls the fans on by providing a positive output on the CF line. I have never had a chance to verify and always assumed that it did not.
Today I went ahead and tested it with though I knew it could possibly damage the A/C amplifier. I went ahead and applied positive voltage to the CF line hoping that the A/C amplifier would accept a "high" signal. Wellll..... it did turn the fans on..... But it burnt out the A/C amplifier and my fans will not turn off as the A/C amplifier will no longer ground out the cooling fan relays.

So, on the SW20 the CF signal can only be used as a load signal. I do not know if the OEM ECU actually does anything when it realizes the Fans are on or not.
If it does I assume it may only adjust the idle speed slightly and perhaps add a degree or two of timing with a decay value to adjust for the initial increased electrical load.
Only speculations can be made.

[MarkMc]

Ahh dude,
A pull-up is usually through a 1000ohm resistor so the current is low.....just something to remember before you decide to blow anything else up.

All our pull-ups are to 5v, dig and AT/Switch. The A/C amplifier should just provide a ground path for whatever voltage is coming in on the CF wire so it should not really matter what voltage the pull-up is. Basically it is the ECU looking at it's own pull-up and when you short this to ground (remember 1000 ohm resistor) the ECU notices that there is no longer any voltage and this is the ECUs signal to do stuff. Usually there are two trigger voltage levels so that there is a bit of a no-mans-land in the middle so that the signal is only valid if it switches all the way, if these are lower than 5v our ECU should work as the factory one did. If you had not blown the thing up it may have been easy to work out what those voltage levels are......maybe try it on the replacement amplifier...?

[MANDALAY]

Thanks was my mates unit that blew his up as he has a spare and was willing to try as he wanted to know also. He did it before i could give him the drawing.

Problem is that the CF line was wired up to an output of the M800 A33 so mine could of also gone to heaven.

Anyway a new one is ordered.

The actual CF line is from the OEM ECU to the coil of FAN relay No1 as depicted below



So obviously when the fans are on the coil is energized and there would be battery voltage on the CF pin
and vice versa when the fans are off

This is from the manual where obviously E1 is earth



So i guess the 2 figures are 0-3 and 9-14 and no-mans-land as you put it b/w 3 - 9 volts


So how can i configure it on the Motec ? How should it be wired. Remember i have the M800 and have extra pins that are not used.

Thank you for you patience, what makes it harder is that this is a Beams JDM only engine that was in the MR2 with only 1000 made.

[MarkMc]

Well what do you want to use it for? The fans and A/C clutch and idle compensation are controlled by whatever switches the A/C request into the M800, nothing else. That CF pin looks like it is just an digital style input to the factory ECU so when ever the two switches in your modified drawing are connected to ground the input will have a low voltage.

[MANDALAY]

Thanks Mark,

Yes it really does look that way. I think ill just leave it disconnected and not worry about it. As you said its all taken care of by the AC input.

Maybe it was something for the future ? Who knows. Maybe its monitoring the fans ? to put the ECU in limp mode if something goes wrong with the engine. Either way looks like not required with the M800

I know we can fix up the idle with the AC on. Ive ordered another AC Amp just in case mine is blown. Only thing now is the fans dont come on when the AC is turned on which they should do but i guess maybe the dont because either because the AC and ACT lines arent hooked up or the AC Amp is blown .We will see.

I going to see if i can get someone with an OEM set up to disconnect that CF pin from the OEM ECU and see if it does anything ,

Again great to see the support from you Mark and MoTec !!!!!!!!!