RPM signal

[newsh]

I need to find the RPM signal which Turbosmart suggest I can get from the ECU.
But ""The E-Boost Street is ONLY able to accept an RPM signal in the form of a square wave that is switching between 0V and 3.5-12 volts."
Does anyone know if this signal is available on the S2? The car is a 3B but converted to ABY ECU.

[UrS4boy]

ECU pin-out and G28 signals

The engine speed sensor is on pin T55/49:

AAN (99% same as ABY) ECU pin-out:

http://forums.quattroworld.com/s4s6/msgs/21009.phtml

Somebody recently posted (here I think) a three channel oscilliscope out put with the G4, G40 and G28. I don't think the G28 was a square wave. (I can't find the screen shot of that post). (Sorry )

49/55-Input from G28 Engine Speed sensor - GY/GY -allows the ECU to figure out the engine RPMs and make the required decisions

[andyg plym]

John unsure of voltage but behind the dash clicks it's the green and blue wire that feeds the Rev counter, I use it to take a feed for my shift lights

[Error404]

The VR sensor isn't a square wave, but I would guess the ECU output to the rev counter probably is - purple wire at pin 7 of the black T10 connector on aux relay panel under drivers side dash
If not you can get a VR conditioner, a little board that converts the waveform to a digital pulse

[newsh]

Ok cool, thanks chaps! With the help of your postings I make it this.

So, it's a purple wire from pin 40 at the ECU (in 3B ECU it used to be in pin 6 before the pin swap )

Changes to blue and green at T10 in the aux relay carrier before going to the back of the dash. T26/22 to G5 which is the tacho.

I shall go and find it.

[andy10v]

I wired my shift light up to the blue/green wire on the back of the rev counter plug if that helps.

[newsh]

Got this wired up to blue/green on the back of the gauge cluster but disappointingly the signal gives a reading of only a few rpm at idle and zero as revs rise.

[UrS4boy]

The RPM signal comes into the T10 connector on the auxilliary relay panel as a lilac (purple) wire in Pin 7 (T10/7). It leaves the T10 as a green/blue wire on its way to the G5 tachometer, entering the instrument cluster on Pin T26/22.

http://www.s2central.net/S2_Schematics/B/B73-07.pdf

[newsh]

Yes, I connected it but I don't think the waveform is correct to drive the eBoost unit.

I've just buzzed the wire through from the T10 connector (which is obscured behind the loom in my 3B) to the wire I attached to the back of the cluster, it's the same wire.

The RPM display will not appear unless the wire is connected. When connected it appears but reads 006, should be 008 at 800 (RPM x 100), rev it anf it changes to 005 or 000 .

[Jonas_R]

Did you remember to set engine as 5 cylinder on the eboost?

I had the eboost 2 and used setpoint mapping with RPM, so it does work.

[newsh]

Did you remember to set engine as 5 cylinder on the eboost?

I had the eboost 2 and used setpoint mapping with RPM, so it does work.

Good to know, I wonder why mine doesnt seem to work

Definitely set to 5 cyl.

Did you use the tacho feed from ECU to the back of the tacho?
Did you use a resistor?

[Jonas_R]

Hi,

Yeah I just used the tacho signal from the instrument cluster.

Can't remember about the resistor to be honest.

But I guess you could just try it out and see if that helps?