Purge Cannister Solenoid Valve

[Daviewonder 533 3 Cars]

Hello all,

 

Just finishing tidying up the wiring on my 2.0 turbo conversion and ive found a couple of stray wires that go to the "purge cannister solenoid valve" one comes from ecu pin 5 and the other comes from lamda pin 1. Can I leave these disconnected or do I need to connect these to a purge valve?

 

cheers

[pug_ham 244 3 Cars]

AFAIK you should be fine to leave them disconnected.

 

Graham.

[Daviewonder 533 3 Cars]

AFAIK you should be fine to leave them disconnected.

 

Graham.

 

Ok mate, I just wanted to be sure.

 

thanks, Dave.

[DrSarty 90 1 Cars]

Yeah. It's emissions nonsense.

[petert 592]

If you remove the solenoid you will need to put a 1.2Kohm resistor in its place. Otherwise the ECU will fault.

[DrSarty 90 1 Cars]

If you remove the solenoid you will need to put a 1.2Kohm resistor in its place. Otherwise the ECU will fault.

 

Aha!!! The master speaketh.

 

If the resistor goes to the purge valve pin on the ECU, what does the other end of the resistor go to please? Of course I know resistors aren't polarised so it matters not which way round it is; but does one end go to an ECU ground, e.g. the casing?

[Tom Fenton 1,542]

The resistor would go between the two pins that the purge valve connects to, to fool the ECU into thinking there is the valve there. Alternatively you could just plug the valve in and tuck it somewhere out of the way, not piped to anything.

[DrSarty 90 1 Cars]

The resistor would go between the two pins that the purge valve connects to, to fool the ECU into thinking there is the valve there. Alternatively you could just plug the valve in and tuck it somewhere out of the way, not piped to anything.

 

I don't think that's right Tom.

 

I've just checked the Motronic MP1.3 diagram and it shows that Pin#5 on the ECU which controls the purge valve (solenoid) is just a ground switch, and there is only one ECU pin going to the CPV because the other side is a switched 12v.

 

This means the 1200 Ohm (1.2kOhm) resistor goes between ECU pin#5 and a 12v switched live source when there's no CPV.

 

In fact it's pictured in the diagram with dotted lines.

Edited September 28, 2009 by DrSarty

[Tom Fenton 1,542]

Explain it however you like, but in practise if you have a loom with a plug for the purge valve, you just place a resistor between the two pins of the plug, as I said above.

[Roman 0]

I don't think that's right Tom.

 

I've just checked the Motronic MP1.3 diagram and it shows that Pin#5 on the ECU which controls the purge valve (solenoid) is just a ground switch, and there is only one ECU pin going to the CPV because the other side is a switched 12v.

 

This means the 1200 Ohm (1.2kOhm) resistor goes between ECU pin#5 and a 12v switched live source when there's no CPV.

 

In fact it's pictured in the diagram with dotted lines.

tom is right..... solenoid is a coil and coil is infact some sort of resistor

[DrSarty 90 1 Cars]

Hold your horses fellas; we're talking the same thing.

 

Tom's saying across the pins of the plug to the CPV which is correct.

 

I'm saying which pin(s) on the ECU, and as such there is only one pin which goes to the CPV. The other is a 12v feed from somewhere else.

 

One situation is relevant if someone uses the OE loom and the other if someone makes their own, and I believe Dave has made his own.

 

It's not a case of right or wrong, but it does seem the ECU cannot 'see' an open circuit and hence something needs to be put in there.

 

There is a good reason/benefit here for both explanations.

[Tom Fenton 1,542]

I don't think that's right Tom.

 

 

 

Tom's saying across the pins of the plug to the CPV which is correct.

 

 

 

Make your bloody mind up?

[DrSarty 90 1 Cars]

Make your bloody mind up?

 

Because we were talking about the other pin 'on the ECU' that goes to the CPV, when only one does. It's a switched ground.

 

Using the connector that went to the CPV was a stroke of genius, but if Davie or anyone else doesn't have it because they've made a new loom, then they need to know that one end of the resistor goes to pin 5 on the ECU and the other goes to a 12v sw feed.

 

As I said: two worthwhile explanations/work rounds depending on what loom you use.

 

Agreed?

 

And for the record Tom, you were right, and I was wrong; but we were talking cross-purposes, plugs versus ECU pins.

Edited September 28, 2009 by DrSarty

[Daviewonder 533 3 Cars]

Ok thanks guys. So I need to get a 1.2Kohm resistor and put it between the wires where the solenoid was on the original loom. Will it be ok if I wrap the resistor up with the rest of the loom or does it get too hot?

[leon 1.9 0]

Current is ~10mA (12V/ 1200 Ohms) so it shouldn't get too hot. I'd suggest leaving the resistor exposed to some air though if possible. Other option is just to link the plug out, then cut one of the wires that feeds the plug in a more accessible place (either from the lambda or ecu) and solder/ wire in the resistor.

 

The power through the resistor is ~1/8th of a Watt (12V * 0.01A) so that would be the lowest power-rated resistor you could use. A higher power rating might make it cooler though (I think).