What is this cylindrical unit for ??

sbraud · Unread post by **sbraud** » 09 Feb 2007, 16:42

Can anyone shed any light on what this is? I have a feeling it’s to do with air mixture but to what end? It on my 2.0 16v 155bhp XU10J4 unit (1994) Xantia.

It’s the cylindrical unit attached to side of air filter box with two hoses attached.

In relation to rest of engine…

The small pipe on right of cylindrical unit then attaches to this sensor/electrical unit of some kind. Then pipe makes its way to and is attached to the air intake throttle housing.

The thicker hose on right of cylindrical unit disappears into L/H F wing. (sorry it’s dark)

Any help world be gratefully appreciated.

Cheers
Steve

Unread post by **philhoward** » 09 Feb 2007, 17:35

99% sure it's the evaporative charcoal cannister (aka a purge cannister). It's effectively the vent from the petrol tank (so you don't let petrol fumes into the atmosphere...another emmissions gizmo). The pipe leading off from it to the inlet tract is how the engine "eats" the fumes from the tank; the solenoid is energised every now and then by the ECU.

André Citroën · Unread post by **André Citroën** » 09 Feb 2007, 19:22

philhoward wrote:99% sure it's the evaporative charcoal cannister (aka a purge cannister). It's effectively the vent from the petrol tank (so you don't let petrol fumes into the atmosphere...another emmissions gizmo). The pipe leading off from it to the inlet tract is how the engine "eats" the fumes from the tank; the solenoid is energised every now and then by the ECU.

100% right answer from philhoward

sbraud · Unread post by **sbraud** » 11 Feb 2007, 10:30

Thanks philhoward and Andre Citroen. Really appreciate your help!

Would I be right in thinking, if thin pipe (pic1) became unattached, as it did a couple of weeks ago, the ECU purge would allow air and not fumes into inlet tract and this may/would cause idle to drop to zero rpm (stall), as it did a couple of weeks ago. This only happen for a short time sitting in traffic. Took foot of pedal and engine would stall straight away.

After reconnecting pipe, problem has not reoccurred (yet !!)

Cheers
Steve

AndersDK · Unread post by **AndersDK** » 11 Feb 2007, 14:21

Yep you are right.

This purge valve & charcoal canister are fitted to all recent cars. When (not 'if'

) the small hose from the purge valve to the inlet splits - the idle revs is lost or goes insane - because of the good old wellknown problem : false air

sbraud · Unread post by **sbraud** » 11 Feb 2007, 14:32

Thanks Anders

mallyg · Unread post by **mallyg** » 11 Feb 2007, 19:51

i too have had the thin pipe break at the canister. is there a quick fix other than buying a new canister or do i have to bite the bullet and buy a new canister

AndersDK · Unread post by **AndersDK** » 11 Feb 2007, 22:05

mallyg wrote:i too have had the thin pipe break at the canister. is there a quick fix other than buying a new canister or do i have to bite the bullet and buy a new canister

Had about the same problem on a diesel vacuum pump.
One of the small plastic studs broke off, leaving the suction hose impossible to connect. No fun to spend approx £90 and 1mth's lead time to get a new pump.

Found out that the standard 3.5mm (the thinner ones) of hydraulic/brake lines would fit almost exactly inside the hole left from the broken stud. Some fidling with a drillbit and a piece of the piping was a snug fit. Used a tiny dap of liquid sealant (bathroom silicone is perfect) on the pipe before it went into place. Reconnected the hose.
It has worked a treat now for 3 years - and still works of course

If trouble finding such a metallic pipe - try any plastic extension pipe from spray cans. Even the "plastic tube" from a cotton stick may be the part you need

The pipe internal diameter is of no concern. It will just take a few seconds more until the canister is purged.

EDIT : forgot to mention that the broken off stud piece was drilled up accordingly to fit over the repair stud - with sealant. Otherwise you would be left with a stud diameter way too small for the hose.