2.2 hdi only runs with vac pipe off ? anti-pollution fault.

reef2k · Post by **reef2k** » 21 Apr 2009, 19:25

i cant even drive it unless i disconnect the vacuum pipe from that disc shaped device between the back of the head and baulkhead.its still very underpowered,smokes like mad and only does 15 MPG, but it should get me to the garage,which will save me 50 quid. any ideas what could be the problem could be, and could i do any damage if i drive it ?
thanks, Nick
2002 C5 2.2hdi

AndersDK · Post by **AndersDK** » 22 Apr 2009, 00:28

Hi -

The disc shaped device behind the engine is a vacuum pot operating a common butterfly valve axis for the engine cylinders air intake.
What exactly this arrangement is intended to do is beyond my knowledge.

From the schematic on citroen service net, I assume that the butterfly valves are part of either the idle control system or an emergency (strangling) system.
When you remove the vacuum pipe it seems that the vacuum pod releases the valve cam such the butterfly valves closes (strangles) the air intake.
This would limit air admission very much to the engine, and explains why your engine is weak and smoking.

I dont think it could harm the engine limping a short distance to your garage in this condition.

wheeler · Post by **wheeler** » 22 Apr 2009, 17:56

AndersDK wrote: The disc shaped device behind the engine is a vacuum pot operating a common butterfly valve axis for the engine cylinders air intake.
What exactly this arrangement is intended to do is beyond my knowledge.

This engine has a dual track inlet manifold & the butterflys are just to create different swirl depending on engine load. Either one one track or the other is open so it cant strangle the engine.

Reef2k do you have a picture of the unit you are disconnecting as i wouldnt imagine the swirl butterflys causing any problems like that & i cant think what your disconecting. Any work done on the car recently ?

cachaciero · Post by **cachaciero** » 22 Apr 2009, 19:52

AndersDK wrote:Hi -

The disc shaped device behind the engine is a vacuum pot operating a common butterfly valve axis for the engine cylinders air intake.
What exactly this arrangement is intended to do is beyond my knowledge.

Whoa! lets be careful here the Disk shaped device he is referring to is the brake servo diaphragm, the resevoir for the swirl valves and the turbo is underneath that.

The engine will run quite happily with the swirl butterfly disconnected although there is a marked improvement in low speed torque when the system is working correctly.

If the pipe that he has removed is the main vac feed to the servo then the car may move just don't know how well it will stop

Cacaciero

AndersDK · Post by **AndersDK** » 22 Apr 2009, 20:44

wheeler wrote:
AndersDK wrote: The disc shaped device behind the engine is a vacuum pot operating a common butterfly valve axis for the engine cylinders air intake.
What exactly this arrangement is intended to do is beyond my knowledge.
This engine has a dual track inlet manifold & the butterflys are just to create different swirl depending on engine load. Either one one track or the other is open so it cant strangle the engine.

Reef2k do you have a picture of the unit you are disconnecting as i wouldnt imagine the swirl butterflys causing any problems like that & i cant think what your disconecting. Any work done on the car recently ?

Tx wheeler. I had no idea what this arrangement does.

But its definately not the brake servo ...