[Sailor24]

Which code do you have? AA or AB.

 

[Rog]

Which code do you have? AA or AB.

???

P0411 I want to check the solenoid to see if it's working.

 

[Sailor24]

Sorry AA and AB are the proper BMW hex codes. P0411 is a OBD code I am bilingual so it is the same as AA.
First look here. RealOEM.com   BMW E39 M5 AIR PUMP F VACUUM CONTROL

My assumption is you are looking for part #1? One way to see if it is working is pull the vacuum hose of the valve I think you replaced when the air pump is running. First two minutes of a cold start. (found here) RealOEM.com   BMW E39 M5 EMISSION CONTROL-AIR PUMP
part #8

 

[ard]

and there is no carbon build up.

How was this definitive diagnosis made?

 

[Rog]

Well, short of pulling off the heads to change the air valve, which would be rather overkill I inspected the tube and inlets, there is nothing there at all. I would be very surprised if there was anything to write home about inside.
I decided to change the valve since it is a cheap part and the most common mode of failure, but alas no success, so i'll have to delve a bit deeper and see what else i can find. Incidentally, the valve I took off was jammed, but it's had this fault for a while so I guess it's just because it's been stuck in the same postition for ages. Also, it's a UK spec car, and if I am correct would be highly unlikely that it's carbon build up.

 

[ard]

Also, it's a UK spec car, and if I am correct would be highly unlikely that it's carbon build up.

I was under the impression that the on reason this is true is that US spec cars will set the MIL/CEL light for an AA code, but OUS the code may occur but is 'silent' (ie does not set the light.)

 

[Sailor24]

I was under the impression that the on reason this is true is that US spec cars will set the MIL/CEL light for an AA code, but OUS the code may occur but is 'silent' (ie does not set the light.)

I am a bit baffled too. I know that euro gas is better, but CBU is engine design, I was guessing. I find it hard to believe that a euro engine could not get CBU. I do have a way to test to see if the air going in the pump comes out the tailpipes. Complete the test then you know for sure.

 

[Rog]

I see your point guys, but I have yet to see anyone on the board (unless I have missed it) that has a Euro spec car with this issue.
Your statement about engine design and fuel is contradictory by the way, without fuel you don't get carbon, i think it is fair to consider that fuel may be the issue and not the engine itself, but I welcome any discussion on this.

 

[Sailor24]

I see your point guys, but I have yet to see anyone on the board (unless I have missed it) that has a Euro spec car with this issue.
Your statement about engine design and fuel is contradictory by the way, without fuel you don't get carbon, i think it is fair to consider that fuel may be the issue and not the engine itself, but I welcome any discussion on this.

The bad design is the SAI tube that connects the two exhaust manifolds. It allows flow of carbon in the exhaust gas to pass through it while equalizing the pressure. Don't think I understand what you mean "contradictory". Obviously the HC is where the carbon comes from. Could also be driving conditions or practices. More than likely it is the software in the north American car and this tube that connects the banks. Specifically how the DME responds to our tighter emission standards. NOx control is the issue that would move the exhaust back and forth through the SAI tube. It may not be as strong in the Euro cars.

 

[Rog]

Can somone tell me where the solenoid is please....that is all I want to know.

 

[Sailor24]

I already posted the map, but it is under the plenum on the right side. follow the vacuum line back to it.