Secondary Air Injection Valve

[dan f]

Hi.

Can anyone tell me what this is, what it does and why it may become blocked?

I have been informed by my dealer that this is the case on my 2001 SLK 200K and they are in the process of fixing it.

Will its blockage cause any other problems? I was told that depending on duration of the blockage, it could have caused other problems to occur.

Any comments gratefully received.

Cheers,
Dan.

 

[dan f]

Surely someone must have an idea what this is and what it does.

 

[Ramius]

Will its blockage cause any other problems? I was told that depending on duration of the blockage, it could have caused other problems to occur.

No idea what the part is, what is does (other than inject air) but didnt like the term above.

I have little faith in many dealers and that to me sounds like a meal ticket to additional work and a higher bill!

 

[davidsl500]

In a nutshell, all the fuel isnt burnt during combustion in the engine and these gases, with high levels of co and other nasties would pass out through the exhaust into the air causing high emmissions. Air is injected into the exhaust through the secondary system, close to the engine exhaust manifolds to allow more oxygen so that these gasses can be combusted further to reduce the emmissions.

You know where this is going don't you !! If air isnt injected then unburnt fuel and gasses flow through... the .....good old CAT and could lead to damage.....

 

[dan f]

Hi.

Thanks for the replies.

I see what you are saying. Mind you the things I have noticed since it was done are that the pick up from standstill/low speeds is *much* better even making the car feel a fair bit faster, also the engine is a LOT smoother and quieter at speed.

How would fixing the air injection into the exhaust do that?

Cheers,
Dan.

 

[996jimbo]

I guess burning unburnt fuel in the manifold helps with the flow of gas through and throught the engine.

2 stroke engines (work completely differently but) rely on pressure pulses from the exhaust to help draw fuel in and close the cylinder and draw out exhaust gasses. This is efficient at certain revs hence the narrow power bands. Though they work differently the point is that the exhaust side of the process can still have quite an effect on the performance.