E38 Resurrection - Emission control Air pump/assembly

[johndownunder]

Hi all, getting really close to firing up the beast, basically putting all hoses, leads etc back in place.
Anyway was connecting air pump hose back into valve assembly and notice previous owner had blocked up internals of valve where hose connects with silastic! Coincidentally had to clean out each head where metal pipework attaches to head due complete carbon blockage.

Have read through Bentley's description which explains the pump only operates on start for two minutes to reduce emissions and speed up heating of catalytic converts but is it ok for the pump to run with a blocked outlet, was it blocked because the pump had failed prior or was it done to isolate the emissions system to increase power? Anyway, why was this done and should it be undone?
Many thanks
John

[ryunk]

Hmm good question. I would be curious if the electrical connector to the secondary air pump is disconnected or the fuse is pulled. Seems if they plugged up the air line then they would have no need for the pump to operate. Could be either the pump went bad or they just wanted to remove the emission feature altogether and they essentially plugged the line, without removing the pipes. By plugging the line would ensure that the exhaust does not make its way up a pathway through a stuck valve through the piping. I don't know of a performance benefit by removing the emission system. Others (non-BMW) have plugged the exhaust manifold when they delete the Emission Control Air system, likely done only to clean up the area around the engine when system goes bad. Should it be undone? Depends, your call, If you want to avoid engine codes and to provide the benefits of the emission system at cold start then it must be undone, otherwise.......