There is a small vacuum hose going to the secondary air injection valve, check it for breakage.

Answered by Dr. Hagerty (expert)
9,669 answers provided

brought it in to bmw. was told that they need to replace the secondary air pump for $985!!!
I honestly do not know how a part can be broken while the car drove beautifully. how does this affect the vehicle? wouldn't the warning lights turn on for this? i have not yet ok'd for them to order the part. cost above is just for the part! i need to find another option. unfortunately, i am unsure if that is the problem.

Response from gtimmins
1 question asked

The secondary air pump supplies pressurized air to the exhaust manifold, when the engine is first started from cold, this quickens the catalytic converters start time. The pumps have been known to fail and it will not effect driveability. I suspect it is not the pump, but the vacuum hose that controls the valve that sits at the exhaust manifold. 2001 Z3 did not have a 4 cylinder so I have included a link to the site I use to describe parts as well as giving you an exploded view. http://www.realoem.com/bmw/showparts.do?model=CN33&mospid=48093&btnr=11_2203&hg=11&fg=45

So going back to my earlier post about the vacuum hose, it can be viewed in the link and did it get inspected? If it is corrupted, the secondary air will not flow, check that next and let me know what you have found.

Answered by Dr. Hagerty (expert)
9,669 answers provided