Secondary Air System more than likely would cause any misfires. You no codes for misfires I take it? Do you have access to a scanner that would have a misfire counter for each cylinder?

 

Reading my own reply is giving me a headache. Looks Like I just started typing. Lol

 

which valve - the aluminum one mounted to the head or the black box on the manifold?

(1) can get gunked up and stick
(5) can go bad, or the lines/valve before it could have a leak , not experienced in that

IIRC any vacuum leak could potentially cause a misfire code

 

Will need to check which cylinders are misfiring later tn

Changed (1) and the connecting hose. Will check (5) and its connecting lines

 

Code P1421 BMW: Secondary Air System Bank 1

Repair Information for P1421 BMW code. Learn what Secondary Air System Bank 1 means, location and how to repair?

www.autocodes.com

Code P1423 BMW: Secondary Air Injection System Bank 1 Insufficient Flow Detected (With Video)

Repair Information for P1423 BMW code. Learn what Secondary Air Injection System Bank 1 Insufficient Flow Detected means, location and how to repair?

www.autocodes.com

 

What year and model of E46 do you have? Knowing this will enable us to give you the correct model specific advice. Maybe add it to your profile.

Have you looked at your 4 fuel trims? If any are > 8% then you have vacuum leaks to find. Smoke test the engine as it is running lean.

DIY: Fuel trims, lean codes, misfires and how to...

Introduction It took me a long time to understand fuel trims, despite excellent videos by 50skid and excellent posts by JFOJ. I think I have a handle on them now, so I thought I would try to explain them as I understand them, and either help someone and/or get corrected. Here is my shot. Theory...

www.e46fanatics.com

How to Smoke Test

There are so many requests for solving problems that usually start with "do a smoke test for vacuum leaks" that there's a real need to have a single thread dedicated to smoke testing. Then we can just post the link to this thread when someone needs smoke testing info. Please chime in with your...

www.e46fanatics.com

 

It is a 2000 323i and have not looked at the fuel trims or done the smoke test. Appreciate you posting the links to those threads.