Exhaust sound coming from smog pump, normal?
'97 Z-3 2.8 just installed the new secondary air pump as the old one froze up. The new pump works but I'm getting an exhaust sound from the pump after the pump shuts off. I pulled the hose off and the noise was coming from there and it felt like there was vacuum on it. So what else needs replacing now?
Re: Exhaust sound coming from smog pump, normal?
The pump that is sitting by the firewall is an air injection pump which pumps fresh air into the exhaust manifold at times when the engine is still cold, leaning out the exhaust gases by helping the cat run a "second burn" of the exhaust. If it is this pump then you should check the Vacuum Control Valve [P/N 11 72 1 744 255]located just off of the exhaust manifold. It's where the hose from the air pump runs to.
Hope this helps.