I have a 2000 Mercury Grand Marquis. I recently just replaced the IAC.
In the mornig now in Pa its very cold. When I start my car it was idling really rough and at any given time it would start humming. Loud or low it was humming. It did this off and on until the car warmed up. Yesterday I placed the IAC thinking that since the car was so old it was locking up and causing the rough idle and humming. After the install, the rough idle was gone. After letting it run for 5 mins it started humming again. Today I removed the IAC checked the placement. I have a cone air filter and and heat shield installed on the stock intake hose. I removed that whole thing reinstalled tight and sealed as possible, and cleaned the throttle plate off. Now the car hummes whenever Im not stepping on the pedal. Any idea what it is?
In the mornig now in Pa its very cold. When I start my car it was idling really rough and at any given time it would start humming. Loud or low it was humming. It did this off and on until the car warmed up. Yesterday I placed the IAC thinking that since the car was so old it was locking up and causing the rough idle and humming. After the install, the rough idle was gone. After letting it run for 5 mins it started humming again. Today I removed the IAC checked the placement. I have a cone air filter and and heat shield installed on the stock intake hose. I removed that whole thing reinstalled tight and sealed as possible, and cleaned the throttle plate off. Now the car hummes whenever Im not stepping on the pedal. Any idea what it is?