Rough Idle

mercury
villager

#1

My 2001 Mercury Villager idles rough, but runs fine when driving. I replaced the plugs, wires, distributor cap, rotor and air filter. Then I took it to the shop and they said it had a code that indicated the #6 cylinder had misfired at some point and it required an intake manifold kit (O rings on the the injectors), but that failed to correct the problem too.


#2

Idle speed is controlled by the Idle Air Control (IAC) valve. If the valve is dirty or sticking it can cause a rough idle.


#3

Can the valve be cleaned or does it need to be replaced. How can I tell if it is sticking?


#4

If sticky it can usually be cleaned - just blow it out with some carb or intake cleaner.

I would also check for routine vacuum leaks - rather than something extreme like the manifold gasket.

Did this shop have anything to say after they ran up a huge bill w/out fixing it? Did they happen to check the compression?


#5

No, they didn’t give much information on what tests were performed. I am trying to get my facts together on the subject before I confront them about their poor service.

Thank you for the help!