rough ideling
5th Gear Member
Joined: Feb 2005
Posts: 2,167
From: Houston
RE: rough ideling
here bryan
The EGR valve is the main emissions control component in the exhaust gas recirculation system. The valve is located on the intake manifold, and opens a small passageway between the exhaust and intake manifold to allow a metered amount of exhaust to flow back into the engine. This reduces combustion temperatures and helps control the formation of oxides of nitrogen. The EGR valve is opened by the application of vacuum to its control diaphragm. Some also require a certain amount of exhaust back pressure before they'll open. On newer vehicles, the valve is electronic and uses one or more solenoids or a small stepper motor. The valve should remain closed while the engine is cold and at idle. It should only open once the engine has warmed up and is running at part-throttle. If the valve sticks shut (or is disconnected), NOX emissions will soar and detonation will often result (See Detonation and Spark Knock). If it sticks in the open position or fails to close all the way, it acts like a vacuum leak resulting in a rough idle, hesitation and possible stalling.
The EGR valve is the main emissions control component in the exhaust gas recirculation system. The valve is located on the intake manifold, and opens a small passageway between the exhaust and intake manifold to allow a metered amount of exhaust to flow back into the engine. This reduces combustion temperatures and helps control the formation of oxides of nitrogen. The EGR valve is opened by the application of vacuum to its control diaphragm. Some also require a certain amount of exhaust back pressure before they'll open. On newer vehicles, the valve is electronic and uses one or more solenoids or a small stepper motor. The valve should remain closed while the engine is cold and at idle. It should only open once the engine has warmed up and is running at part-throttle. If the valve sticks shut (or is disconnected), NOX emissions will soar and detonation will often result (See Detonation and Spark Knock). If it sticks in the open position or fails to close all the way, it acts like a vacuum leak resulting in a rough idle, hesitation and possible stalling.
2nd Gear Member
Joined: Oct 2006
Posts: 412
From:
RE: rough ideling
before you buy anotherEGR valve...i also found this from 3.8mustang
http://www.3.8mustang.com/forum/showthread.php?t=93943
http://www.3.8mustang.com/forum/showthread.php?t=93943
4th Gear Member
Joined: Jan 2007
Posts: 1,758
From: Eureka, Ca.
RE: rough ideling
I've seen egr valves and iac's stick and yet no check engine light on. If the motors that control them are working the computer thinks they are OK but they can still be stuck and cause rough idling. You might want to have them looked at before throwing money at it. I've seen people spend lots of money on parts hoping they would fix the problem and end up going to a shop anyway in the end.
