I have a 1992 E250 RV with a 5.8 engine. When I start the engine cold it races very high. I don't have a tach on it, but it sounds like 2000 RPM or so. If I crimp the vacuum line from the intake manifold to the EGR valve, it drops to a slow idle. After it warms up, it drops to a normal idle.
Since it works okay warm, it doesn't sound to me like the valve is bad. It sounds like a control problem. I know there is a vacuum solenoid and a position sensor.
Any help diagnosing the problem would be greatly appreciated.

 

The EGR valve is controlled by the ECA which sends electrical commands to a pulse width modulated vacuum regulator solenoid or pair of solenoids depending on the engine calibration. The pair of solenoids are called the Exhaust Gas Recirculation Control (EGRC) and the Exhaust Gas Recirculation Vent (EGRV). The single solenoid is called the Exhaust Gas Recirculation valve Vacuum Regulator (EVR) The ECA makes the ground for the solenoid to operate. You can check to see if the valve is stuck in the open position. If it is being held there by the ECA then the ECA is suspect, but I don't think that is the case. There should be no vacuum to the EGR valve when cold or at idle.

 

Thanks, That's good to know. Also, I scanned the codes and received a code of 28. This was either KOEO or a stored CM code. I did it manually and was a little confused about which it was. The table I found listed this as a VAT problem. The only VAT I am aware of is on Turbo engines. Of course, I don't have one. Anyone have a better list of codes?

 

For a 5.8 engine there is no code 28.
You may need to try and get the codes again.
I believe your truck has an E4OD trans , does it not?

 

Problem solved. Crimpimg the vacuum line didn't affect the EGR, It plugged up a vacuum leak. I still don't know why it ran OK after warming up?
I now need to reset the codes and drive it a bit to see if new codes are set.
Yes, I have an E40D transmission.

Thanks for the Help!!

 

After the engine warms up the computer adjusts the mixture , idle speed etc., whereas when cold it doesn't control it quite as much.