PeachParts Mercedes-Benz Forum - View Single Post

stevebfl · #7 01-15-2005, 10:25 AM

Actually the ovp powers a number of systems. The two that are involved with running are mixture control and idle air control.

One thing to always remember, engine speed is determined by the amount of air not the amount of fuel. The various idle systems MB uses vary in their response to NO control. The V8s go to a very large airflow. The 4 and 6 cylinders go to a fixed middle psoition slightly larger than controlled no load condition. They do that as the system is a newer generation than the v8 system and the system was designed to "limp home" better with every version.

The way your car responds to no ovp is totally normal in the idle speed part. The fact that you are getting more power from it in the ovp missing condition is quite unusual. My first suggestion would be to try it a little differently. instead of pulling the ovp pull the EHA connection. Rememebr that ovp is powering two systems: idle control and mixture. The end result of all input is the signal to the idle valve in the idle contro case and the EHA in the mixture case. Your system if adjusted properly will not drive noticably different when warm with the EHA disconnected.

By disconnecting the EHA and idle valve separately you will accomplished a segmented reproduction of the act of pulling the ovp. It is hard to imagine power under acceleration being affected by disconnecting the idle valve, so do the test separately and verify.

If you find the EHA connection to have effect on the power, then you will need to learn how to monitor it. If you wish to learn how to view "cONTROL" on your motor and how to adjust it, monitoring EHA is imperative.