Fuel distributor has slight problem

[Kwame69]

I own a 1989 300e w/ 114,500 miles. I would like to know why sometimes when I drive, the car surges forward by itself. My mechanic suggest that I replace w/ a new Bosch fuel distributor. I did replace this unit w/ a aftermarket Python unit and had him make the change but its still doing the same thing prior to his installation. Need to know if there is something that I'm missing, Your input would be helpful. Thanks in Advance!!

[Robert Goodwin]

Yours is a problem that is difficult to diagnose without seeing the car. I have heard of the fuel pressure regulator and the oxygen sensor causing similar problems. Perhaps our readers have some additional ideas or experiences they can share.

[joeym7]

Hi I hope he checked the upper and lower chamber presures before changing the fuel distributer very exspensive you may be having a problem with the fule metering sensor on the side of the air housing it has a three wire connection at idle try tapping the housing and see if the idle changes.if you would like a copy of the trouble shooting tree give me your fax# and i will send it to you you can call me at 631-928-8818.joeym

[woodstock98]

I own a 1989 300e w/ 114,500 miles. I would like to know why sometimes when I drive, the car surges forward by itself. My mechanic suggest that I replace w/ a new Bosch fuel distributor. I did replace this unit w/ a aftermarket Python unit and had him make the change but its still doing the same thing prior to his installation. Need to know if there is something that I'm missing, Your input would be helpful. Thanks in Advance!!

I've had the same problem but I own a 1990 300CE and for the last few years have been working on it. In my case, the air/fuel mixture was off. The car was running too rich. Have someone check your fuel mixture as a start. Then check for vacuume leaks or have someone check for vacuume leaks.