PeachParts Mercedes-Benz Forum - View Single Post

Chadahar · #9 11-02-2008, 05:53 PM

I would try several things BEFORE I had to go into the throttle body location to repair the switch.

Try taking off the ICV the round valve in front of the air cleaner(it has two large black rubber hoses plugged into: 1, the rear, 2. the side.) and clean it with carb cleaner.
First, Disconnect the switch from the forward end and see if that makes a difference in the idle speed. (Or is this what you thought was the TPS?)
Spray it in the side port holding the valve with the end port pointing down. Hold your thmb over the rear port and slosh the carb cleaner around and spray until it runs clean. They do gum up over time.

It sounds more like Idle Control than Throttle Positioning Switch. Did you rap on the ICU between the firewalls? Result?
You have to give it a healthy rap.

The following is NOT Road Warrior friendly, especially if you have to use your car as a daily driver.

To get to the TPS you have to remove all the fuel lines from the fuel dist., leave the FD on the Air Metering Plenum, then remove the Air Metering Plenum then use metric Allen socket(7mm if I remember correctly) to remove the throttle body. While you are in there replace all the vacuum lines so you don't have to go back int there soon. I'd replace the 3/2 valve on the TB too along with the TPS.
I just performed this chore on my Euro 500 SEC and it's no fun, but doable DIY. My car had the manifold gaskets and donuts replaced 41,000 miles ago and I decided NOT to replace them at this time. However, if these parts had not been replaced I would have replaced those as well.

Pretty tough decision to go in there when I think your problem is either in the ICU, ICV the OVP (check it too). I would replace these or at least test them to see if they are OK way before I'd elect to "GO IN THERE"....especially if you don't have too.