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Idle Problem That Fixed Itself.........almost.

4660 Views 141 Replies 6 Participants Last post by  LauraS
Today on my way into town I stopped at a stoplight which was red and the engine ideal wandered up rom about 500 to 750 RPM and seemed to have an ignition miss or something. I was a bit worried that it would stall but it didn't and once I accelerated the engine ran fine. This happened about 5 times when I had to wait for red lights. The temperature gauge read 90C and the ambient was about 22C. When I got to my destination I left the car for about 1 hour and when I returned the car sputtered but did start and settled into a nice 600RPM idle and from then on all of the way home it ran just fine? I have no idea what happened. Does anyone have any suggestions ? I would like to know of maybe the ICV might have been sticking or something else to look at.
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I would start by cleaning of of the grounds and replacing all the fuses with the ceramic copper ones. Also clean all the relay pins. I like a product called Deoxit. I know its a pain to do but it can save you aggravation down the road. There is a voltage gizmo that you can put in the Cigarette lighter plug that you can monitor running voltage, they are around $10.00 US.

Sounds like a weak battery to me. Starter clicking- charging battery then the car runs good. How old is the battery? The voltage can read good but it will eventualy fail because it does not hold the capacity. Could be the alternator, (or voltage regulator) or a possibility the ground side of the charging circuit could be at fault. The alternator needs a clean path to ground to work effectively. Put your Meter to Ohms , one lead to to the alternator case and the other to the battery ground. Want does it read? Go have your battery load tested. If its older that 5-7 years I would replace it.

The ground side of the circuit is as important as the power side for all of your electrical components to work properly. That is why I recommend making sure all the ground and fuses are clean before the start testing and replacing components. Remember the ECU is working with millivolts controlling components.
Here is Mercedes Electrical Troubleshooting Manual.


The residual pressure is 3.0 bar after one hour for a 2.6 190e- its in the manual.

When I bought my 1993 190e 2.6 5 speed with 255k miles and no service records I had Pierre inspect it. I was concerned about the suspension, brakes and other safety items since Florida does not have safety inspections. The distributor cap was missing the center carbon pin and a lot of carbon tracts and burnt contacts - so we did a tune up. Ran and started better. Also, two new fuel pumps. Gas just poured out of the line going to the fuel distributor! The spec is 1 liter in 40 seconds measured at the discharge line from the fuel regulator.

Pierre did check the fuel pressures, system pressures 5.3 bar and the lower chamber .4 bar lower. Pierre then recommended to set the lower chamber to -.45 bar difference and the car ran considerably better.

Anyways, check the ignition system , linkages not binding and throttle valve not sticking.

Other that doing a fuel volume test, your fuel system seems to be sound.

BTW- There is a fuel filter on the fuel line that enters the Fuel distributor- clean it.
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