Any news, Problem Solved???:confused:

Not yet...soon...I broke my forearm snowboarding, so it is slowing me down... :(

Well!! There you go then. You should have had a Mercedes Benz snowboard equipped with anti skid control and airbags and you then would have not done your arm in.;)

As long as your vacuum gauge needle is sitting around the area just off the red at idle the engine will never idle properly. The gauge being a symptom of the problem.

The needle should be right over to the left at idle (in park).

I haven't read all the posts, but I believe there is a microswitch that is closed when the car is at idle. The switch (at least on the 190e) is located at the end of the throttle cable, I think it has something to do with deceleration. Have you checked that this switch functions as it should?

Bummer. But you can tell us the real story man, you were trying to impress some snow bunnie:D

Well its been 5 weeks and I am FINALLY out of a cast....

With some help this weekend I can get the tranny pulled on the 300TE to fix the leak. Once that is done I am right dead on track to look at the potentiometer. I just can't live with this leak any longer as its destroying the road outside :(

I have exactly the same problems that everyone is describing here. I have done just about everything as far as replacing / substituting suspect parts. However I have one exception - an intermittent ECU. When the ECU is working, the rough idle problem is there. In order to determining if the problem is in the ECU or any of the associated functions it tends to I have unplugged the ECU and I am running in open loop, no idle control --- etc. The problems at idle are still there. That tells me that the problem is purely mechanical in nature and not associated with the ECU. Yea I hear ya - the engine is not at lambda, no acceleration enrichment blah, blah, blah etc. Yes I agree. but what I am concentrating on is the problems at idle or in the low RPM range. The engine should perform reasonable well since it is in "limp home" mode. Yes the power is somewhat reduced but it's not bad. I have not been able to track down the problem but I am continuing to work on it.

I would love to get an update to what others have come up with. I will post my results as soon as I have a solution.

This is a great thread. I'm wondering the the potentiometer was ever replaced and problem solved or not...anyone know?

I end up getting caught up with other projects...or other problems...

First the transmission leak...now the head gasket leaking again :rolleyes:

One day...

Well....it sure does look good sittimg there in the picture:) I'm not sure if any of us ever really solve the idle issue on these cars....

My M103 has just 60K miles and I wish it would idle smoother. New injectors, cap, rotor, wires, correct plugs and 02 sensor. Almost there....

I actually replaced the Air Temp Sensor as someone suggested and it improved my idle and stalling today in these hot temps. Then I went and bought Bosch +2 Irridium Plugs ($32.00) and it got even better. It still doesn't want to start though. Must be my fuel accumulator losing the pressure build up to the fuel distributor.

Anything new on the idle?

My idle is not perfect but good enough, not much more I can do about it, 9 on a scale of 10 of smoothness. Car runs super so I've come to accept it.

Interesting that this thread has been resurrected.

I'll take my shot at solving the problem...since I've had a rough idle in my 500SL for over three years now. In that time the engine has been torn completely down and rebuilt. The problem still exists at low idle. Increase the RPM and it's smooth as silk. Tech manual says the idle on mine should be 650rpm +100 or -50. So, from 600-750rpm. Mine sits at 500rpm. Adjusting the mixture on the fuel distributor doesn't make the problem go away. Nor does increasing the idle by manually adjusting the linkage. The electronics bring the idle right back to 500rpm.

My mechanic has told me that the problem is in the throttle valve. Looking at my engine (117.962) manual, I'll guess a weak spring (part # 117 993 03 10). Or it could just be an adjustment to the butterfly plate. Getting to the throttle valve is a bear.

The throttle valve sits at the front of the engine and down low. The throat of the black boot (air flow housing) that bolts to the the bottom of the air flow sensor, clamps to the throttle valve housing. In order to get there, you have to remove the fuel distributor and air flow sensor. Notihing particularly hard about doing that, but it is time consuming.

What the adjustment will be is beyond me. I don't know if there is a screw type adjustment that you can make with an electronic meter or not. However, this is too big a job to tie into just on the hope you can figure it out once there.

Sometime in the next month or so I plan to tear into it and sic my mechanic on the fix.

Don