anybody out there has any ideas on why the idling of my car is erratic. When the car is in P or N, the idle shoots up to about 1500 rpm and when in gear around 1000 rpm. I think that this is unusually high.

A couple of observations:
- there seems to a strong smell of gas inside the car
- my full tank mileage is around 250 miles ...........

I would appreciate any comments from any body that might have experienced this or an expert with this topic.

we have the same engine (M102) and your problem might be the idle control valve. if you would like to take a look at it it's under the air cleaner and positioned between two intake manifolds. it's a common problem in the 124 body type, i think, most especially the earlier models.

do a search in this forum for idle control valve and it will give you the answers. I got mine in this forum. Yours might be cured by simply cleaning it with carb cleaners or better yet change the darn thing all together. Probably cost you about US$140.00 brand new. I bought a second hand and it cost me half of that and my idle stabilized after that. No problem so far.

oops, sorry, it's common with the 124 and 201 body type (forgot that).

Had a similar problem on my 2.6. There are two limit switches that must be closed to signal the ECU to command idle speed. One is the microswitch in the linkage and the other is the throttle position switch at the end of the throttle valve shaft. Test them both for continuity - they should be closed when the throttle is closed.

Disconnecting the harness connector from the throttle valve switch and checking for continuity showed that it was not closing. It's held to the throttle body housing with a couple of phillips head screws, which would not be easy to remove in those confines, so I douched it thoroughly with contact cleaner and kept cycling it by opening and closing the throttle. It eventually started registering continuity with the throttle closed, and the idle control speed returned to normal.

That was about a year ago and the idle speed control function is still working properly.

Duke

Do a search for posts by me. I have had this problem for a LONG time. Turned out to be a combination of things that were only remedied a couple days ago. Can you supply us with some more info? Did it just suddenly start idling high or has it been creaping up over time? How long has it been doing this? Have you or anyone else worked under the hood recently? I wish you the very best of luck.

I bought the car about 8 months ago and it has been idling high ever since. I will try to look into the suggestions over the weekend and hopefully come up with the solution. I will keep everyone posted.

I had a similiar problem a couple of years ago with my 85 190E and a benz mechanic told me to check my OVP relay. It can cause erratic idle..I replaced it and my idle smoothed out.

I don't have a service manual so what exactly is OVP and where is it located?

In the 85 it is behind the battery..Two black relays one is the fuel pump the other is the air con and to the right of them is a small silver relay with a red top and a fuse.

thanks for all the response guys!

I managed to get the idling to drop around 750 rpm when in Drive and around 1000 rpm when in N or P.

Just last week I ran into another problem however ......... my car started hesitating badly until I got to a Stop sign and the car just died. I manage to restart it but kept dying.

I'm wondering if the accelerator cable needs to be re-adjusted to bring the idling up a bit higher. I don't know if it's the OVP that might me causing the problem too. Is there any way that the OVP can be opened up and checked for flaws?

Two weeks ago, my 87 MB 190E 2.3 8V has stall problem when braking due to low rpm. Then, I replaced idle control valve, fuel pressure regulator and OVP. Now, the rpm become high to 1200 rpm in "P" or "N". In "R" or "D" is around 750rpm. No stall problem again, but I still need find out why cause the idle too high in "P" or "N".

Also, I only can get 380km in 48Liters gas. Is it poor gas consumption??

I basically replaced my distibutor caps, plugs and wires and that seemed to get the idling down a bit but the big fix was when I took it to an MB certified shop and they reconnected what was a disconnected EHA ....... this also helped me pass my emissions test.

good luck!

I would address this issue first. Sounds like a leaky fuel distributor or malfunctioning pressure regulator is causing a hyper-rich fuel misture, and the ECU is trying to compensate by kicking up air delivery at the idle control valve.

Steve

__________________
'91 MB 190E 2.3
'08 RAV4 Ltd 3.5
'83 Lazy Daze m'home 5.7

jeff-abalone

You are more or less in the lower end of the ballpark (abt 8km/litre), but it depends on your driving style and combination of city/highway driving.

I get anywhere between 400km to 490km from 44 litres of gas (that's like approx. between 9 to 11km/litre) but I drive the car a lot - be it in the city or highway.

My kid brother consistently gets about the same fuel mileage as you do and he basically drives to the office and back on weekdays - lots of short trips.

We both drive the 190E 1.8 Euro, which are RHDs.

Cheers.

jeff-abalone

Your poor fuel mileage could be a result of your higher idling.

My $0.02...

Cheers.