my idle fluctuates from 800rpm to 1000rpm, any suggestions on what could be the cause?.....& i was wondering if this car's accelarator cable assembly came with a return spring that attaches from the cable to a tiny whole on the left side of the air-filter casing where its bolted to the engine compartment.--left meaning me in the drivers seat. your responds are appreciated!

Sounds like you car is running to rich. You can turn it down using an allen key, think its 2.5mm. Their is a shaft right behind the air filter box. Put the allen key in their and do small turns to lean the car out. I adjusted mine to run rich and I went to far, mine did the same idle from 800-1000 until I turned it down some. As for the return spring, yes, their is. I had a shop replace the ball joints on my throttle and when they did they lost my return spring. It was on back order from Germany for literally 3 months. Needless to say I was upset, and I ordered a few extra springs so I wouldn't run into this problem again.

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Adrian Eckenrod
MBCA, PCA, BMWCCA & SCCA* member
86 190 2.3-16
83 944 ITS Racer

(a Adrian! which way should i turn the idle mixture to lean it out).>>>>my car has 2 return springs attached to the accelarater cable-- one attaches on top of the cable assembly and heads forward to the air-filter box, and the other attaches from the bottom of the cable assembly and heads downward towards the engine compartment.-THE ONE ON TOP LOOKS AS IF IT DOESN'T BELONG THERE...am i right or wrong???

Since the idle speed is computer controlled the fuel mixture shouldn't affect the idle speed. If the idle fluctuates then something is sending a bad signal to the computer. The most common failure on this engine is the air flow sensor. Have it tested by qualified M.B. tech!!

thank you MB DOC= I WILL GET THE AIR FLOW SENSOR CHECKED OUT!

The two springs you are refering too are correct. That top on (attached to the throttle cable) is just to give the cable some tension. Their is actually a third spring below the air filter box (this is the one my shop lost). It is the spring that gives your pedal tension (also a spring for pedal tension in the car at the pedal too). Your car might have a steel anti-tamper lock on the fuel/air mixture control. They are suppose to but I took mine off. If you have the anti-tamper lock, the shaft behind the air filter will be flush, if you don't have the lock you will be able to look down the shaft to the 3mm allen screw. Press the adjusting device down with the 3mm allen screwdriver against the spring force, turn it slightly until the adjusting screw head engages in the mixture regulating screw. Turning to the left = leaner (on/off ratio or voltage rises). Turning to the right = richer (on/off ratio or voltage drops). After each adjustment, briefly blip the throttle, make small adjustments. Running richer will make the car faster, but the only draw back to the car running rich is it will destroy your catalyic converter. A small price to pay for better performance. However too rich and the car will not idle smoothly (ever hear a race car idle).

thanks for your reply ADRIAN-MY shaft doesn't have the lock. i was wondering if your car ever gave you this problem >>> BESIDES THE FLUCTUATION- SHUTING OFF OUNCE OR TWICE WHEN COLD BEFORE STAYING ON...my 16v-86 does this every time i turn it on in the morning or after i've let it stand long enough for it to cool off.(OTHERWISE THE CAR IS IN PERFECT CONDITION).

I have had the car shut off on me in the morning when I start it up (probably due to me having the car so rich). But that doesn't happen often. Where are you located? I am in NC which doesn't get too cold. Although I have never had the car shut off while I let it idle to cool down, which I always do.

im located in CA., I THINK THE CAUSE OF THE CAR SHUTING OFF IS THAT IT IS STILL RUNNING A LITTLE BIT TO RICH.

Running too rich could cause the car to shut off on you. Since you seem to be like me, after performance, here is what I did. Set the mixture too rich and drive the car a few miles, letting it idle some to get a feel for just how rich it is. Then adjust the mixture lean bit by bit until the car idles smooth. Once I was at this point I made the car just a hair more lean. Since doing that I still have great performance and the car pures like a kitten. Good Luck.

Unless your cars are euro models, the fuel mixture is controled by the CIS-E fuel computer & the oxygen senor. When the mixture is too rich or lean for the computer to control, then you might have a problem! But when that happens most cars won't perform at all!!

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MERCEDES BENZ MASTER GUILD TECHNICIAN
ASE MASTER TECHNICIAN
27 YEARS M.B. TECH

M.B.Doc,
I guess the 16V's are different. Their is a fuel/air mixture knob right behind the air filter box. Turning to the right richens the fuel where turning to the left leans it out. This might be different than the standard 190's. If I turn the knob to far (either way) then the car can't even start. Me being after performance I made it as rich as possible and still have the car idle smooth.

You are correct, there is a fuel mixture adjustment by the fuel distributor, but the computer still corrects the fuel mixture! Yes you can change the basic setting, but that doesn't change the idle speed.
Unless you are at full throttle the fuel computer controls the mixture thru the oxygen sensor!

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MERCEDES BENZ MASTER GUILD TECHNICIAN
ASE MASTER TECHNICIAN
27 YEARS M.B. TECH

I also have a 16 valve that I had a Remus exhaust and a Bekkers big bore throttle body installed. I seem to agree the Adrian when the car needs to be richened up. I have a basic understanding about the Bosch system. Any adjustments will change the parameters,ie fuel/air at idle and fuel/air at speed. With the mods installed, the car went quite lean. My mechanic hooked up the Lambda sensor and we saw it reading close to 14 on the gauge. This was quite lean since the car was hesitating quite a bit at idle and when you pressed the gas to start off. He adjusted the idle fuel/air mixture, and now it reads about 2 on the scale. However, the car idles smoothly, +- 200 rpm at 1000 rpm. The 190 2.3 16 valve has never had a rock solid idle speed as it is a factory built race car at heart. Joe

Is the tester a Lambda Tester??? They read from 0 to 100%. 0 being rich and 100% being lean. How is the tester that "your mechanic" owns set up??

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Benzmac:
ASE CERTIFIED MASTER AUTO TECHNICIAN
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