W126 300se o2 sensor

guy1969

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1989 300se
Trying to iron out some running rich problems and one of the things I thought about looking at was the O2 sensor however my car does not seem to have one it's a 1989 300se is this normal or am I looking in the wrong place?
 

LostKiwi

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'93 500SL-32, '01 W210 Estate E240 (RIP), 02 R230 SL500, 04 Smart Roadster Coupe, 11 R350CDi
Nope - its quite possible it doesn't have one.

As a 1989 car it most likely has mechanical fuel injection (or possibly even carburettors) so has no ability to use a Lambda sensor to control mixtures.
 

Woody123

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C200 1998 2.0
If it has electronic fuel injection, it should have an oxy sensor.
If it has a carburettor, you will have to adjust the settings of the carb to get the right fuel mix.
Carburettors work autonomously (opposed to adjusting constantly from feedback signals from sensors) so the ‘correct’ fuelling is basically down to the opinion of the mechanic.
The most feedback that old-school carburettors have is vacuum lines, so maybe one of them is blocked or split? (If it has that)


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stwat

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Your Mercedes
1989 300SE
It has Bosch KE-Jet fuel injection. If it doesn't have a cat it doesn't have an O2 sensor.
 
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guy1969

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Yes it does not seem to have a catalytic converter so it doesn't have the sensor in which case how do I adjust the air fuel mixture correctly? I have ordered new distributer cap and rotor arm,also plugs and wires. Once done I need to look at the mixture.
 

Woody123

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C200 1998 2.0
There should be various screws on the carburettor to adjust the various characteristics (idle speed, idle mixture, damper etc) check a diagram of that particular carb to find out which screw you need to tweak to alter the fuelling. I think idle fuel and idle speed are different screws though (unless my memory is failing)


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LostKiwi

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'93 500SL-32, '01 W210 Estate E240 (RIP), 02 R230 SL500, 04 Smart Roadster Coupe, 11 R350CDi
The K-jetronic injection system has numerous adjustments however you need to be careful as you can seriously affect the running of the car if you don't know what you're doing.
You also need to be sure you aren't simply adjusting something to mask a fault condition.
I'd suggest taking it to someone familiar with K-jetronic injection systems.
 

Woody123

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Oops didn’t see the post saying it’s got ktronic my bad


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