Stupid ? What does a Lambda control when no O2 sensor

[mespe]

Trying to figure out my new 1980 280SLC Euro.

I find NO markings for a Catalyst
No Emissions Label
No EGR, I don't see a Catalytic converter.
The car has factory headers, two pipes going to a rectangular, what I'm guessing to be a muffler, with two pipes out of it as well.
Car has a jetronic module, where some wires melted and a previous owner hooked up 7 wires going to it.
I have been unable to find a pinout for the jetronic unit, so I don't know if everything that is supposed to be hooked up is hooked up.
The connector going to the jetronic is missing, but I have access to one from a volvo.

So far I have determined that two of the wires from the jetronic go to the frequency valve, and then there's +12V, Ground, but there are a total of 7 wires hooked up to it.
Hopefully when I get the connector and harness from the volvo, I will be able to figure a little more out, but in the mean time.

What does a jetronic do, if there is no catalyst and no O2 sensor?


Not to sound completely ignorant, my guess is nothing, and that the system is running open loop and I have no control over the Lambda operation.

[97 SL320]

Early 80's SAABs had this system as well. Lambda isn't about a cat converter, it is about fuel mixture control. There should be a spot for the oxygen sensor otherwise there can't be any fuel control feedback.

With the oxygen sensor unplugged the system will run as some middle fuel mixture.

[mespe]

There are 2 plugged holes in the exhaust headers, but those would have been before any catalyst. ( I thought all US cars had cat's since the mid 70's)

I kinda learned lambda working on a 1988 190e. So I "kinda" know how it's supposed to work, with feedback from the O2 sensors controlling the air/fuel mixture.

[abiby]

IIRC Kjet with lambda began with the '80 model in the US. Prior models didn't have an O2 sensor.

However, I'm not sure when or if it was ever introduced to the 107 euro models.

[meltedpanda]

the sensors would be placed pre - cat IIRC

[mespe]

We'll continue after I can find someone else with a 1980 280SLC. should be TOO difficult

Maybe a 280SE or 280E of 1980 vintage, fuel injected, not carbuerated.

[rowdie]

I have an unmolested '81 280SL. No Lambda, frequency valve, O2 sensor or cats.
Yours could have a USifukated system of some sort.

The '85 280SL had all of them. '83 did not. Not sure about '84. Should know by the end of the week.

[mespe]

Well, now I'm totally confused. I went to look at a 1980 280te grey market wagon. Same fuel injected engine, alright, with me so far? So I look for the O2 sensor, wait, there are no plugged holes in the exhaust manifold (like mine) and no O2 sensor either.

I head over to the other side of the engine compartment, looking under the air filter, What? NO frequency valve? Thoroughly confused, I went to the passenger side kick panel and WHAT, NO K-Jettronic???
Which means no wire harness for me.

The owner, had a nice 450SL and 300D parked in the garage, nearly showroom condition, seriously, those two cars belong in a musuem.

At anyrate, I ponted out to the owner that the Mercedes emblem on the hatch is upside down, he never noticed, I also pointed out that I was interested in the car for the harness.

So do I need a Lambda? I think it would be nice to be as original as possible.
How can a Lambda unit function without an O2 sensor? Or is it there just to provide the frequency valve the 60/40 duty cycle?

I understand that a lambda unit will adjust the air/fuel ratio to maintain 14.5:1 throughout all driving conditions. So that means peak power and efficiency.

Oh, the owner gave me a phone number to his mechanic that worked for Mercedes (the company) as a goto guy. So I'm going to have to call him up.