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MOGAS and Lambda Sensor

I put a Lambda sensor and an indicator into our Lycoming powered plane which has a MOGAS STC. Leaning now takes less tan 2 seconds. I simply bring the mixture back to L=0.89 for best power or to 1.1 for best economy. Then it takes sup to 15 seconds for the EGT s to stabilize….I apprecitate the quick leaning especially when taking offf in the mountains on short strips. Till now, there was only guessing how to set the mixture, With the Lambda sensor pest power is set almost instantly. I positioned the sensor on the exhaus, sot that it can be fast removable, in case that the plane gets AVGAS. In this case I can unscrew the sensor and plug the hole without removing the cowl. Lamda sensors do not like lead.

EDTQ / Sarentino

Actually, searching for “lead tolerant O2 sensor” finds quite a bit of information, too.

LKBU (near Prague), Czech Republic

Yes – how did the O2 sensor in my Toyota Celica Mk 2 work, with leaded petrol which I ran in on for 15 years? That issue must have been solved somehow.

Shoreham EGKA, United Kingdom


Your Celica did not have a wideband o2 sensor. It could not sense 02 though the whole lanbda range. he newer technology with wideband sensors can do that, but they do not like lead.

EDTQ / Sarentino

Where exactly in the exhaust did you put the sensor? What allowances are there for the fact that each cylinder may be different? I realise that it is normal practice in automotive installations to install the sensor downstream of the collector but most Lycoming exhaust systems do not have a collector. (Well, I suppose you could argue that they do in fact have two separate collectors but I’m sure you get my drift.)

Forever learning

I have a 4 in, one out muffler. The sensor is mounted downstream from the muffler in the exhaust outlet close to the muffler. This indication gives me an " Overall " status of the exhaust gases. My CGR 50 Scanner from EI, shows each Cylinder in CHT and EGT. If one value would go ballistic, I will be able to see that, which jug is not doing fine.

EDTQ / Sarentino

That makes more sense now!

Forever learning

I think It’s easy to get confused on this subject. Other than the wide band versus narrow band sensor issues, there is the issue that the original narrow band O2 sensor (and feedback) were introduced largely because they made catalytic converters practical. Catalytic converters don’t like lead, and they were in turn why unleaded fuel was introduced in the mid-70s. Then in some markets, where car regulations didn’t require catalytic converters until much later, the same cars were sold with O2 feedback but using leaded fuel.

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