CO check

by welding a nut for a Lambda (O2) sensor in the exhaust pipe where it sees the axhaust gases from all the cylinders... like after the collector in a header exhaust. I don't know if there is a good location on a stock exhaust for one. Then buy a heated O2 sensor (3 or 4 wire) and test wit a voltmeter. You want the meter to stay roughly around

900mV throughout the rpm range, and under load too. Run a long sender wire to the cabin where you can see the voltmeter while driving. The exhaust system should not have any leaks, that throws the o2 sensor reading off.

Jan

Can I use a Lambda sensor from a normal car? I can try to find one in a junk.

Jo=E3o

Yes you can. You need to know the color codes for the wires though, there are small variations sometimes. There are 1, 2, 3 and 4 wire sensors. 1 and 2 wire sensors are cold, and the 3 and 4 wire sensores have an internal heating element that heats the sensor up to operating temperature faster. That's what you need in a beetle, where the sensor has to be located far away from the combustion chamber, where the exhaust gases have time to cool down too much for a non-heated sensor.

The 3 wire sensors have 2 wires for the heater element (positive and negative, no polarity, connect them any way you want, the colors should be the same) and then the signal wire. This sensor gets signal ground through the exhaust pipe.

The 4 wire sensor is otherwise the same, but there's two ground wires: one for the heater and one for the signal.

Jan

Good! Now I have to find a way to install it! On the tail pipe?!? I can have a tail pipe only for that without destroying the muffler.

Jo=E3o

I found a 2 wire sensor for 52 euros... too expensive!!!

Jo=E3o

Not as expensive as a seized engine... or melted piston.... or burnt valves...

A two wire won't work properly in a bug. Need 3 or 4.

A local shop here sells 4 wire Toyota O2 sensors for 59.90eur and that's what I got. Works like a charm.

Jan

My issue is where to put it!!! They are big and restrict the tail pipe if I put it there. I have to figure out a solution. It will be only to set-up the carb. Mayybe I can find a good used on a junk

Jo=E3o