Talk Morgan Forums Community The Malvern Arms Lambda Pre Cat

Hi, I think my second hand 4/4 1.8 Zetec Mog 2001 hasn't an original pre cat Lambda Sensor and I'm not so sure it's working properly.
Anyone who knows exactly which type of lambda is that? Is it from Ford? which n°? Can I order it online? where?
Thanks a lot for your suggestions.
Stefano

n.b. The numbers I found on the sensor have non sense on line:
81.17 1330 0C10

What makes you think it is not working correctly?

It will probably be a Bosch and you just have to make sure that you get one with the correct electrical connector for your car.

http://www.autopezzistore.it/autoricambi/sonda-lambda/ford

Peter, the values I can read on the ombd2 tester shift from 0 to 1 in a crazy way,
totally unpredictable. It seems a bad wire connection (fake contact) or a lambda 1 (pre cat) fault.

You would have to check with someone more expert than I but it would not surprise me if the readings you are getting are within the norm.

Don't forget that the fuel injection system works on a closed loop system. This means that the ECU checks the signal from the sensor to see if the car is running with too much fuel, rich, or too little fuel, lean. The ECU will then then adjust the fuel flow to compensate and then use the sonda lambda to check the result. The end result of this is that the mixture will constantly oscillate between slightly rich and slightly lean. The signal from the sonda lambda sensor will therefore oscillate in an apparently random manner.

Typically the voltage will be between 0.1 and 0.9 volts. The exact correct mixture would yield about 0.45 volts. In reality this perfect condition is impossible to achieve because there are too many variables, hence the oscillations.

I'll show the graph to an expert before changing the sensor but it seems really strange to see the meter goes from 0 to 1 several time in few second while throttle is at minimum idle.

Stefano. Attached is a zoomed in copy of a few seconds of one of my logs when the engine was running at zero throttle. I don't record the raw sonda lambda data but just the feedback which adjusts the percentage of fuel up or down (the green plot on the graph).

You can also see that the engine speed skips around a little as the idle control tries to keep the idle at a constant speed. The engine is actually a little hot at this moment so it is idling faster than the 950 rpm target and consequently the idle is a little uneven as it tries to adjust to the target speed.