Mitsubishi Carisma 1.8 GDI 2001 model - Faulty lambda sensor

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Tue 30 Sep 2014 23:09
Mitsubishi Carisma 1.8 GDI 2001 model - Faulty lambda sensor - Big Neily
Is it possible to remove the lambda sensor and clean it, to stop my carisma from idling at low speeds, and cutting out.
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Tue 30 Sep 2014 23:41
Mitsubishi Carisma 1.8 GDI 2001 model - Faulty lambda sensor - The-Mechanic

You'll probably find its the throttle body causing poor idling on these engines. Its a well documented failing on the GDI Mitsi's.

The lambda sensor only senses the gasses coming out and tells the ECU to adjust the fuelling accordingly. If the throttle body is worn, it cannot apply the correct mixture and you get a lambda related error.

By all means you can try cleaning the sensor. Its not advisable though as you can damage it, and you'll probably find it is the actual throttle body after all.

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Wed 1 Oct 2014 09:54
Mitsubishi Carisma 1.8 GDI 2001 model - Faulty lambda sensor - Railroad.
Lambda sensor heater coils are the most common reasons for failure, but they usually generate a code relating to O2 sensor heater circuit. The operation of the sensor itself can be tested by connecting a voltmeter to the sensor signal wire and earth, or more easily by using a scantool. Run the engine and and when it's warm observe the voltage which should be continuosly ranging between 0.1v and 0.9v as the system changes from rich to lean and back again. The system is known as closed loop. A rich mixture consumes more oxygen than a lean one and so there will be a greater difference between oxygen inside the exhaust than outside, and so a richer mixture will be shown by a higher voltage, and a lean mixture as a lower voltage. To test the sensor gently crimp the fuel return pipe (if possible) to restrict the path of fuel back to the tank. This will force the engine to run richer. The O2 sensor voltage will now be higher than before because if this. Beware though that this will only be the case for a short while because the ECU will soon start to make corrections. The point is though if you see an alteration in sensor voltage in line with whatever you do to change the running state of the engine you know the sensor is working properly.
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Wed 1 Oct 2014 13:40
Mitsubishi Carisma 1.8 GDI 2001 model - Faulty lambda sensor - Cyd

Some cars suffer from the throttle body and butterfly gunking up, which can cause idling problems. Have a look and if it is then give it a clean. Carb cleaner can be had from Toolstation for £3 ish. Use rag and an old toothbrush and spray the cleaner on these first - don't swamp the throttle body.

If, as Mech suspects, it has mechanical wear then more drastic measures are required. Air leaks around the butterfly shaft can cause the kind of problem you describe (I'm assumng this is what is being alluded to). I've no idea if anyone offers a rebuild service for these. I have however had some success with the odd diy rebuild by packing plenty of moly grease around the shaft and seals. But this will need repeating sooner or later. Maybe a low mileage second hand unit would be better bet.

However, since you specifically asked about the lambda sensor, do you have some diagnosis which has pointed at this as the fault?

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