Air flow meter and lambda sensor problems.

Hi All

I wonder if you can help with this problem my car has been recently diagnosed as having. Car details are Alfa 166 twin spark (2001 model- 22800 miles approx) I will briefly explain what has happened to date:

The problem has been over approx 4-weeks that the car has intermittently felt as if it was being starved of fuel on light throttle and felt as if it was surging. I put some Redex into the tank hoping it could be as simple as that and also checked there were no air leaks but although some days it ran fine it was still not 100%. In the last few days the onboard diagnostic light came and it was regularly cutting out when pulling up so I booked it into Alfa. Alfa have connected up their diagnostics equipment and advised that the Lambda 1 sensor is showing high resistance on the heater Lambda 2 sensor is operating below the lower limit. There is also an error with the air flow meter. To replace these items is £422 which includes 1.5 hours labour. I was hoping that there would be some way of perhaps repairing the air flow meter or are they all non-serviceable items. Are there any other suppliers of these parts. Car was just put through an MOT with Alfa approx 6-weeks ago. I can't understand why all these items would all fail simultaneously !

Any comments would be much appreciated.

Thanks all

You can clean your MAF....

Here is a quick guide...

Remove the MAF - undo the metal clips with a pair of small pliers or lever off with small screwdriver, undo the cable tie which keeps the connector cable tidy to the air duct.and then the connector remove the MAF.

There are 2 TX secrurits screws that clamps the sensor to the MAF body...these can be undone with pliers as they are not to tight.

Pull the sensor head out and stick the MAF body a bowl of luke warm water and slosh about...use a sponge to clean the inside of the MAF body but do not touch the Mesh. then put back in the bowl and leave for about 20 Mins...

To clean the sensor head you need anti-static cleaner from Maplin or any radio hobby store..

Spray liberally all over the head......

You will see a channel in the sensor head, and will notice a wire running inside....you can clean this with a cotton swab with cleaner applied.....don't go to mad just apply gentle pressure.

At the side of the sensor is a metal plate within another channel...you can clean this using the cleaner and some tissue, wedge it in the grove and slide in and out....you can use a small screwdriver to exert more pressure to clean the plate and the edges.

The sensor heads..electonics is sealed so dont worry too much...but still be carefull.

When this is done....rinse the sensor head under luke warm running water from the tap and just cover the top part of the head where you have cleaned...

when done remove the MAF body that was soaking, test the mesh for cleaness with a cotton swab, if still dirty use the anti-static cleaner to clean more..and re wash in luke warm water.

Lay both the sensor and the MAF body...on a tea towel on a radiater to dry naturally...

Re-Fit the MAF all back together and put back on the car.

Your MAF should be now as good as new....


Chris

Google is sometimes a savior

Found these direction with pictures. Haven't done it yet but please someone comment if something is wrong (exept the beer ofcourse)

http://images.google.is/imgres?imgur... r%3D%26sa%3DG

You can check the lambda sensors using the info on this site.........

http://www.picotech.com/auto/lambda_sensor.html

the instructions are quite easy and you can also identify which sensors you have. Takes 5 mins approx.

http://www.alfa156.net/tech/MAFguide/03.JPG
Look at this picture - you see the bendy rubber pipe between the throttle body and air filter - where it says unscrew? Well take this tube off and see if its split underneath in the concertina part. The oil breather pipe dumps oil here and it rots the rubber tubing, giving the running symptoms you describe.

Test the MAF by disconnecting it - problem same then MAF shot or worse - MAF probably OK, try a clean though.

MAF is most likely, if thats duff then it may upset the lambda sensors anyway. A MAF can be picked up for £80, takes 10 mins to change. Lambda sensors cost same but there are two or three and more difficult to change. Process of elimination mate.

Thank you all for this very useful and comprehensive info. I will check out the MAF/sensors and let you all know how I get on.

Cheers
Pete