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If you want to keep your A-Class ECU/MAFS (Engine Control Unit /Mass air Flow Sensor) healthy and as a result finish up with a more responsive engine (for petrol engines only), this procedure will give you the correct method to clean it. Even with a new original filter installed and replaced at the recommended frequency, fine dust particles will still pass through the throat of the air inlet and collide with the MAFS fine glass reeds. There is no perfect automotive air filter, and fine (or even microscopic) dust particles will adhere and accumulate to the oily fumes molecules aspirated by the engine air intake, as well as from the oil sump or even from the polluted environment. Filters like the K&N and similar, that are made from oiled tissue are proved to give a better performance, when it comes to cleaning the air but there are still some ultra-fine grain particles, which will reach the MAFS and the temperature air sensor that resides just behind the MAFS. The use of low branded, cheap or sportive filters other than K&N, which uses a different tissue, can have a large fabric tram so more and more particles may reach the MAFS along with the temperature sensor, which as a result will more frequent cleaning. Those dust particles, mixed with the oil deposits adhering to the two sensors can have a corrosive sandpaper like effect, therefore keeping these sensors clean results in a more durable ECU/MAFS bearing in mind that this component is a monolithic piece and the sensors like the ECU can't be replaced alone. ANY good brand Carburettor Cleaner available at your automotive accessory market or store can be used (like the examples below), none of these will do any harm to the engine or MAFS/temperature sensors. DO NOT APPLY ANY OTHER KIND OF AUTOMOTIVE SPRAYS USED MAINLY FOR LUBRICATION (like WD-40 or similar). These will do no good, as they have no cleaning properties or effect, they will only add more oil in the process and are likely to increase the MAFS corrosion. We suggest to carry out this process; you remove the filter housing first so as to gain full access to the air intake/air inlet, visible in the photo below. The cleaning process should be undertaken with the engine stopped and in a cold condition, with the aid a small flashlight you will be able to see the MAFS through the grill, apply the cleaning agent using the tube provided with the spray can, passing through the plastic grid in the throat of the airway, apply three or four shorts sprays of approx 3 seconds each, allowing a pause of 5 seconds between each. Disregard the dirty liquid that will drain from the sensors. On starting you engine, any surplus liquid will be absorbed by the engine without causing a problem. It is imperative that the spray nozzle extension not be allowed to touch the glass reeds/sensors. Only allow the nozzle to project just through the grill thereby keeping a distance of 12mm (half inch) approx from the sensor reeds. Any physical contact with the sensor/reeds will almost certainly cause irrecoverable damage. Or alternatively, (Lofty) suggests that the job can be done by just by removing the air filter element. The depth of the throat to the grill is then 3.1/4 " or 8.5 cm, if the tube from the can was placed into this throat it is unlikely that the MAFS glass reeds could be touched, thus preventing them getting damaged. He also suggests cutting the discharge tube purchased with the can to 10cm, it will then just project through the grill but will not be long enough to touch the sensor. To spray the can will need to be held on its side; this will automatically limit the amount of fluid in each shot. With the sensors cleaned, the engine will start and run more smoothly, you should be able to achieve more miles per litre and any rough idling of the engine should have been corrected. This procedure should be undertaken twice a yearly and more frequently if you travel on very dusty roads. We at SVC have carried out this procedure to our A-Class (three cars) every two months since 2002, and in almost four years have not suffered any ECU/MAFS problems during that period. So, before considering changing such an expensive component as the ECU/MAFS, try cleaning it, following this text. If this procedure fails to fix your problem, there may be a need to replace the ECU/MAFS combined unit. SVC Global, LLC would sincerely thanks the impressive cooperation of Bert Rowe from UK (lofty) and Matthew Parsons from Australia (Mattp) in the elaboration of this text. |
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