Thursday 14 February 2013

MIL On

One reason for this blog was the periodic illumination of the MIL (Malfuncion Indicator Light) on my car. Having read so many horror stories of the cost of professional diagnosis I wondered if it was within my capabilities to diagnose the cause.

Using my OBD adapter and the free Torque app for my mobile phone it was easy enough to obtain the information code being reported by the engine management computer. It was (still is) P3263. The P means the code has been generated by the Powertrain module i.e. engine control unit (ECU) rather than air bag unit etc. More about these OBD codes can be found here. However, whereas the meaning of these codes are often common to all cars and publicly available mine starts with a 3 meaning manufacturer specific! Unfortunately, it seems manufacturers still guard sets of these codes closely and so create or rather hold on to the car owners dependency on the dealer or specialist. (Although they may say the codes should only be interpreted or acted upon by personnel with specialist training).

After much, much searching the best interpretation was relating to the measurement of air flow going into the engine. More accurately a problem with the calculated amount of air compared to the measured amount and this has started a whole new chapter in learning about how the ECU uses the mass airflow meter (MAF) meter, turbo and exhaust gas recirculation valve (EGR). A very steep learning curve but I'm getting there!

To finish this post on a positive note the first part of my investigation and remedial work was to clean the EGR valve. The result was about 8 miles per gallon better fuel consumption! More on EGR's etc later.