Fri 18 Nov 2005
Posted by andy under Cars
So, enough about C#, today we are on to cars.
My year 2000 Scooby (Subaru Impreza) has been suffering from the symptoms that I seems that most of them have at some point in their lives. The symptons are inconsitent delivery of power, with flat spots in acceleration (feels like you have stepped off of the gas suddenly) and surging.
It seems that there is a long list of things that can cause these symptoms (or very similar symptoms), that include:
- failing lambda (oxygen sensors)
- failing HT (high tension) leads
- failing crank angle sensor
- failing or dirty MAF (mass air flow) sensor
- air leaks in various pipes
The most common one appears to be the last one, the MAF sensor (which measures the amount of air going into the engine). When the problems developed on my car I therefore checked the MAF sensor first.
When I pulled my MAF sensor it looked spotless, it was clean and I thought it was almost brand new. I ruled it out as a cause and plugged it back in.
Over the next month the symptoms got worse and my local Subaru dealer had a couple of failed attempts at diagnosing the problem (the ECU wasn’t reporting any fault codes, which didn’t help).
They finally fixed it this week, after having the car for three days to give them time to track it down. The main cause of the problem? Yes, you’ve guessed it, it was the MAF sensor failing.
So if I had just replaced my MAF sensor when the problems started (£60 and 10 minutes work) I could have saved myself £200 in labour costs.
So, next time something like this happens I’ll think carefully about just replacing the MAF sensor before looking at other things. Some Scooby owners replace their MAF sensor every year as a preventative measure (it seems that the MAF sensor on the “classic” Impreza is a fragile item), not sure I’ll go quite that far.