revving sounds and the engine cut

Question

I have a 2002 Subaru Forester. My engine light came on a couple of days ago and I was planning on bringing my car in to have it checked out. This evening as I was driving I felt like the car would not accelerate as well as it normally does and when I slowed down, the engine cut. I was able to immediately restart the car and decided to drive back home. While at a stop light, the engine was making a revving sound. I was able to get my car back home and do not have any problems starting it.

Any ideas on what it might be?

Answer 1

Those symptoms could well be caused by an air leak allowing unmetered air into the engine. This would cause a weak mixture when driving which could explain the lack of power and the cutting out. It would also explain the revving when stopped because idle is primarily controlled by limiting the air intake into the engine.

Check all the air pipes, including the crank case ventilation and vacuum control pipes for splits.

There are leak location methods that you can perform using some EGR cleaner or similar spray. With the engine running, you spray it near possible splits, causing it to be sucked into the intake through the split. This then acts as fuel and changes the engine revs.