Under certain high engine load driving conditions, engine combustion may occur prior to spark ignition resulting in elevated cylinder temperatures and pressures.
2015 wrx exhaust sound software#
Subaru has developed a modification to the Engine Control Module (ECM) software logic due to a possible pre-ignition issue on certain 2015 model year WRX vehicles and certain 20 model year 2.0XT Forester vehicles, equipped with a 2.0 liter turbocharged engine. There is a TSB/recall for 2015 Subarus with the 2.0L FA engine for pre-ignition causing the noise you otherwise seem to be experiencing. Hm, I am thrown off by your mention of the clutch, throw-out bearing and deceleration notes, but I figure this is worth mentioning as it otherwise fits the bill. Since the ticking is independent of engine or wheel speed, you are probably safe in assuming it isn't one of the other bearings elsewhere on the vehicle (wheel bearing, diff bearing, pulley bearings, etc.) You would expect those to modulate directly with engine and/or wheel speed. I wouldn't know where to begin chasing down a failed bearing inside a transmission, and since its under warranty, you shouldn't have to. If it isn't the throwout bearing, it could be one of the numerous other transmission bearings further down the line. Here is a link to a WRX forum where a bunch of people have failed throwout bearings: Given everything you wrote here, and the well known throwout bearing issue, that seems the most likely candidate. The already mentioned throwout bearing is a possibility, especially with Subarus. Given that the issue vanishes "immediately" upon pressing the clutch, I would guess that the problem lies somewhere in the transmission or its linkages. Took it to the dealer on 28 Nov, they looked at it and are replacing the clutch and throwout bearing. Engine temperature doesn't seem to matter, it made the noise immediately after starting.It immediately vanishes when disengaging the clutch (pushing down on the clutch pedal), but returns when the clutch is re-engaged.Once it started making the noise, it didn't stop until I parked (about 10 minutes of city driving).I heard it this morning on my way to work (after about 45 minutes of highway driving).I can't hear it at idle but can occasionally hear it when the car is parked and revved up then allowed to spin down (i.e.: accelerator flat on the floor from idle to 4k RPM, then fully released).I can hear it for the following 60sec or so of decelerating or coasting.It is drowned out by engine and exhaust noise above that point.I can hear it when cruising/accelerating around 2K-4K RPM.It only manifests itself during/shortly after the engine has been under more than a slight load (enough load that the turbo is creating positive pressure in the intake i.e.