|Subject: Enging Tuner || New Question
|Sender's Name: Stuart
I have been following your articles in Total impreza and ideally would come and see you but its quite a trek, so hopefully you don\'t mind trying to help me out through your questions section.
My unmodified 2006 2.5 wrx engine (43K) makes a tapping/ticking noise when accelerating between 1500-3000 rpm with about 25-50% throttle. If I drive at a constant speed with light or little acceleration there is no noise. If I floor it the noise seems less but if I am going up a steep enough hill opening the throttle makes the sound louder even though the revs are not increasing. The car has no power problems (26.4 psi max )and sounds sweet above 3000 rpm. At idle you can not hear the noise inside the car, under the bonnet you can only hear the tappett/injectors etc which is pretty normal. Passengers say the noise is pretty hard to hear so I can only assume that its from the drivers side.
I\'ve searched loads on the forums/youtube found loads of causes, but I can\'t get to the bottom of it. I also took the car to the local subaru specialist and left it with them, but they said it was normal and was the tumbler valves. Im not sure they actually heard the noise I can though as my research suggests the tumbler valves only move around idle speeds.
I can\'t believe its a normal sound and is ruining my subaru ownership, as most of my commuting is in this rev range.
I have done the following work/tests to at least eliminate items that have been listed as possible causes.
Changed alt/air con belts.
Changed cambelt, idler pulleys and cam tensioner.
Disconnected/blocked the waste gate vacuum hose.
Disconnected the tumbler valve motor on the right bank(drivers).
Disconnected the boost solinoid valve.
Visably checked the manifold exhaust joints for leaks.
I consider the sound/symptoms to be point to pre detination, but using the RomRaider/learning view software I can see that the knock control learning table is all 0%. There are no fault codes. The only clue that something may be wrong is the AF learning table is showing between -4 to -14% in all the cells.
This clip from someone else demonstrates the sound
From your experience what would you suggest?
Hi Stuart. A take on noises. You can hear a noise, but don't know what is causing it. You investigate as much as humanly possible, taking into account such things as might be causing it. You eliminate the usual culprits, such as detonation. You now have a choice. To strip or not to strip? Often, the cost is the same when stripping to investigate as it is to strip and repair a more obvious fault. The end result is the same. A large bill. There is one possibility. A broken piston ring land, not unheard of with the 2.5 engines. The noise would be heard more in the mid range. If that's the case, it will certainly get worse, so eventually that one may come home to roost in the form of a misfire and oily smoke out of the tailpipe. You have two stark choices right now. Take it to bits, or turn the stereo up and ignore it.