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Hey Guys,

My Foz has a nasty ping on boost over 2/3 throttle & seeing if anyone would know a common issue is where I could start. Has been like this since I got the car last month. Been taking it easy in the hope not to kill the engine.

First thing would be to check timing but a faulty o2 sensor could be the culprit too? Not 100% sure where to start & am avoiding taking to a mechanic.

Haven't raised boost or anything, is completely stock. Any help would be greatly appreciated.

Cheers, Simon.

What fuel are you using? And if you suspect a faulty o2 sensor check your codes.

I have seen silly things happen if knock sensors or their connectors have issues .

Obviously you would have checked oil and water levels , I have seen engines do silly things if the oil temps are high because the level was low .

02 sensor , I would have though that the system would fail safe and default to open loop and richer mixtures . Possibly disconnecting it may force this for test purposes but really need to be able to reset codes just in case .

Waste gate actuator dieing ?

I doubt the o2 sensor is causing it cos its totally ignored once the manifold pressure goes positive.

Im with disco on faulty knock sensor because if it was working, it should be preventing any knocking

Poor quality fuel could also be a culprit

Only run 98 ron fuel, still with the same result. All fluids are fresh (2000km's) and at the correct level.

Didn't even think of the fault codes, these modern cars are all new to me! From what you're saying, the knock sensor could be the culprit.

I went to check the ECU codes, only to find that the black/white plugs are not compatible. Any idea how to check the codes...see attached picture.

Jeff wrote:What fuel are you using? And if you suspect a faulty o2 sensor check your codes.

Half the time you'll find dead O2sensor but the error code doesn't show because ECM thinks its okay.

QikRX wrote:Only run 98 ron fuel, still with the same result. All fluids are fresh (2000km's) and at the correct level.

Didn't even think of the fault codes, these modern cars are all new to me! From what you're saying, the knock sensor could be the culprit.

I went to check the ECU codes, only to find that the black/white plugs are not compatible. Any idea how to check the codes...see attached picture.

Try finding the plugs possibly still have tape on them somewhere attached to the loom under there.. have another look...
Cheers
AP

Found another black plug, so thats 5 in total. Only issue is that it's yet a different type to all the others!

There appears to be no other plugs that aren't already plugged in...got right up in there this time.

Here's the 5th which was up higher.

After been thinking about the "plugs" I think this forester requires OBDII scan tool to check the codes... Most mechanics have them so worthwhile checking out for you.
Cheers
AP

That's what I'd been reading. Thanks for the help AP, I'll pop it into my mech. Hopefully it's nothing too major.

The clutch master cylinder started playing up today, i think the journey has begun again!

QikRX wrote:That's what I'd been reading. Thanks for the help AP, I'll pop it into my mech. Hopefully it's nothing too major.

The clutch master cylinder started playing up today, i think the journey has begun again!

Yeah... I was thinking, do a reset overnight (by disconnecting the battery) and go for a drive to see any differences, before you take it to the mechanic's, worth a go, sometimes its a glinch.
Cheers
AP

i would be thinking o2 sensore as well, i had what i think was some minor pinging on boost under light load untill last week when i changed the senor.

bryan