Liberty GT MY05 Intermittent rough idle

[Nosf3ratu]

Hi,
First post here so please be patient!

My MY05 Liberty GT is experiencing an intermittent or wavering rough idle when in gear or neutral, most noticeable when at the lights when the car is warm. I purchased the car a little while ago and the idle issue started a few weeks after that. Basically, the revs will drop down to around 500 and the car will shudder like it wants to stall, then there first a sharp sucking noise followed by a pinging sound from the engine and the revs will surge to 1000rpm for a couple of seconds. This repeats every 15 seconds or so.

I had a read through snaza's thread here viewtopic.php?f=17&t=13374 and have checked the VVT angles through FreeSSM but they are both showing 0 degrees. I took it in to my local Subaru specialist and they were unable to diagnose the problem other than a small oil sweat which I was already aware of. I'm pretty inexperienced which cars in general and am yet to run RomRaider to thoroughly check it out but any advice would be appreciated.

I've uploaded a video of the engine idling and dropping rpm with the pinging sound. You can hear it pretty clearly around the 14s and 35s mark http://youtu.be/Bdxs4C6T70M

Cheers!

[zch91]

Hey mate. You need a new O2 sensor.

If you scroll down near the bottom of this section of the forum (2.0T) you'll find an identical thread by me from a few months ago.

Here's the link:

viewtopic.php?f=17&t=22622

[NRV155]

Sounds like it. Way too common. After you buy a new one, keep some spare cash for the next sensor to go.

[Nosf3ratu]

Thanks guys.

I'll pick one up from here http://www.rhdjapan.com/subaru-oem-air- ... -2006.html

I guess it's not a bad idea to grab two now, assuming this sensor will suit both front and rear?

[maj]

Double checked the MAP sensor is hooked up? Don't have any a vacuum leak anywhere in the intake manifold?

Sounds way too similar the issue I was having where it would only present itself once the engine had warmed, turned out the vac line going to the MAP sensor had cracked and fallen off. Beware of how much boost its getting if its the case!

It could still be a front O2 sensor issue, but the MAP sensor issue looks similar when you check with Learning View (i.e. really rich at lower RPM)