Why is my BRZ idling so rough?
 

Long-time 2013 BRZ owner here. Car is about 5 year old with 37k miles. One thing I am concerned about it that the car idles petty rough, especially when it is still cold. I feel like the connection rods has a bad bearing (of course I don't really know). It has been this way since new and I have a pretty peaceful 5 years now. Should I be concerned that it is an exploding bomb? I still have a couple of month drive drain warranty. Not sure whether I should take it to a dealer to have a look.



Any ideas? Thanks.

There are 1,000 things that could cause it to "run rough". Need a pile more info or even better a video to even make even a remote long shot guess (although there will probably be loads of people that will be happy to tell you what is wrong). If it has done it since new I highly doubt that it is rod bearings or it would have blown long ago.

Hasn't it been to a dealer already? It has 37k on it.

What lantana and tcoat said^

So many things can cause a rough idle condition. Do you have any mods?

Either way you said it yourself go to the dealer while it still has time left under warranty and get it checked out, if they don't find anything take it to another Subaru dealer if possible to confirm. Also 37k miles is pretty low for a 5 year old BRZ which is pretty cool.

Have you tried turning the "idle roughness adjustment screw?"

factory ghost cam

It is quite hard to describe the feeling. I kind of suspect that it is a Subaru design issue. Piston and connecting rod of a Boxer should move in a roughly horizontal plane. But I feel that while it is idling, there are some additional vibration on the vertical plane. I was hoping that someone else who experienced it can explain to me what is going on. But scratch that.

@qqzj There is a reason that 4-cyl Boxer engines have rough idle. It is on their inherent design, because of the firing order LLRR or RRLL.

So would a 6cyl boxer engine be more in balance?
LRL+RLR or RLR+LRL

what you mean with rough? that the rpm oscillate or that the car vibrates? it rpm oscillate i m pretty convinced it a becayse the stock tune that add PI already starting from 0.2 of engine load and PI and DI are never match-scaled properly
i fixer the rpm oscillating in every tune I did removing PI untill 0.4 engine load and reducing a bit port scalar from 228 to 222 or 224

Yes it should be more in balance:

https://youtu.be/QKPPFigKXzE?t=453

Yea the stock tune has a garbage idle, especially on the early cars.

Find someone with another one and see how it compares to yours. When I first started out with this car that's what I did every time I heard a weird noise or something.

Yup, 2013 tune sucks OP needs an OFT to slightly raise your idle.