Hi everyone,
I'm new and I did attempt a search, so please forgive me if this post exists elsewhere. Anyways, two months ago I purchased a 2009 G37x AWD Sedan with 52,000 miles on it. I have an issue where the car vibrates pretty heavily (for a luxury sedan) when stopped at a traffic light. If I put the car in neutral it will stop shaking. I posted a quick video on youtube where I attempt to show the problem at:
The throttle bodies were cleaned two days ago as an attempt to fix, but it didn't help. The car runs great otherwise. I am a little nervous about this car though because after driving it for 400 miles the check engine light came on and it required that one of the catalytic converters be replaced. I was glad to know it was under warranty... but I'm a little nervous about spending as much as I did and having issues like this. I had a 2003 G35 for 7 years and it didn't develop any issues until I got up into the 150k range.

Have any of you experienced this? I have a close friend who is a mechanic and he made a quick guess that it may be a motor mount and to contact the dealer since it'd be a pain in his *** to replace I can only nag him so much!

Thanks in advance for any advice you may have!

 

IAC valve

 

Would it still be IAC valve if it is idling fine? RPMs stay steady. Vibration gone when in park. Thanks so much for replying!

 

I just changed my intake air filters yesterday, and noticed that my car didn't vibrate as much as it did. The shifter (and steering wheel) would vibrate when at lights, I thought nothing of it. When I changed the intake filters, the vibration disappeared. Are your filters old? Mine were black and nasty.

 

Thanks for the advice - ill try that and let you know!

 

id deffinately be looking at a tranny mount if the vibration goes away when.in neutral or park. i had the same issue in my work truck and once changed all was good

 

I finally got the car fixed. I brought it to one dealer and they replaced a part (IPDM?) and said it was all set. I picked it up and it wasn't fixed at all. Then they re-programmed the ECM and told me it was all set. Sure enough it still acted the same. The worst part is the mechanic who went on the test drive wouldn't admit that it was vibrating more than it should.

So... I took it to a different dealer. Within 20 seconds the mechanic on the test drive said "that's bad" and "seems like a motor mount". I sat in the waiting area for an hour or so while they looked into it further. He came out and told me it was the AC compressor (because when you turn on the AC it gets worse). I took there word for it.

They replaced the AC compressor and sure enough it still shook. So then they replaced a motor mount on the left side which solved the issue.

I am psyched to have the car fixed. Now I am wondering if I should purchase an extended warranty. What are your thoughts? The car has 1500 miles until its out of factory warranty and I've already had a catalytic converter & motor mount replaced. I purchased the car from a friend who bid on it for me at the Southern Auto Auction in CT. When I got it there were mismatched tires which I found strange too. I should just hit the HOME button on the nav and head over to the previous owners house and ask them what the hell they did in this thing!! Yes, they left their address programmed in and I don't know why I haven't changed it yet