Hi my 2004 g35 coupe is shaking when idle (when parked or waiting at a red light). My spark plugs were shot i just changed them today hoping it would solve my problem but it didn't. Not sure what else it could be, plz help a fellow infiniti driver 😅

 

Vacuum leak?

 

Get it up on a lift, start the motor, look for anything moving that SHOULDNT be moving. If you're having a hard time finding a lift for a reasonable price you can usually work out a deal with a local lube shop that has a pit. Sometimes it's as simple as a broken exhaust hanger, sometimes it's a worn bushing, sometimes it's a broken motor/transmission mount. Get someone to sit in your vehicle and shift from park-reverse-drive-reverse-park-rinse-repeat, it should be pretty obvious what's broken because nothing should be moving at all when you do that.

Does it shake in park or only while in gear? Usually if it shakes only while in gear then you're looking for a worn/broken engine or transmission mount.

 

Hey man thanks for ur help. It's shaking in both parking and drive, but as soon as i press the gas or let go of the brake in drive, it stop shaking and drives smoothly. My mechanic said i needed a new catalytic converter for my exhaust, can this be the cause of the problem?

 

Without actually seeing the cat it's hard to say, you can remove it, look inside, if the honeycomb looking grid inside has melted spots on it then yes it needs to be replaced but I would get a second opinion unless you have a lot of faith that this mechanic to not screw you over replacing stuff that isn't actually tested.

You can always ask to have him show you WHY the cat is bad, there will be physical evidence, don't rely on "magical gut feelings" when it comes to replacing parts on a car, ALWAYS ask to have them show you the details, a reputable mechanic will hide nothing.

 

He showded me by gently banging a hammer on it and u could hear something loose insde. On both sides. Also, when i accelate u can hear something rattling from the exhaust i'm 99% sure its from that

 

Ok sounds legitimate, I would highly recommend a quality high flow cat like the one from Fast Intentions. It will cost you about the same amount, maybe a tad more than an OEM unit but it frees up the most restrictive point in the exhaust system, has a solid reputation, and adds power.

 

Hey Certified, any chance you got this issue resolved? I'm having a similar issue with my 03 G coupe and I think it's the Cat as well... When you're at an idle and it shakes, does it kinda feel like someone lightly tapped your car from behind? That's what it feels like to me. And once your parked and turn the car off, is there a tapping noise from your exhaust near the Cat? Mine does and that's what leads me to believe it's the Cat... Please let me know if it's the same and if you got it resolved.