I've got 3,000 miles on my M56 (non-sport model) now, and ever since new there has been a consistent shudder at around 1200-1400 rpm. It's worse when the car is just starting for the day. At first I thought it was at 45 mph, and went to work with Discount Tire and Michelin (who offered to replace all four, for free !). But the tires checked out to be perfect in every measurable way. Michelin still offered to replace them but I declined. Eventually I became convinced that the vibration is engine sourced, particularly evident about 45 mph, but actually linked to that low rpm range. The dealer said they feel nothing....said I could bring it back and they'd look again, but I had enough of a bad time buying the car and returning it for repairs that I really don't ever want to see them again.

So...does anyone have any words of wisdom ? Do other M56's have low engine speed vibrations ? Perhaps I just need to live with it ? Perhaps a poor engine mount ? My last car was a Lexus and it was, in comparison, perfect. Apart from the vibration, poor paint job and poor dealer, it seems to be an acceptable car. Any help appreciated. Thanks Doug

A tire or wheel balancing vibration is usually in the 55-60MPH range, but if you have one bad tire anything's possible. Good luck with your Infiniti dealer. I have M56X and have been complaining about a hesitation for five months. They let me drive another one and the performance seemed similar. Back to your complaint - I have no vibration so it doesn't sound normal like the dealer sometimes tries to make us think.

Thanks for your thoughts VP007. For what it's worth, my M56 seems to hesitate sometimes when given some throttle as well. I drive it in "normal" mode all the time, which may make a difference. Each time I'd get it back from the dealer after another attempt to fix delivery problems, they'd have it in "sport" mode, and I found it too jumpy. But definitely no hesitation ! The best mileage that I've seen on a highway tankful , so far, is 23 mpg, which to me is poor....I'm thinking that my vibration problem might be associated with this, such as a randomly misfiring cylinder, or similar. It really irks me that the Infiniti dealer is so bad that there's really no point in going to them with a subjective problem like this, just to get another "sorry, we see no problem" kiss-off. Ah well, life's too short to dwell on the negative. I'll keep trying to tolerate the beast for a couple of years...maybe I'll come around ! Again, thanks for the thoughts. Doug

Amazing. Two days ago the "service engine soon" light started blinking. I decided to go back to the Infiniti dealer today to try again to diagnose the low speed shudder / vibration...and the shudder was completely GONE on the 13 mile drive to the dealer ! He and I have no idea why. The service light was no longer lit at all. So after talking to the service manager, I brought the car home...vibration free. This could be the start of something good !

Did the service guys mention what caused the service light to blink and what they did to fix it?

I have a 2011 M37x so the knowledge may not apply to my car at all (I currently have no such issues) but you never know -- and besides, I'm curious.

The service manager seemed at first concerned by the blinking light, then stumped as to why it was no longer doing so. My manual says that if it is blinking, if means that there's something like and engine misfire that could damage emissions equipment...so, no rush, but go see the dealer. Which I did, but since it was no on anymore, the service manager seemed to think "no remaining issue". Incidentally, I asked him about another problem with the car that applies to all Infiniti navigation systems : the voice announcing street names has a speech impediment ! She cannot say our street name properly, or any street name that has more than two syllables. Service manager said "no fix, they're all like that". Wow ! My Lexus was not, nor Acura or Tom Tom. Curious defect.