As the thread title says, I had a "pinging" type sound for quite a while on my I35. I just couldn't figure it out. At just 80,000 miles (owned car since 45,000 miles and sound started at about 73-75k) we've always used 91 octane (highest you can get in SoCal) always changed the oil on time with 5-30 synthetic, kept up with maintenance. After searching on here, I tried changing out the coolant even though it had been done at 60k (that made it a little quieter actually...for a little), and was ready to break down and change out the spark plugs.

But instead, I decided to take it in to the local Infiniti dealer to have it diagnosed. I have a warranty that I purchased with the car that is good until 95k or so. I was worried about this because:

1) I was afraid they'd give me a big, bad engine malfunction diagnosis but wouldn't honor the warranty because I didn't go to them for the work (I know about Magnusson Moss but still...)

2) I was worried they'd say I needed like spark plugs or something simple that I could do but would be pushy about doing it themselves since they had the car.

Turns out that their diagnosis was worn out crank shaft bearings. They would have to be replaced. I also had a "hard start when warm" issue that would cause the car to die upon warm startup unless you gently had your foot on the gas pedal. That was diagnosed as bad injectors on one of the banks.

My warranty had me on the hook for $100....they did all of the crank shaft bearings, replaced the valve cover gaskets, replaced 3 fuel injectors, and replaced the idler pulley (that they found was just starting to make noise)...$2500 worth of work (most of it labor)...cost me $100. They honored their warranty but also treated me like a customer wants to be treated. Great experience! The Acura dealership a little down the road has NEVER treated me like this...hence why I only go there when I am desperate and need a part right away. Big props to Infiniti. They even put me in a loaner G25 for the 7-8 days it took them to do the work (I like my I35 better to be honest).

Point of all this being that I wanted to have it archived that my pinging turned out to be an internal issue, the fuel injector issue, but also that there are truly some good dealers out there. Of course for the price, seems that they should be treating their customers as such (take note Acura!).