Infiniti QX4 - Rattling noice during acceleration

That sounds like pinging. Are you using the correct octane fuel? Even if you aren't, no modern car should ping, it should just lose power when lower than specified octane fuel is used.

If you're still under warranty, take it to the dealer. If not, try using higher octane fuel before going to a mechanic. Unless, of course, the Check Engine light is on, in which case you should take it to a mechanic ASAP.

You didn't mention which year. When my old '99 was one week old I took it back and found that it needed a u-joint replaced.

It's a 98 Qx4. I've been using 87, which is probably the problem. I just filled up with 93 and put some gas treatment in and it seems to be helping it.

Is this a problem that will go away if I continue to use the correct octane?

snipped-for-privacy@nospam>

u have a infinity Qx 4? which i say cost 5grand more than the top pathfinder which i have. patty cost me around 32K. the question is why would u try to save dimes and nickles on gas when u have the money for a 36K QX4. Sorry cause someone told me this, i was complaing about the gass miliege on my pathfinder. and i got the speech. so im passing it on to you.