Hi so I have a 2003 Infiniti I35, its a great car,a close sibling to the nissan maxima its partner in crime. When I first got this car it ran great, was plenty fast and the sound system kicked. I being a cheap person always used the lowest grade gas for about 5 months, then a ping developed, at first it was minor, but even after I switched to premium petro I'm getting a slight ping at 2000 rpm which can be loud/quiet . My car recently suffered from a rough first to second shift, most noticable at slow speeds when it would just dump the car into gear. But I just today replaced my mass air flow sensor from a 2003 maxima into my infiniti i35, I did the idle relearn procedure etc. My shifting now is perfect and does not at all slam me into gear to my delight. But the ping is steady and unchanged. What should I do? Could I have created a slushy tank and clogged injectors? Do I need to add octane booster? Does the 2003 maxima sensor differ from the infiniti I35 sensor?

Thanks so much I will follow with pictures on my car In a new post. Thanks so much!

 

To be honest it sounds like you have developed some carbon build up on your pistons. I recommend a great fuel system cleaner BG 44k. Don't cheap out, the rest of products are not nearly as good.

 

you probably need to use Lucas fuel injector cleaner at least three times at each fill up on your gas tank so you can really try to get the carbon build up on the valves to clean it up or at least try put a can of seafoam in your tank. it should help clean up the carbon deposit.

 

I've had good results using seafoam in the vacuum lines, it hits carbon in the Pistons pretty hard if the car is warmed up before use ( like a nice drive) and you really got to beat on it after you use seafoam to blow the carbon out. My car smoked for 5+ minutes after treatment

 

Carbon build-up. My thoughts exactly. Listen to corrective recommendations on this site. And TAKE CARE OF THAT KNOCK IMMEDIATELY BECAUSE YOU MAY BE DESTROYING THE PISTON ROD BEARINGS AS WE SPEAK.