Loud popping under heavy mid/heavy load + sluggish
 

A friend of mine recently bought a 2005 G35 with auto trans.

He has since replaced bank 2 cam and upstream o2 sensor, crank pos sensor and some pvc stuff.
Symptoms being experienced are a very sluggish engine, it probably won't go past 4000rpm. We didn't try to go much further than that anyway because under medium/heavy or even light load - like simply accelerating from a stop light - the engine makes a popping sound. It sounds like exhaust backfire but is coming from the engine bay.

-The car was like this before and since changing out the sensors and pvc parts there was still no improvement.
-He had the cam/crank and o2 sensor replaced because there were codes stored for them.
-Sometimes the service engine light flashes for a few seconds and then goes off.
-The car has a "cold" air intake, test pipes and duel exhaust of some sort.
-New plugs were fitted but made no change
-The timing chain was changed before he bought it, but not sure how long before.

Here's a video of what it sounds like.
I'll update the thread as I found out more information

Has anyone checked the timing lately?

Was the vehicle thoroughly checked out prior to purchase?

Telcoman

My friend bought the car just like that.
The previous owner parked the car after experiencing the popping sound and bought something else to drive. He then had to move and had to sell the G35 and so my friend bought it.

Apparently the timing chain was changed but and the car drove fine afterwards but I think we'll try and check it. Do you know if we can see the markings on the cam gears and chain just through the covers over the cam gear or does the whole front cover need to come off?