2001 QX4 Afterfires even with Catalytic converter disconnect

[mwatson1445]

I have a 2001 Infinity QX4 that blew a head Gasket. Since I actually drove this baby off the lot brand new and my kids grew up in it I admit is has some personal value to me With that I swapped out the engine because the old engine had 250K miles on it and replaced with a motor with only 85K miles (so they say).

Car starts fine. Starts right up! But has a rough idle and I get an after-fire in the Catalytic converter on the Passenger side I actually disconnected the Catalytic converter and I still get the bright blue flame coming out with VERY loud Pop!.
The Cat problem always stays on the Passenger side. Tried disconnecting the Mass Airflow Sensor No help. Cleaned the MAS still has the backfire. I will replace all Catalytic's but I am worried if I do not fix the after-fire it will just ruin the new Cat. Is it possible to adjust the timing? I saw there is crank position sensor that may cause a problem, has anyone seen this? Not sure how to adjust timing if that is the issue because the car is all computerized.... Changed the ignition coils and no help. Everyone can laugh at my ignorance after I fix this thing!
You guys are the GOD's please throw down your wisdom.... THANK YOU SO MUCH

Mike

[ezb57e]

Not sure I understand your problem.
Are you running the engine with no exhaust on it? Do you mean afterburning?
If it is on only one bank, early on in any diagnosis I would want to do a compression check and see that the exhaust valves are sealing.
Problems that are isolated to one cylinder or one bank aren't usually caused by components that govern all the cylinders such as a MAF, crank sensor, fuel pump etc.
Good luck.

[rwardell]

^+1

also if you can take it to a shop with a scan tool, look at the fuel trim for L/R banks, you may have a sticky injector dumping way to much fuel in one of the cylinders . these odd problems are common with junkyard stuff as you never know how long its been sitting on a shelf. or worse yet in the yard with the hood up...