Need some help with my 2002 XJ8 86K with '03 4.0 Engine and tranny. Put a new/used engine in the car because a engine failure. Car starts and runs but getting all the right bank misfires P0301 - P0304 plus P1316 and Restricted Performance. Changed the following items;
Cam position sensor
Coils
Mass Airflow Sensor (cleaned and changed out with the one from the old engine)
Sealed all vacuum leaks.
New Plugs
V/C gaskets
Fuel Filter
Exhaust gasket
Intake manifold gaskets

What could be taking the right bank down? O2?

 

Is the cam timing correct for that bank of cylinders on your replacement engine? They can throw fault codes if the cam timing is out by 1 tooth, so it may be worth just checking the tensioner & cam timing on that bank to eliminate any mechanical problems before looking elsewhere.

It's obviously something specific to that cylinder bank & from my own experience with O2 sensors, when these fail they don't cause a restricted performance & multiple misfires. Normally the ECU just goes into it's basic fuelling maps & throws up the check engine light, but still drives reasonably well.

How does the engine actually run? If you were misfiring on 4 cylinders out of 8, I imagine the engine would run like a pig...

 

I'm with Red:
Neither the VVT, fuel trim, nor spark advance will cause the condition you describe. That means it is unlikely the sensors are causing this condition. Unfortunately, the symptoms sound like valve timing. Other things to look at are injector wiring harness, coil harness, or some problem in the fuel feed pipe. Once you check the timing, getting a scanner on it to look at the STFT for each bank would seem like a good idea. I assume you have installed an AJ-27 engine to replace an AJ-27 engine, right?

 

Checked the timing back and forth, I was thinking the same thing. Actually advanced the timing a tooth and it ran like crap. Tensioners are good and the chain seems tight. To clarify, the car runs great and just randomly does it go into this fit of misfiring on one bank then straightens back out on it's own. Mostly on low RPM when starting out. Added a new battery and ordered a new O2 Sensor pre-cat be in tomorrow.

 

OK spent the day with the car, cleaned all electrical plugs and connections, replaced all vacuum line O-rings and checked for leaks, replaced the right side O2 sensor. Pulled the throttle body, checked connections, cleaned and replaced the gasket. Blew out the fuel pipe and checked pressure 40PSI. Started and idles like crap, runs but get restricted performance and now misfires on the other bank P0305 - P0308. Any help would be greatly appreciated.

 

Can you read STFT and LTFT with your scanner?