1999 XJ8L with the 4 lt

I get those two codes. Then sometimes I get code 306.
Then clear them, and the next time I might get code 307.
Then sometimes I might get code 308.
When I get the cylinder misfire codes, I always get the code 300 and 1316 with it.
I have thrown new plugs, coils, injectors, upper chain tentioners, Mass air flow sensor, O2 sensors, but I keep getting these codes for bank 2 showing up.
At an idle the car runs like it is loping. could be a miss. But when I give the car moderate throttle, it runs just fine. then at cruising speeds of like 55 and above with (car doing a steady speed above 50) the car starts missing bad, but it wont throw a cylinder code at that time. just the code 300B and 1316. Only time I can get it to set a cylinder code is to drive it around town at 30 and below.
Thoughts anyone? If the main chain tentioner on the bank 2 is toast, would these be the symptons for this?
This is driving me nuts and I am going broke figuring this out.

edited: Car is Fixed!

 

P1316 is injectors or IDM (injector drive module), maybe you have a bad connection there. That would probably cause the random misfires you are getting.

 

P1316 on a Jaguar AJ27 engine is :
Ignition module / coil failure Misfire rate catalyst damage- A bank (1)

Possible Causes:
Cylinder compression low
Worn camshaft / broken valve spring(s)
Fuel delivery pressure (low / high)
Fuel injector(s) blocked / leaking
Fuel injector(s) continuously open
Fuel contamination
Fuel injector circuit fault(s) (Injector DTCs also flagged)
Spark plug failure / fouled / incorrect gap
ECM to ignition module primary circuit fault(s) (Cylinder misfire detected DTC also flagged)
Ignition module ground circuit open circuit, high resistance

Since you are experiencing misfires on several cylinders, rule out the one cylinder root causes. That leaves the possibility that the coil circuit is loosing its power connection, possibility of a mistimed cam, or even a fuel injector intermittent circuit fault.

I would sure look at charting the STFT while the problem is occurring to see if I could tell what was going on.

 

Thanks and yeah, the timing chain tensioner (upper left side) was changed because the top came off. It didnt screw up but it might have slipped a tooth. The short term for bank 2 is within 10% from 0. about 6% negative at idle. Bank 1 is out of wack now that I put a new O2 on that side. its 25% to the plus. But the misfires are happening on bank 2. Thats the strange part. Thanks for the info. will tear into the cam alignment this weekend and have to get another O2 for bank one. Before replacing that o2, i alwys had positive stft of 8% average at ilde.
The IDM, thats part of the computer? or is it a separate module?

 

Actually, your car should be an AJ27 engine which has no IDM modules. The amplifiers are integral to each coil.

 

thanks, the coils are 4 wire coils so that makes sense.

 

CURED!!! when my problems originally happened, the drivers side upper cam tensioner had broke the plastic guide off it. Car still ran, but was missing. I started replacing stuff before I replaced that tensioner awhile back, I did like the videos showed about keeping the chain strapped to the gears and changed the tensioner. Today I pulled the valve cover and decided to make sure the cams were lined up properly, The exhaust cam was off one tooth! woohoo!!! Car runs like a million dollars now! even had it up to 165 mph on a test drive with more gas pedal left to go!
Thanks everyone for your tips and help. moral of story, even if the tensioner did not break off, when replacing it, dont do the guy in the video on youtube, make sure the cams flat spots are lined up first!