I am troubleshooting a 2005 Jaguar XJ8 Vanden Plas with the 4.2l V8. I am getting low voltage readings on both banks but do not have a check engine light, no codes stored, etc. I am trying to get this car smogged after sitting for a few years and am at a loss. I recently replaced the MAF sensor with an aftermarket unit and replaced all 8 coil packs and spark plugs. This vehicle has a badly damaged airbox that has most of the clips broken off. I seal it with a tie-down strap. I also recently changed the PCV valve assembly.

At this point, I have tried to get this vehicle smogged three times and keep getting fails for lean condition, but I can't find any air leaks. I've checked the hoses to the PCV and air inlet. I am hoping that someone might be able to clue me into where to look next. Thanks

 

There are eight gaskets inside the intake manifold.
Were what eventually fixed my 04's ongoing air leak issue.
But my check engine lite, kept coming on, car ran great.
Passed the tail pipe smog test easily

 

The repair sounds a likely source of air leaks.

Is the car going CL (closed loop)? If yes, what are the fuel trims (see the many threads for what to do)?

If no, probably a huge air leak