It might also be the knock sensors are on their way out. They can be going bad without throwing a code.

I replaced my cats and o2 sensors last year and my driveability was much improved, but I would still get some pinging noises upon light acceleration. I had the opportunity recently to gain access to the knock sensors so I decided to replace them since they were original. I discovered that one of the wires had begun to corrode...but still no CEL to warn me about it.

The old sensors were definitely retarding my timing and bogging down my engine performance. My butt dyno tells me that I have finally regained all my original power (and maybe a bit extra with my exhaust mods) with ZERO pinging. I frequently find myself doing 90 mph without realizing. Acceleration is effortless and throttle response is better than I can ever remember it being.

Moral of the story...if your knock sensors have over 100k miles on them, replace them even if they're not throwing codes.

 

Hey everybody! So I've finally managed to collect all my needed parts for this job, just reaching out for some knowledge and wisdom!

Here are my parts:


New knock sensor direct from Coventry North JLR (AJ89189), intake manifold gaskets from RockAuto (MS19423), and last but not least a new set of plenum gaskets (AP78702ATX)

The plenum gaskets I'm not 100% satisfied with, they seem to lack a certain amount of quality. I can provide individual images if need be. Nothing is damaged however.

So beyond sockets, ratchets and your standard tools is there anything I should get for this job? Hoping to complete it over the weekend and see if I can't get this rattle dealt with. I apologize for the quality of the picture, phone camera FTW

PS: was also searching the net and found a fellow who seems to have had the same sort of noise from his jag:

http://aftermarketgarage.com/jaguar-xj8-x350-engine-clatter-on-heavy-acceleration/

The sound clips are pretty awesome in general. These engines sound lethal when you're in there with it!

 

So I've finally gotten the time to get started on replacing my sensors and gaskets, was cruising along fairly well until this:

I've removed the throttle body (but not the elbow) and associated hoses, disconnected the hoses to and from the EGR, unbolted the EGR from the side of the elbow (did not remove it entirely), loosened or removed the wiring harness brackets from the sides, and removed the 5 bolts on either side of the manifold but she won't budge. Fuel rail has been left in place.

I've read through other threads like slmskr's which is the exact same removal process being that both cars in question are 4.2L X350's, but I can't seem to get her to go. Is there something I'm missing? Any help would be greatly appreciated!

EDIT: did some feeling around and it seems there are six upward driving Torx head bolts that are keeping it held to the lower portion of the manifold... three along either side, just below the fuel rail height. Do these need to be removed??

I have also removed the Torx bolts from the fuel rail but am not having luck pulling it upwards. Injector electrical connections are unplugged, but there are what seem like u clips on them from the plastic head to the fuel rail. How are / do these need to be removed to uninstall the injector/rail assembly?

Sorry for the mess in the picture, trying to keep dirt out of things and only disconnect what I absolutely have to, shifting things instead of removing where possible

 

If you look at the photos in post #8 from my old thread https://www.jaguarforums.com/forum/x...on-s-c-149873/ you'll see the torx bits stay in place. There are only 10 bolts holding the intake to the block. Once these are out it shouldn't really stick, but mine had the original metal gaskets. If yours was off before and has fiber gaskets it might just be stuck from that.

Also don't yank the intake up, the map sensor and brake booster connection are on the bottom of the intake.