Isn't the primary cause for this carbon build up due to the PCV system . Considering the only fumes that enter the intake system are either air or oil vapor it would seem this is the cause. Does an oil catch can system reduce this problem.

There are some forum threads that discuss catch can mods. Unfortunately, space in the XK engine bay is at a premium and I've yet to identify a location that would work to my satisfaction. My understanding is that the container works best positioned lower than intake level but needs easy access in order to drain the collected oil.
I'm sure adding a catch can would not eliminate carbon buildup but should reduce it to some degree.
As part of the PCV system the 5.0L has an air/oil stripper but, as indicated in the catch can threads, a significant amount of oil gets past it and back into the intake stream.

I have the 3.0 where I mounted mine just in back of the passenger side cylinder head. It does collect a fair amount of where I have to check on it every few months. Pics in my album. I've studied the 5.0 and there is just no room for it there.

Also note that the truth is Not revealed! At 8.00 they show before and after injector images.... Only the "before" picture was actually taken 23 days after the "after" picture! (Ain't advertisers wonderful!)

Keeping it serious, I still believe induction cleaning with DI engines is a "must". Just funny that they screwed up the images.

Minor update.
Yesterday (one day after running the CRC treatment) I hooked up my iCarsoft LR V2.0 code reader and it showed some interesting new error codes - from memory "misfire cylinder 3", "misfire cylinder 5" and "catalytic converter fail". Not entirely sure these are the actual codes that were shown as I immediately cleared them, but close.
Anyway, went for a run this morning, car ran great, no CEL, got back and checked for codes again and all good, zero codes.
The codes were obviously triggered by the CRC treatment and again I suspect the car coughed up some carbon build up which triggered the codes.
So a heads up for those thinking of using this CRC valve cleaner, you may get some error codes!

I did too but they cleared after a few cycles.

All,

this is a very interesting thread. Thanks for starting Q&C.
I have been thinking about this catch can business. Also for the LR.
we just changed all the coils and spark plugs in the xkr and replaced the pvc valve: the originals were in good shape. They were last changed 50000 kms ago.
So I’m on the fence post on the catch can advantage. Perhaps I will just using a regularly scheduled valve and injector cleaner approach. Every year??

I wouldn't have a car without one. They catch a lot of oil.

Interesting. Those with a catch can, do you notice if you are consuming more oil between oil changes? Perhaps just feeding the catch can?
I think I will use the method of valve and injector cleaning by drilling a hole very close to the throttle body. I really dislike the amount of effort it takes to remove the entire air induction system every time I decide to clean it. Thus not using k&n filters any longer... to much oily residue in the system.

I have never had the need to add oil between oil changes. I do an oil change every 5 -10 000 kim’s.
(surprises me really at 150000 km)

If you do not use a catch can then the oil/vapor passes into the combustion chamber over the inlet valves, leaves deposits, and then gets burned.

With the 4.2 SC engine that "contaminated" mixture passes thru the cooling matrix in the charge coolers and will gradually block off the matrix probably severely restricting the effectiveness after maybe 60k miles?

So an oil catch can will prevent a good deal of it however that does not mean you use more oil with a catch can.

I rarely use emojis. That was a good one.

On this engine I have seen plenty go 200,000miles and never show any signs of needing a catch can.

When a excellent tech named Brutal was still here and being charitable, he told us he had never seen an intake valve that did not have concerning carbon.

Ok I have some questions too. I had asked this but no one replied. In choosing a hole in the rubber collar just in front of the throttle body there is nothing to lose. That rubber collar is a common wear part. But you clean the throttle plate and body in process.
If you use the vacuum line right behind the TB which is very easy to disconnect, I am guessing that no cleaner gets to clean the throttle body??

I think you are correct.

My choice on my 5.0 NA engine will be to drill a hole when I ever get around to it.

I know the 5.0 engine has better oil control than the 4.2 however I would love to hear from someone that has looked at the charge coolers on a 5.0 SC engine after 50-70k miles.

Thank you.
Really wanted to do a Y connector at the vacuum line but could get any info if the cleaner would still remain atomized.
I understand the benefits as it can be done by one person, in my case having a hand is not an issue.
I will use a drill bit the size of the straw and use blunt side to burn a hole. Plug it with a screw.

It catch's about half the can between oil changes. Have never had to add oil between changes.

Q&C do you know that hose part no ?the one that was crumbling remember ?

No mate, I would not put Jaguar rubber back on there, its commonly available. Any 6mm ID tube with some flex will be better, last longer. Its not molded.

Thanks Q&C

You're fogetting 1 important thing ... the EGR valve. When I had my throttle body elbow out, the carbon buildup and exhaust residue inside the elbow was severe - all from the EGR. How much of that exhaust affects the the intake valves? Not sure. But if it builds up there then it must build up over time on the valves also.

I speculate that a good catch can coupled with an EGR blanking system would tremendously reduce carbon build up inside your intake.

I do my oil changes @ 6000 miles. Drain the catch can @ 3000 miles. I get almost 200 mL out of the can every 6000 miles. And when doing an oil change, I am always a bit lower on oil than when I filled it. So I can safely assume the missing oil gets caught in the can, and some still gets by and gets burned.

See post #66 here:
https://www.jaguarforums.com/forum/x...-207259/page4/

I remember reading somewhere on here that the throttle body plate has a special coating, so you're probably better off not spraying cleaner on it.

Unlike me where I didn't know that and sprayed the stuff directly on the throttle body plate a year ago. Ooops!

But yeah logically if you spray cleaner downstream of the TB, the vacuum and flow won't allow any of the cleaner to get the TB.

I read that somewhere as well. Realistically how long does that special coating last tho.