One thing I did come across, but not sure if there is anything to it: Saw some comments suggesting that having hoses involved with the new catch can setup that are significantly longer and wider in diameter than the original smaller hoses in the stock PCV COULD possibly cause the PCV setup to now run out of spec, and the oil separator in the PCV stock setup might not work as good as it originally did? Not sure if this is fact, but I saw that suggested. So, the suggestion was, how much of the collection in the catch can is due to the stock setup being undermined in this way?

So much info out there, and so hard to know what is fact and fiction. A lot of this stuff is about going with what ya feel comfortable with based on taking a large cross-section of info.

 

This was also quite an interesting video. This guy, despite bringing into question the value of catch cans, suggested that this can used by ER9240 is a decent one.

Part of his message was that, when you consider that there are 2 other inputs to the intake build up problem that catch cans cannot help with, it does ask a fair question around whether the added maintenance and potential risks of installing one are worth it.

Read about a few accounts where the catch can froze and blew out rings and main seals. Read about another account where, despite constantly checking the filter and emptying the can, something weird happened with the baffle/filter in it…Too much pressure built up in the crank case and it caused a bunch of problems for him. These are “added risk”-type examples. But, I don’t know, I tend to generally think that if you are on top of things the odds of something like this happening would be unlikely? I wouldn’t even consider using one in freezing temps personally, summer-only driving.

EGR inputs to the buildup problem, as I understand it, are an equal or worse contributor. There is also contribution coming from the combustion chamber itself back up through to the intake side as well as the valve opens and closes.

 

I’ll give my final two cents.

- Gummed up and/or heavily carbonized intake valves can cause a rough idle condition by disturbing/restricting air flow into the combustion chamber - often without a check engine light.

- Catch cans work very well for forced induction, direct injected engines (this platform) to prevent excessive oil being sucked back into the engine via the PCV system which causes gummed up/carbonized valves.

- Catch cans are not a “set it and forget” item and need to be monitored/maintained.

- Catch cans need to be set up correctly (correct diameter tubing, correct routing, etc) to prevent problems with the PCV system. Our systems are very straightforward and make for an easy set up on the passenger side (right side) of the engine.

- I’m a shade tree mechanic with extensive experience working on cars over the past 30 years. I’m not an expert or JLR mechanic. Take what I say at face value and do your own research - but I’ve never made a vehicle any worse than when I got it… lol.

 

I think ER9240 posted what I "think" is going on with my XJR.
- Gummed up and/or heavily carbonized intake valves can cause a rough idle condition by disturbing/restricting air flow into the combustion chamber - often without a check engine light.

I have a a bit of a lumpy idle that feels a bit off. Worse when it's cold out. Very minor and I maybe chasing a ghost here too! It sorted felt like what happened when my PCV diaphragms split. At first it was just a slight wobble at idle. Then it got worse and finally threw a check engine light with PCV codes. Now I knew what to do. But no codes now.

One downside is I wish they had designed the can so it was easier to empty. Some kind of screw off top with an O-ring separate from the plumbing. Now all the hoses need to be removed and then you can unscrew the top. A quick drain idea would be helpful.
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