DanfZX14

In OEM quantities it would be significantly less then aftermarket which isn't that expensive to begin with.

tenspeed

It could be a couple of reasons. A catch can may not be efficient enough to justify the cost or most of the engines make it past the warranty period without it.

As with any modification, do your homework. There are many direct injection and valve coking videos on YouTube. Sit through a few and make an educated decision. If you're the type that keeps cars for the long haul, a catch can could be for you. You can also count on a valve stem cleaning at some point because a catch can doesn't eliminate all engine oil vapors.

DanfZX14

Yeah I'm guessing I'm in for a cleaning at some point down the line after the warranty runs out.

tenspeed

I'm very tempted to pull my supercharger and take a peek if it's not much trouble. It's at 30K miles, driven easy and the best highway MPG's are around 24. I feel that it should do better than that.

DanfZX14

If you do follow through on this PLEASE take some photos while your in there and post them here. I am sure the group would be very interested to see what is going on inside that area!

trlman

From what I can see, the only issue with removing the supercharger, is the water cooled inter coolers. They reside in the supercharger housing, so a bit of coolant would have to be drained, replaced and system bled. As far as the reluctance for OEM to include a catch can, I believe most owners would not accept the responsibility of periodic draining.

DanfZX14

I guess I don't fit the definition of 'most' then....

But the car manufacturers could make periodic draining part of the regularly scheduled maintenance.

Swes

I agree it's simply the issue of draining the catch can periodically which people won't do. Cars have advanced baffling systems within the engine that forces the air to swirl and go around tight bends already anyways. Same as a catch can except the drain is back into the engine.The PCV system is not like the old days of a hole in the top of the valve cover straight to the intake manifold with a piece of fuel line.


Theres several contributing factors to the issues here part of it is driving style and user but also the manufacturers believed they could retain the PCV Systems of the port injected cars but there wasn't enough margin and thus we have the issues of valve coking we have now . I refuse to believe that valve coking is exclusively a new problem the result of GDI since diesels have been direct injected with PCV since the 80s and the new diesels don't have the issue nearly as often to make it a trend.


However, if I was buying a Q7 or another car with GDI , especially for a non mechanically inclined person, I would install a catch can simply for piece of mind.

GDI Tech

Diesels have dealt with it for ages as the temp
s the intake valves operate at are far cooler than a GDI (Gasoline direct injection) but the latest diesels have pretty intensive emissions systems that cause coking of the hot side turbines of the tubs and that has cropped up as an issue. Otherwise diesels have generally twice the oil capacity to deal with the added particulate contamination. Diesels also until a few years ago a "venting" PCV system. Pretty much any since the mandate of DEF particulate filter/clear systems have the more severe coking issues. Anyone that knows a large truck diesel tech, ask them to see there opinion. Trucking companies have been doing rebuilds, etc. on their fleets now far more often rather than add the new models due to issues.

As for OEM from the factory, we have talked in depth with several automakers and the barrier is both cost (even a .48 cent addition can is mixed due to strict budgets as the GM ignition switch debacle that caused GM billions) and the other is no new vehicle owner will accept another maintenance step as the target add's have been as little owner maintenance as possible for decades. The latest as Swes correctly points out have new designed valve covers and internal baffles to trap the oil mist internally keeping it in the crankcase, but that then also retains the damaging compounds and contaminates constantly entering as blow-by substantially increasing internal engine wear, thus the lowering of warranty periods on most GDI engine from 100k miles to 36k miles (BMW the latest to do so). So the trade off in reducing the coking rate is far shorter engine life, but as most buyers trade within 3 years, they seem to feel that is a trade off the new car buyer is willing to make.

tenspeed, please do remove and inspect and share pictures with us all!!! I did not have the time to do so on this Q7 and the more that are willing and able to remove their IM or SC and share what they find, the more accurate picture for the rest. One final note, we have had a system that self empties and does NOT contribute to emissions and has been shown to last 100k plus miles before needing and maintenance, but it is in the long patent process, and that is no guarantee the Auto Makers will even then implement as the consumers seem to be largely unaware of any of the issues so as long as that is the case, they certainly would not add to the cost to manufacture.

DanfZX14

It really is a sad state of affairs when the auto manufacturers will sacrifice quality and longevity over additional maintenance and corporate greed.