Turbocharged, direct injection engines and catch cans

I recently purchased a Focus ST and have been looking at a banner specific forum.  The dogma on that site seems to be that if one does not install a catch can in the PCV system of the FoST, carbon will build up on the back side of the intake valves and cause issue at higher mileage levels.  The signal to noise ratio on that site is still in question so I though I would check here to see if there is any validity to this line of thought.  This is my first first forced induction/ direct injection vehicle so pardon my ignorance.

It helps. It's a pretty common modification for the Mazdaspeed3 as well as a few others with DI motors but lacking a port injection system seen on newer DI cars.

Blocking off the EGR is where you will get the biggest reduction but that's modifying an emissions control.

You can also add either port injection or meth injection to the car which will reduce the buildup on the valves as well. Both are pretty well developed for the MRZ and it's derivatives.

Nothing to add except that they say the same thing about my 3.5L Ecoboost F-150.  So far I have not installed a catch-can. I am also interested in what the fine folk on this forum think on the topic.

I dunno.. Seems a bit Bro-Sciencey...   

https://rationalwiki.org/wiki/Broscience

In reply to The0retical :

there isn't EGR on the ST motor.  

And, field wise, I've not heard of a rash of deposits that other OEM's have with their DI systems.  So Entropyman- it's more about if you want to spend the money or not.

Wait, so does the catchcan not help? Or is it that there aren't the problems with deposits we've been told?

I don't read any forums but this one, and I am under the impression that a catchcan is almost necessary for a Speed3, if not the FoST.

In reply to alfadriver :

Listen to this dude. 

There are a lot of these engines out there in cars, trucks, and suvs  that have high mileage, and no issues. This isn’t a common issue that I’ve seen on Ecoboost engines. Ford doesn’t put one on these engines, so their testing must’ve said it wasn’t necessary.

i don’t know that I’d believe the people trying to sell me parts over the people that designed, tested, and manufactured the engine.

CyberEric said:

Wait, so does the catchcan not help? Or is it that there aren't the problems with deposits we've been told?

I don't read any forums but this one, and I am under the impression that a catchcan is almost necessary for a Speed3, if not the FoST.

There is a severe lack of science around wether they "help or not"...  Mostly bro's talking about what might happen or look at all that "oil" i'm sure its bad for the engine...

Same people also "require" premixing RX7 gas with some super special japanese oil..  

alfadriver said:

In reply to The0retical :

there isn't EGR on the ST motor.  

And, field wise, I've not heard of a rash of deposits that other OEM's have with their DI systems.  So Entropyman- it's more about if you want to spend the money or not.

No joke it's a 30k mile maintenance item on a lot of BMW engines.

The theory makes sense, it can't hurt, but you'd have to do a lot of testing to be sure it would help. From what I understand most back-of-the-valve deposits are caused by combustion byproducts rather than oil vapors from the PCV system.

In reply to alfadriver :

I defer to you. I went and made the assumption based on the MZR/Ecoboost relationship but it appears they're only related by block design. So that's what I get.

In reply to z31maniac :

I'd heard that from several BMW owners. I don't have direct experience with it but I know it's a big issue with the MS3 right around 30k miles.

The0retical said:

In reply to alfadriver :

I defer to you. I went and made the assumption based on the MZR/Ecoboost relationship but it appears they're only related by block design. So that's what I get.

In reply to z31maniac :

I'd heard that from several BMW owners. I don't have direct experience with it but I know it's a big issue with the MS3 right around 30k miles.

When Ford's DI went into production, you can use that as the time that the two engines stopped being the same.  Which is in the 2011-13 range.  And (oddly enough) none of the turbo DI design from Mazda ever went into the Ford engines.

I've noticed that this mod is very popular with just about every modern vehicle I've had experience with.

Personally I think that with modern stuff being so capable and complex (not as easy to do legit mods) people are so desperate to get in there and fiddle with stuff, this is something easy they can do and not actually do any harm.

My view is  this : Auto makers spend MILLIONS of dollars on creating engines , and R&D. do you think some 100$ peice of aluminum can will make all the difference in the world? doubtful. coming from the world of VW, it has been proven time and time again on VW TFSI engines (DI) that they do nothing at all, as for ford, YMMV

Saron81 said:

 Ford doesn’t put one on these engines, so their testing must’ve said it wasn’t necessary.

In general, I agree with this sentiment. However, you also have to keep in mind their requirements. They are trying avoid warranty claims while reducing costs as much as possible. They also want keep maintenance costs and work as low as possible. Catch cans have to be emptied periodically. Joe Average with an Ecoboost-powered Escape isn't going to want to do that every 10k miles or whatever, and if it means they have to take it to the dealer to get it done, that's more cost for him.

So, the engines will run for 150k without one, that's great, but it doesn't mean they will be as clean or run as well as they would WITH one. I have one on the SHO. I don't know if it helps. I figure it can't hurt, and it wasn't that much money. This is what I drained out of it last fall after about 8k miles of driving:

It's mostly water.

Counterpoint: installing a catch can would require the owner to drain it every couple thousand miles or less, depending on usage. When a certain portion of the population can't even be relied on to get their oil changed, adding this type of requirement to a mass production car seems unlikely even if there were benefits to be had.

That said, I have no opinion as to whether or not they matter on the FoST. I don't have one installed. I *do* have a catch can on my RX-7 and I also premix and have solid justifiable reasons for both.

edit: lol, Tom beat me to the submit.

MINI and VW/Audi have a lot of carbon issues.  They'll start having driveability issues around 70K. We do quite a few walnut blasting jobs on them.

I haven't seen any issues with the BMW DI motors so far.

Quality of fuel and oil maintenance can make a big difference.  The more oil that is burned the more deposits, so I don't recommend the 10-15K oil service intervals the Germans like to push.

A can of seafoam every 20K through the intake will help avoid major carbon buildup too.

tjbell said:

My view is  this : Auto makers spend MILLIONS of dollars on creating engines , and R&D. do you think some 100$ peice of aluminum can will make all the difference in the world? doubtful. coming from the world of VW, it has been proven time and time again on VW TFSI engines (DI) that they do nothing at all, as for ford, YMMV

I put one on my 2013 Mustang GT, it would catch a noticeable amount of oil in 3k miles. 

I have a catchcan on my TDI and my neon, both get emptied every oil change. The TDI is much happier with the catch can. 

Happier in what way?

In reply to Toebra :

I was thinking the same thing..  Define happier?

Great input, thanks everyone.  Sounds like it's not going to be a priority for me.

I installed one on my wife's FoST last month.

Our issues started around 65K miles(November). Lack of power, and intermittent bucking with misfire codes. She was stationed in VA, and I drove out to diagnose and attempt to repair away from home; a set of plugs cured it. At 75K it began having a cold start rough idle along with a CEL again. At least it waited till she got home to throw a real fit

I found oily residue in the intake manifold and some pretty ugly buildup on the backside of the valves.

To my knowledge thus far, Ford has not admitted that this is their problem and my car is out of warranty coverage anyhow. Plenty of research online says this is common occurrence with DI motors since there is no fuel on the backside of the valves to cool them and keep them clean. Much ado about chemical cleaning and the possibility of washing all the junk thru the combustion chamber and turbine. Ford says no walnut shells. What's a guy to do?

Symptoms cleared up and CEL shut itself off after I cleaned out the intake manifold and what I could remove from the valves. No idea if the catch can will help, but I figure it can't hurt anything.

Catch cans aren't enough to 100% eliminate DI buildup, but less oily residue being fed into the intake is certainly not going to hurt and should be a good thing for pretty much any engine.