By on December 27, 2016


catch can

Mark writes:


I’ve had my 2015 Focus ST for 15 months and 14,000 trouble-free miles so far, and I’m really enjoying the car. The car is still 100 percent stock, but I’ll likely contact Torrie for a tune before long.

As much as I like the car, I’m really alarmed to read about the intake valve “gunk” issues with Ecoboost and other direct-injection engines. It seems as if DI engines have a real problem that the manufacturers really aren’t willing to acknowledge or address (if it even can be addressed).

What’s your opinion on oil separators and/or catch cans? Are they a good preventive measure, or should I just resign myself to funding a cleaning via walnut shells or other similar clean-up tactics when gas mileage starts to dip, power drops, or misfires develop?

Some of the more basic oil separators, such as one from Steeda, cost $65-80, while more elaborate catch cans run $200 or more, plus installation. At that higher price, spraying in a can of CRC’s Intake Valve Cleaner now and then and just paying for a cleaning at some point down the road might not be such a bad choice.

What would you say is the most cost-effective choice for someone like me, who plans to keep the car for probably 80,000–100,000 miles, but probably no longer than that?

Sajeev answers:

The ideal fix is a piggyback port fuel injection system. Toyota’s been at it for a while, with no internet chatter about walnut shell blasting. Since that ain’t happening on your motor (it’s going down on the soon-to-be released 4.8-liter V8), and because it’s turbocharged, consider installing a catch can as preventative maintenance.

Of course, that depends on the application. With a stock tune? Probably not. But after adding more-than-stock boost (via tune, bigger turbos, etc), consider it a mandatory upgrade. Catch cans are simple, cheap (but YGWYPF) and easy to remove/sell if returning to stock for resale purposes — which is highly recommended to claw back extra cash you won’t see otherwise!

What say you, Best and Brightest?

[Image: Shutterstock user Creations]

Send your queries to [email protected]com. Spare no details and ask for a speedy resolution if you’re in a hurry…but be realistic, and use your make/model specific forums instead of TTAC for more timely advice. 

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49 Comments on “Piston Slap: For a Cleaner EcoBoost, Install a Catch Can?...”

  • avatar

    a catch can won’t hurt, and is cheap enough to be a “why not” addition. AFAIK the Ecoboost engines haven’t had as much issue with build up as some others, especially not the horror shows inside some older VW/Audi DI engines. A catch can will help reduce one of the sources of build-up, but the other (oil seepage through the valve guides) will still be there.

    • 0 avatar

      Agree with JimZ, if properly designed, a catch-can will delay the need for media blasting or solvent bathing.

      They key here is “properly designed” which really comes down to correctly routed and not vented. As others have mentioned, you don’t want a vented can that could potentially give skewed MAP/MAF readings. You also do not want a can routed in such a way that it becomes pressurized under boost.

      I have seen some incredibly RETARDED setups in my time that have done more bad than good! It comes from lack of understanding how YOUR specific PCV system works or from people just playing engine bay dress-up.

      On my boosted car I use an in-line filter to keep crankcase fumes out of my charge pipes and intercooler. When the filter becomes grimey or clogged it is an inexpensive 2 minute replacement job. Much controversy surrounding the idea, which is why I could not recommend it, but it works for me on my car.

      I believe Mishimoto makes a nice kit for the Fiesta specifically? It has been a while since I’ve heard talks about it so I could be mistaken.

    • 0 avatar
      White Shadow

      That makes me wonder—what did VW/Audi do to correct the issue on some of their newer generation DI engines? I’m currently on my second A5 (2.0T) and I’ve had zero issues on my first one, even after putting 115,000 miles on it. The thing was still free of sludge and I never installed a catch can or anything intended to help keep sludge from forming. Nothing but oil changes using the correct spec synthetic oil every 5000 miles, which is admittedly a bit of overkill, but I’m of the “oil changes are cheap insurance” camp.

      Anyway, for whatever reason, the EA888 engine in my cars, despite being DI with no piggyback port injection system, certainly seems to be free of oil sludge issues. You never read about it in the Audi forums either, which is definitely not true with a lot of the earlier di engines.

      • 0 avatar
        Turbo Is Black Magic

        On the gen 3 they redesigned the PCV system, has a new big oil separator. Also the VW patent says to drive 15 minutes at an elevated RPM… can’t recall what RPM and it cleans them. The only bad buildup I have seen on a gen 3 was from someone that used cheap gas (89 or 87)..yes octane should not matter since no fuel his valves, but for some reason it made a big difference on build up.

  • avatar

    If the can is not properly sealed, it introduces an air leak in the manifold after the MAF sensor which will drive ECU nuts.

  • avatar
    Adam Tonge

    Jim is correct. A catch can will probably help some, but it won’t stop all oil/carbon build up. If it eventually does coke up, the Ford dealership, or an indy mechanic, can clean it up for a few hundred bucks (not $900-1200 like the VW/Audi dealership).

    • 0 avatar
      Big Al From 'Murica

      Can they? At last I heard Ford had no procedure to clean carbon deposits on the ecoboost motors and the only approved procedure was replacing the heads. In fairness it is a relatively small number of vehicles that seem to have had issues.

      I was told that the standard methods to remove the carbon resulted in potentially chunks of carbon migrating to your turbos and killing them.

      • 0 avatar
        Adam Tonge

        You can remove the intake manifold and clean it manually or walnut blast it. Ford may not recommend it, but it works and if done properly, won’t hurt the engine or turbos. They are more worried about solvent and snake oil quick fixes. Dumba$$es pouring seafoam in the brake booster and crankcase.

        The reason why the 3.5 ecoboost doesn’t have the same problems as some VWs is that Ford uses a process that sprays fuel on the valves on the exhaust stroke. As long as the engine is functioning properly, the valves shouldn’t coke up.

        • 0 avatar
          Big Al From 'Murica

          Is that the previous 3.5? The 2.7 has some sort of voodoo with the valve timing that got fuel on the valves I believe. And that was the real issue with DI I thought…carbon on the valves, not the intake.

          Anyway I have one and I don’t lose any sleep over it. I run good oil, change it frequently, and Italian tune up it from time to time. If it cokes up I’ll make sure I get a piggyback type system next time around.

  • avatar

    I went into DI/Turbo (New GTI) ownership with eyes open and budgeted for a “cleaning” at 40,000 miles. My goal for this car was low maintenance involvement as I didn’t want to have to putter around with stuff like this anymore. :(

    I have never heard of research that said it’s 100% effective. Some “say” it works but there are so much that goes into the buildup (# and length of trips, quality of gas, quality of oil, low vs Hi RPM driving) that I would rather just budget a cleaning than try to chase down a solution to a problem that I may not have.

  • avatar

    Manufacturers errors have now made owners responsible for maintenance that shouldn’t have ever been part of the plan.
    There is not one new car I’d own and if I did it wouldn’t be around after the warranty was up. An acquaintance used to keep his Jaguar right up until the warranty ran out and get another one even if the last one stayed in the shop more than it did in his driveway. Blind loyalty.

  • avatar
    Jack Denver

    If an oil catch can is needed, why aren’t they part of the factory equipment? Wouldn’t catching oil reduce emissions vs. burning it?

    • 0 avatar
      heavy handle

      Cars do come from the factory with oil separators which send the separated oil back to the pan. This catch-can thing is a hack.

      Nothing wrong with a hack if it’s designed to fix a specific issue, but I wouldn’t install one on speculation. Just because Audi got things wrong in a very specific way for a specific amount of time doesn’t mean that Ford did the same. They’ve probably messed-up in a completely different way: one for which a catch-can is completely useless.

  • avatar

    In my opinion it’s probably worth while. $200 is ridiculous for one though. They are pretty simple devices. Just make sure it gets emptied (I’ve seen people buy these for the bling factor and forget the actual purpose of the thing).

  • avatar

    Considered a catch can for my ’11 335d as many have experienced clogged intake manifolds. The tech who tends to the 335d says the huge number of highway miles for extended periods (IN NJ, IN FL, IN MT) help keep it cleaner than if used for mostly around town driving.

  • avatar

    Not that it helps in this case, but I envision a point where manufacturers install a service port in the intake manifold.

    Something like an a/c service port, I think. Once a year, you buy something that looks like a DIY a/c recharge kit, hook up the hose to the manifold service port, start the engine, and pull the trigger on the can full of intake valve cleaner.

    • 0 avatar

      Everyone is hoping for a miracle fluid that will dissolve CDs, but carbon can only be removed by physical means. You have to chisel it out, or blast it out with walnut shells, etc.

      The amount of money and effort that goes into various miracle-in-a-bottle treatments is astounding.

  • avatar

    $200 and not even cool looking

  • avatar

    Dual injection systems will become the norm. It’s just going to take a few class action lawsuits.

    The most cynical aspect of this DI gunk issue is that it really only comes into play once warranties are done. But manufacturers are starting to do the right thing.

    • 0 avatar

      >Dual injection systems will become the norm. It’s just going to take a few class action lawsuits

      Until then, I’m sticking with my port-injected vehicles.

  • avatar

    Just going to throw my two cents in here because I had that exact OCC for my Mazdaspeed3

    The car was full bolt-on running a custom e85 blend tune. The OCC was a necessity due to the amount of blow by produced by the strung out tune (At peak the K04 turbo was producing 24.5 PSI). Even if the science of the OCC produces no realized results the OCC still captured about 10 oz of fluid every oil change, to me thats better than circulating over and depositing on the valves.

  • avatar

    Motor oil has no business in your intake, install the can – they work.

    For those who say that manufacturers would surely have included them if they did anything useful – you have way too much faith in your corporate overlords. Catch cans are our of sight and won’t reduce the cost of in warranty repairs, so they’re cut to save on production costs. Plus the owner needs to remember to empty the can occasionally which presents a whole slew of problems all by itself.

    GM LS motors are notorious for oil in the intake. My can collected about 125 mL per 15k miles, before the supercharger ;)

    • 0 avatar

      The new LT engines also had oil in the intake but GM reduced the amount of oil in the dry sump engines to supposedly address that. I, too, am concrned that my LT1 could have this issue and researched the catch can. I have no problem with a couple of hundred bucks to keep the valves clean and was ready to pull the trigger until I read a thread on Corvette Forum where a guy who had engine issues had his warranty claim denied due to the catch can. Not going to chance losing a 100K drivetrain warranty on a high performace car, so I will just have to see if it becomes a problem. At least removing the intake on LT engines is pretty much a cake walk.

      RE: Factory catch cans. The new Camaro comes with a factory catch can that self drains. Not sure if it is on all V8 models or just the killer ZL-1

  • avatar

    Can anyone cite any definitive/authoritative sources that analyze credible data that demonstrate that properly installed catch cans on direct injection gasoline motors actually significantly reduces carbon build-up or produces other significant benefits?

    • 0 avatar
      Big Al From 'Murica

      I read it on the internets.

    • 0 avatar
      Adam Tonge

      Good luck finding info either way. I don’t know if the 2.0T washes the valves with fuel like the 3.5TT. If it does, the catch can mattters even less. There just isn’t enough info out there either way. If he stomps on the gas and gets into the boost every so that may be even more benificial.

      Also the 2 part BG Direct Injection cleaner works, but I don’t think manufacturers want you using it.

    • 0 avatar

      This is discussed to death on the GM forums for the HFV6 found in Camaros, Caddies and others. Some folks swear it is keeping the engine clean, others say it does nothing. I would think there are just so many of those engines out there that someone would have actual info. My car had a tiny bit of oil residue in the intake boot-I’m not concerned about this.

  • avatar

    I had an intake valve service done earlier this spring on our 2.0T FSI Passat at 125k miles, after seeing some random misfires in cold weather. Usually the carbon buildup telltale is misfire at first start, but our car wasn’t necessarily doing that. But it was about 9 years old at the time, and a good time to take a look.

    Shop charged about $350 to remove the intake and clean the intake valves using a variety of BG chemical treatments + manual scraping to remove any gunk. The mechanic said our car was about a 3 on scale of 1 to 10, and to keep “doing whatever you are doing.”

    We have a new gen 2.0T TSI in our 2017 GTI now, and I’ll be interested to see if this continues to be a non-issue.

  • avatar

    Apparently another option is to simply run a different engine oil. If you ever poke your head into the black hole of lubrication information that is, try looking for people with DI motors who consistently used Redline or RLI’s renewable oils for intake port cabon issues. Apparently with those two oils, people don’t have the carbon issue due to the properties of the basestock of each oil (Redline is an ester basestock, no cheaper PAOs, RLI uses a bio and synthetic basestock–unsure of composition beyond that).

  • avatar

    I have a 2015 focus st. Stock. About to roll over 20k miles.

    It suffers from random misfires on cold starts.

    Ford has had the car for 58 days over the past year and a half. They’ve replaced all the plugs and all the injectors, collected flight recorder data for Ford engineers, and just this past october- the cylinder head was replaced. Though they wouldn’t say why, the common thought is that they were replacing the head due to carbon issues.

    Long long long story short, 2 months after the cylinder head replacement, the cold start misfires were back (worse than ever actually) and setting off my check engine light yet again.

    I thought about trying acatch can, but forget that. The way Ford treats modified cars when it comes to warranty work is enough to scare me away from messing with the car. They spent days trying to determine if I modified my car in any way… And other dealerships I contacted also started our conversations by asking if my car was modified.

    • 0 avatar

      Intercooler condensation?

      But- hate to say it- at this point why haven’t you filed for a buyback?

    • 0 avatar

      2015 Ford Focus ST with cylinder replacement and many other issues with 20,000 miles on it?


      Ford quality control is EXCEPTIONAL, Ford dealership service departments and Ford HQ are more consumer friendly than Lexus, and the Focus ST is one of the best, most reliable performance bargains in the history of motordom according to many part time TTAC staff writers.

      • 0 avatar

        Fun car, poorly built and EXCEPTIONALLY bad service from Ford dealerships.

        Like, monumentally bad service experiences from multiple dealerships. The old fashioned jerkoffs that run Ford service departments are truly a sight to behold in 2016.

        Going to a Ford dealership feels like nothing has changed there for decades. It’s not good.

        • 0 avatar

          I like the European feel/handling/ride/steering of the Focus, but it’s let down by iffy fit/finish, some poor quality interior materials, poor reliability, the automatic transmission (c’mon Ford, there’s no excusing that), etc.

  • avatar

    Porsche has had issues with the SAI (Secondary Air Injectors) on the ’96-’98 993 models with OBDII. The ’95 can have the problem but there is no “Check Engine Light” since it’s OBDI. LOL.
    DI engines on later models have had issues as well.

    @sajeev-mehta; I like the Mercury Marauder idea. Cool cars, bullet proof chassis and engine. Police still use the Crown Vic format.

  • avatar

    Any comments on using a catch can in cold weather regions?

    I thought about getting one for my DI engine but it seems they can freeze from moisture and effectively block the PCV function.

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