No surprise my wife's 08 IS250 has carbon buildup. It has had a catch can on it from day one I learned about these cars and the carbon issue. So I custom mounted an Elite Engineering can.

She was getting some weird idle and running rough so I decided to do a spark plug change (at 160K mi ASSUMING a plug change has been done already in the cars life but I have no way of telling) and to also remove the lower manifold to see the valves. I was able to crudely hip off larger chunks of carbon and vacuum them out and use some brake cleaner initially. The plugs were horribly fowled and I'm surprised the car ran as well as it did. Some new Autolite plugs went back in. I have a feeling the OEM calls for a Denso plug with THREE ground straps so the cars will stay running longer due to sever carbon buildup issue

Buttoned the car up after the plug change and all was well. So a week later I decided to look into walnut blasting (which I could do) but then I came across CRC Intake Valve cleaner specifically for DI motors. So I gave that a try since it would be a lot less hassle.

Got motor to operating temp, ran motor at 2K rpm and put the can through the capped off vacuum port at the top back side of the motor (not the PCV port on the back) per can instructions. Let it sit for 1 hour to soak. This is where it gets fun...After letting it sit for a good 45-50 min (my wife had to go out so I jumped the gun) I started it and billowing white smoke started coming out. Fine, I'm not surprised since a lot of gunk is probably getting burned off. Didn't smell like burning oil or anything catastrophic so I let it idle. I then blipped the throttle maybe to 2K and a noticeable CLACK CLACK happens. My initial thought was I hydro locked the motor bringing the rpms up or something on that first rev.

At this point I about ***** my pants thinking a valve got screwed up, but it wasn't doing it at idle...only slightly elevated RPM which I thought was odd. So I SLOWLY took the car around the block...sever stumbling and misfires along with white smoke still...I kept creeping around the neighborhood, bringing up the speed and rpms, the CLACK CLACK would come and go so I would let off and coast.

So I did a couple of laps around the neighborhood thinking if I just screwed up the motor and my wife is 10min from needing the car to go to a work function...ugh. I kept putting around, the car would wake up and act normal, the CLACK noise went away at all rpm's and then I get CEL (checked and came back as multiple misfires....no big deal I figured it would). Cleared codes and kept driving. Finally the car is acting 100% normal. No issues days later and the car is fine. The can says to let it sit for 1 hr then get on the highway for at least 10min. After what I went thought I don't know if I'd want to go jump right on the highway...

SO, for anyone doing the CRC treatment you may want to give yourself and the car some time to work itself out. Expect smoke billowing out the tips (LEAVE WINDOWS UP!!!) You may get CEL that needs cleared. At some point I plan to take the upper intake off and look at the valves again to see if it helped at all. But to be honest, I may feel better doing the walnut blasting and vacuum debris out than to spray a whole can of liquid-like cleaner through the intake. So as of now I can't give any feedback on how well the valves got cleaned or not.

 

The odd noises might have been portions of the carbon breaking off and jamming within the valve seat temporarily. But glad the noise went away and the car seems to be running better.

To this day, I've never done any of the Seafoam or other liquid engine treatments; they scare the bejesus out of me!

 

The valves were not terribly gummed up and if they were I was able to remove the large chunks, but that's possible.

Eager to tear into it again and see if there is any improvement though.

 

So the instructions say spray entire can into intake with it at idle or off?

I will assume one does this at idle because if done with the engine OFF, some of the intake and exhaust valves are bound to be open. That said, in the off condition, this could easily fill a single cylinder enough to damage it when started.

Did it say anything in there about doing an oil change afterwards to get all the crap out of the oil system? If Not I would highly recommend doing so as it will be nasty and could lead to extra wear and tear!!!

 

You let the get to operating temp then spray the can in spurts with motor at 2000rpm, let idle for 1 min then let is sit for 1 hour. Then they say to get on the highway and drive normal for 10min. After seeing how the car acted for me, getting on the highway would have been dangerous given how much misfiring and sputtering the car was doing to get up to highway speeds.

No mention of changing oil after this is done, but the car is due soon so I'm letting it continue to clean then change the oil.

 

Any product that has enough solvent action to remove carbon also breaks down the oil. That same product was used in combustion and likely cleaned / disturbed deposits in the head, piston, and rings which means it very likely went past the rings right into the crankcase.

The solvent likely flashes off once the engine came to temperature, it's the broken down carbon that is nearly is hard as sand that concerns me.

Adding to the above; nearly all other top end cleaners tell you to perform this process when your oil change is due or perform the OC after doing the process. Its because of the abrasiveness of the carbon deposits circulating in the oil.

 

I have 182 thou KM on mine and I am not sure how this problem manifests itself. The car seems to run fine and I guess it's a little rough when it first stars and idles at around 1800 rpm and gradually moves down to 800 to 900 after warm up. (It's cold here right now in Ontario) What am I looking for? Smoke, sputtering, stalling ? Thank you.

 

Its a slow progression but can be everything you stated and includes stumbles, misfires, sluggish acceleration, stalling, and in worst cases hard to start.

I'm guessing its more common to soccer mom car doing countless short trips, never reaching full temperature, seldom seeing WOT which when warm creates high port velocity and turbulence that helps reduce build up.

What people fail to see is short trips is severe duty and wears an engine more. Mine that gets started, driven 30 miles and turned off. Along the ways it hits full temp and sees WOT...

 

Take it from me. I used 3 cans back to back 1 of CRC, and 2 of seafoam. With 15 minutes in between cans. The valves where clean!. My route was for the seafoam put it in an industrial squirt bottle. Ran a hose from the port above the purge valve. Electrical tape around the port if hose is over sized. Hold RPMS at 2k. About 2-3 second bursts if possible. The car will misfire a bit shut it down for awhile. Start it back up it may misfire again slightly let it idle then shut down and restart. The misfires should be gone. Drive it like you stole it in a safe manner. Change oil, and repeat in about 50k miles. Carbon is not going away.

DIY at your own risk!

 

Hi, is the capped off vacuum port you referred to in your post, the one shown in the attached picture? Thank you!


Capped-off vac. port

 

I did mine at the intake and not at the vac port. Did it at 130,000 km or so.

I didn't get any white smoke whatsoever, but I got a puddle of brown oil at the bottom of the car. The engine was running so smooth afterwards.

Maybe doing it through the vac port would be better?

 

That does not answer my question though.
Where the brown oil came from? Was that he oil drained from the car so you changed the oil?

 

Sorry, I wasn't trying to answer your question. I was just telling everyone my experience in using CRC. The brown oil probably came from the gunk that was cleaned off from the throttle body.

I did some research on where this vacuum tube could be and found that it is the PVC tube going back to the engine, but they say that doing it this way doesn't evenly distribute the product onto the intake valves.

 

Yes I used the same one.

 

This whole article is getting me a little worried. Started noticing my IS have a rough idle, but none of the other symptoms. 105,000 miles (170,000 KM) on the odo. What would you recommend checking to determine if the engine has a buildup issue?