dhrdrm

I recently bought a 2014 is250 f sport with 75,000. I changed spark plug for it. To do that, I remove the air intake manifold, and found out carbon built up on the intake valve. Does anybody have experience on this issue?

Because I heard is 3rd is different with previous generation, and the carbon problem is been solved. But I saw much gunk on the valve. Another thing is, every time cold start the car, the RPM start at 1200, first go down, then go up, finally stable at 800. Further more, 2 mpg is less then original. I heard crc or sea foam would help. I just own this car, so please give me some suggestion. Thanks!

Sasnuke

Welcome to the forum and congrats on your new ride!

The carbon build up issue was corrected for 3IS, but like all direct injection only engines, there will always be some carbon buildup.
Reality is in all engines there will be some carbon buildup.

You can certainly use some Sea foam to help eliminate the carbon that is there already.
For the idle issue, I would try simply cleaning the throttle body and see how that goes first.
Make sure you are using the correct octane of fuel since the car is new to you, you don't know what the previous owner was putting in it.
You can also add some fuel injector cleaner to the tank to help clean the injectors...which could improve you idle issue as well.

Also, if you can install an Oil Catch Can, that will help reduce any further carbon buildup.

dhrdrm

Really appropriate your reply! When I removed the intake manifold, there’s a fuel line connect to it in the passenger side. Is that for cleaning? I am using Techron for fuel additive. Is this one okay? I would definitely try to sea foam my IS.

About oil catch can, there are so many different types, do you have any recommendations?

Sasnuke

1. there’s a fuel line connect to it in the passenger side. Is that for cleaning? Since the 250 is direct injection, I wouldn't open any fuel lines under the hood unless you're absolutely sure the fuel pressure has been bled off. The pressure from the tank to high pressure pump is about 50PSI and after the high pressure pump, anywhere up to 1800PSI (it won't normally be that high, but it could). I would stick with the fuel injector cleaner that you add to the gas tank.

2. I am using Techron for fuel additive. Is this one okay? I haven't used Techron personally, but it seems to be a well rated product, so I think you are good sticking with the Techron.

3. About oil catch can, there are so many different types, do you have any recommendations? I've been slowly looking into getting one myself. There are so many out there...good and bad.
Cost is also a considering as you can spend anywhere from $100 to $500...and the more expensive product is not necessarily better.
Some key features you want to look for: external indicator of level inside OCC (so you know when it needs emptying), drain hole (for ease of emptying), internal filter (usually bronze), some type of baffling system to separate the oil from the crankcase vapor.
You want one big enough to hold enough oil between oil changes, but not too big that you can't find a spot in the engine bay to mount it. Anything bigger than half a litre is likely too big.

Here is a link to one example: https://www.mishimoto.com/compact-ba...an-2-port.html

E46CT

Solvent for the fuel would just be added to the gas tank.

Solvent for the air/fuel mixture would be added to a vacuum line somewhere. But very little and very slowly--you can risk hydrolocking the engnie they say if you go too fast or too much.

Something like adding solvent is more for maintenance and less for repairing. Once it's built up enough, nothing short of pulling the heads and manually cleaning all the valves and valve seats will really help.

Go ahead and run your techron and seafoam and drive it hot and extremely hard. your best chance at slowly eating away at the carbon.

dhrdrm

Thanks your professional response!