Subaru Ascent Forum banner
1 - 10 of 10 Posts

·
Registered
Joined
·
180 Posts
Discussion Starter · #1 ·
Is anyone considering water/meth injection to keep intake valve carbon built up away? Do we just wait for it to build up then do walnut blasting?


I was pondering a setup with the smallest nozzle offered, no tune should be required with this small amount of water/meth injection. My biggest concern would be warranty. A decent setup costs about $400 and is relatively easy to install.
 

·
Registered
Joined
·
1,406 Posts
ideally intake suppose to be clean and only exposed to air (mostly oxygen and nitrogen; no carbon). The issue is the crankcase vapor/gas returning back into the intake pathway - that's what you should address first prior to adding a system onto something that's already complicated.

Look into oil/air separator like the STi guys already doing before creating a potential issues.

As for warranty, that's a whole other topic
 

·
Registered
Joined
·
932 Posts
We've had a few threads about this - I'll try to find them, possibly merge them if I can locate them - after personally talking to Subaru about the issue, they said they're aware of the issues with carbon buildup and have made some engineering changes to the engine cycle along with other things to prevent it from happening.

From what I've heard on some other forums, too, the Idemitsu branded oil that Subaru uses for its OEM stuff is exceptional when it comes to NOACK/evaporative qualities, which means less unburned oil ending up on your intakes.

The biggest thing you can do is make sure you're filling up with Top Tier fuel, not a bargain vendor. If the fuel burns more completely, you'll have less particles recirculating.

That being said, I don't think I personally would go to such a great length to do a WMI on this engine. Worst case scenario, if it's anything like the BMW/Audi/VW's that have had issues, primarily with the way the turbo EGR dynamics worked, you're looking at a media-shell type blasting (walnut shell blasting) every hundred thousand miles or so.

If they (Subaru) offered an OEM type of Oil/Gas separator, I would do it. But, they don't. And their engineers are not ignorant of the problem.

If I *DID* have a problem, Subaru seems to be the type of company that just might cover a cleaning under some type of extended warranty in the future.
 

·
Registered
Joined
·
20 Posts
I was concerned about this when I first bought by '14 FXT but I'm at 62k miles now and haven't had any issues yet (completely stock). I use Pennzoil PUP 5-30 oil and BP 93 gas. I'm not real concerned with the Ascent. They have probably have worked out a few kinks since the FA20.
 

·
Registered
Joined
·
357 Posts
oil air separators are where its at to save one the motors, but this is more talking about the EJ with all its problems this FA is going to be something completely different.

The oil air are great they are expensive but IMO worth is on the EJ, I doubt that I would think about is on the ascent as for meth injection been down that road before in a 03 WRX its not worth it to me unless your looking to use it for something other than to avoid carbon build up.
 

·
Registered
Joined
·
583 Posts
We've had a few threads about this - I'll try to find them, possibly merge them if I can locate them - after personally talking to Subaru about the issue, they said they're aware of the issues with carbon buildup and have made some engineering changes to the engine cycle along with other things to prevent it from happening...

I think Robert Mauro(?) posted a nice article about that..
Merging threads is probably a good idea.....
Maybe some sort of notice is needed for people to search existing threads (even feebly) before posting a new thread.....:nerd:
 

·
Registered
Joined
·
561 Posts
Besides the specific oil they call for what did Subaru do on these new FA25 engines to prevent carbon buildup?
I know Toyota runs dual injectors, one in the combustion camber and one in the plenum that sprays directly on the valves every so often to clean them off. Subaru have something similar?
 

·
Registered
Joined
·
1,136 Posts
I would not be too worried about carbon buildup, but if you need to do something, Subaru has a fuel injector cleaner you can purchase. My son's use it on their WRX's. You put it in the pcv hose line. I have enclosed a video link.

https://estore.subarupartswarehouse...r-Cleaner-16-oz-Can/49506088/SOA868V9150.html



You can also use EPR from BG as a cleaner after 10,000 miles. You put this in your oil just BEFORE you change the oil and run it for 10 minutes, then change the oil.

https://www.bgprod.com/catalog/engine/bg-epr-engine-performance-restoration/

Both great products, if you feel the need to do something other than use high quality fuel.
 

·
Registered
Joined
·
932 Posts
Yeah, the upper engine cleaner is cheap enough I'd be willing to do it as part of the 15k service... It requires the special tool, so don't forget that.
 
1 - 10 of 10 Posts
Top