[kiannasmiles7]

Vehicle Details:

Forester Sport

I took my 2019 Forester Sport to the delearship becaue check engine light came on and of course disabled practically everything. They said the pump was bad and this is a known issue so Subaru extended the warranty for this. While in there, the dealershipcalled and stated the intake valves are caked with carbon and this can cause intermittent starts and stops etc. They also, mentioned they can clean it while in there for a mere $575- this is a lot seeing as I was expecting warranty work at no charge. But they said if my check engine light would come on and they found this to be the problem on its own, it would cost about $1150 to do the same thing as it is labor intensive. They stated this is normal with direct inject engines and the carbon is going to build up. They are going to take before and after pictures for me. I told him I push the A to turn off the auto start stop at lights etc. as I have never been a fan of that feature and do not know how it saves gas. It seems like it would use more. But anyway, does this sound normal?
Additionally, is there any other way to clean these valves or keep them maintained so they do not get gunked up? I mentioned fuel injector cleaner- you know that Lucas stuff – Tune up in a bottle. He said that does not get through the engine where these valves are and there is nothing that can do this. He recommended just a fuel injection cleaning every 30k miles by them to minimize the caking but he said it will need to be cleaned again. Sounds terrible and like a scam to cover these defective parts they know about and want to offset the cost by having people save $700 since they are “already in there fixing the warranty problem.” Am I getting scammed? And do I never see any service coupons on my dealerships website. Where can I find coupons? I used to work for a Toyota dealership and you couldget coupons off the site and customers were mailed coupons. Thanks for any tips, advice and feedback.

 

[adc]

If they do a mechanical cleaning of the valves or a walnut blasting its not a rip-off (IMO)

 

[j3rf]

Yes, carbon build up on the backside of intake valves with direct injection engines is normal. Yes this should be cleaned off periodically as a maintenance item. The service is not inexpensive. Subaru has a chemical process to clean the intake valves, but a walnut shell blasting is the better way in my opinion.

The reason why they are recommending the intake valve cleaning with the thermo-control valve replacement is because the intake manifold and one time use fuel pipe has to come off for both jobs. Subaru is paying for the new intake manifold gaskets, fuel pipe, and labor to remove and re-install the manifold so you're just paying for the intake valve cleaning service itself. Subaru is not going to pay for the intake valve cleaning until it starts causing a rough idle or misfire DTCs, which may be far later down the line when most warranties are expired.

 

[TTiimm]

Coupons are available on the MySubaru app or website.

Warranty aside, $575 for mechanical cleaning is a good price. I paid $900.

Below are photos of my 2015 before and after intake valve cleaning.

It had drivability issues - hesitations and felt like it was misfiring. Three applications of chemical cleaners didn't fix the issue. Mechanical intake valve cleaning fixed it and it runs so much better now.

It isn't a scam. It's the nature of these engines. Chemicals won't cut it. An air-oil seperator will help but even that will only slow the process.

Before...

After...

 

[auntiesuebee]

Carbon buildup is normal. Tune-up in a bottle is not the answer once the buildup occurs.

 

[Cddelta]

I would want to see before pictures. Intermittent start stop problems are usually related to 12V batteries in poor condition. If you haven’t replaced your 12V battery in the last two years, I would start there. Subaru uses a larger sized battery now, a Grpup 24F.

I have 130k miles on my engine, and it’s performing well. I would be surprised if you have carbon build up unless you’re using garbage fuel.

 

[TTiimm]

I would be surprised if you have carbon build up unless you’re using garbage fuel.

The 2019 Forester 2.5 liter engine is direct injected - fuel is injected directly into the combustion chamber and doesn't touch any part of the intake, including back of the intake valves.

In such an engine, carbon buildup on the back of the intake valves has nothing to do with fuel.

 

[Cddelta]

@TTiimm yes, poor oil and a stuck PCV valve will also cause buildup. I would expect rough operation and hesitation, but not intermittent start/stop functions. I’d expect for $500, the dealer is going to perform Subaru’s Top Engine Cleaner induction service, which is a literal $10 can they spray into the induction hose.

 

[TTiimm]

@Cddelta

Buildup is endemic to direct injected engines.

Poor oil, stuck PCV valve and a whole host of other issue can certainly exacerbate it. None of these apply to my car but it had lots of buildup. See the before photo in post #4.

That photo was taken subsequent to three applications of Subaru's top engine cleaner performed over a 5000 mile period. It didn't even put a dent in it.

If you have a direct injected engine then you have valve deposits. The only question is whether it is bad enough to cause driveablity issues. If it gets that bad then mechanical cleaning is required. Again, reference the before and after photos in post #4. This isn't something I made up.

$250 is what I paid for each application of the Top cleaner. $550 is about in line for a walnut blast. Most independent shops charge $600-ish.

The OP isn't being ripped off.

The PDF linked below is Subaru's process.

 

[auntiesuebee]

<snip>
The PDF linked below is Subaru's process.

It depends on the dealer.

At the dealership where my son works, they do not use the top engine cleaner or walnut blasting. They found with any sort of buildup the top engine cleaner is pretty worthless.

They have a special tool that essentially scrubs the back of the valves. As I recall the price is around $750, but price is going to depend on the dealer's labor rate.

 

[TTiimm]

@auntiesuebee

I'd be surprised to find out that the tool isn't an Autotool HTS558 walnut blasting machine. If it isn't then I'd like to know what it is. Maybe you could ask your son if you remember?

I'd love it if my dealer offered this type of service. The only shop I trust to do this is a very expensive local performance shop. $750 at the dealership would be welcome.

 

[Fibber2]

There is actually a feature built into the 2019+ GDI engine that is designed, at least in part, to help reduce the build-up of valve carbon, but unfortunately @kiannasmiles7 decided to turn it off. That's a shame.

It's well documented that one of the downsides of GDI is carbon buildup in the intake above the valve seat. These engines run well at speed, but idling has been identified as the enemy. Poor breathing dynamics at low flow causes backswirl and the deposition of fuel up onto the lower intake, valve top and stem. AS/S reduces needless idle time, reducing the incidence of carbon build-up.

Yes, AS/S does save a tiny amount of fuel. But it's minuscule. On average I log about 12 ounces per tankful, or around 3 miles extra per fillup. Hardly enough to move the meter on the EPA test. But it makes a huge difference in terms of minutes of idle time per tankful. I often see as much as 20 minutes of idle elimination per tankful, prime-time carbon buildup damage not taking place. To me, that's a great reason to have and to use AS/S....

 

[j3rf]

@auntiesuebee

I'd be surprised to find out that the tool isn't an Autotool HTS558 walnut blasting machine. If it isn't then I'd like to know what it is. Maybe you could ask your son if you remember?

I'd love it if my dealer offered this type of service. The only shop I trust to do this is a very expensive local performance shop. $750 at the dealership would be welcome.

My alternate tool is zipties that go in my drill chuck. 😂 Helps break up the big sticky chunks into something easier for the walnut shells to devour.

 

[TTiimm]

@j3rf

Do they need to be Subaru OE zip ties or can aftermarket zip ties be used?

Do the JDM STI zip ties perform better? Any compatibility issues?

 

[Fibber2]

@TTiimm As long as they are metric zip ties, it's good enough. I wouldn't use SAE or Imperial dimensional whips on a JIS engine. And certainly NEVER whitworth. I only give those house space because I gravitate to old British stuff. Generally incompatible.

 

[TTiimm]

I wonder what the OP would say if he knew that he might pay $550 to have his valves cleaned with zip ties.

 

[Wangle]

I think some are somewhat missing the point. The quote is cheaper because they are already in there, with the intake already being removed. I don’t think any symptoms are occurring from the dirty valves. I may have missed it, but I don’t see the current mileage. The quote is a very good bargain IF it is a walnut blasting or equivalent (I don’t know what the equivalent would be.), and high praise to the dealership for offering this to you while your intake is off! I would look at the picture of the valves while noting the current mileage, and I would almost certainly get this done.

 

[PeterfromOz]

Carbon buildup is normal. Tune-up in a bottle is not the answer once the buildup occurs.

Agree. If you have direct injection nothing in the fuel is going to get to the top of the valves. You might end up with only shiny piston tops.

 

[cayankee]

Volkswagen and a few other vehicle manufacturers had this very same problem. They ended up incorporating auxiliary injector(s) in the intake manifold to stem the carbon build-up issue with their engines in later generations. Those added injector(s) are only active part of the time and the ECU automatically keeps the A/F ratio at the proper levels.
Has Subaru incorporated this modified direct injection system into the later years vehicles?

 

[TTiimm]

Has Subaru incorporated this modified direct injection system into the later years vehicles?

The FA20D and FA24D from the BRZ have Toyota's D-4S dual injection system.