Hi All,

I just thought I would share with you some of our experience with KCLV and some ideas of how to improve it. For those of you who haven't heard of it, KCLV stands for "Knock Correction Learn Value." For those coming from the Subaru tuning world, its sort of akin to the "Advance Multiplier." It is simply a long term ignition correction factor. After you flash your car or reset your ECU, the KCLV goes to 15. Once you start driving the car, particularly doing long pulls at high load, the ECU starts bumping the KCLV up in small incremental steps until some knock is detected.

We have tuned quite a number of ISF's, and generally find them to be very consistent in their response to tuning, but occasionally, there are what I call "KCLV challenged" cars that tend to run lower KCLV with the tune, and without the tune, even those running 93 octane.

So recently, we purchased a 24,000 mile 2014 IS350 F-sport for the purpose of developing a Supercharger Kit, and upon initial tuning, we discovered that this was one of those "KCLV challanged" cars. Even on stock tune, KCLV was at about 15-17, whereas a normally healthy stock tune car typically runs 20+.

We are fairly certain the car was run very easy, probably with a lot of city driving, and maybe even on 87 octane for a while. Pulling the plugs and inspecting the pistons showed a bit of excessive carbon buildup.

So we did the following:

(1) Added 1 bottle of Royal Purple Injector cleaner
(2) 1 bottle of Sea Foam intake treatment (and created lots of big smoke clouds). I recommend spraying it all in on a warm engine, then letting it soak for 15min or so.

After running through the tank of gas this way, KCLV would immediately shoot to 22! Initially I thought that the bottle of injector treatment improved the fuel quality, but even on successive fill-ups, the KCLV shoots right back up after reset.

So bottom line is that if you have a higher mileage car, or the background of your car is unknown, this procedure is probably a good thing to do. I was even surprised with the results.

We haven't tried it on an ISF yet, but I don't see why it wouldn't be effective, as carbon buildup affects most engines similarly, and causes increased knock correction.

I would recommend doing the Sea Foam treatment before changing oil, as some of the solvent may make its way to the oil.

-Rafi

 

So Rafi, you let the intake manifold suck up the seafoam to clean off the carbon? I've done this in previous cars with great results, haven't thought about it with my IS-F since carbon buildup is usually not a big issue (I think).

 

I've used Sea Foam in the past and I think have had satisfactory results. My wife worked 30 years for UPS, knew the shop mechanics real well and they routinely added it to the fuel tanks which were mostly diesel. They would never have used it unless it did something.

I add it to the fuel, but in our case, I wonder why we would not pull the plugs and add it directly into the combustion chamber. Providing, of course that we were sure that carbon had built up there. I'd let it soak for awhile before starting the motor.

Loren

 

Will using a higher ron fuel value remedy this problem or are there other issues that come to play to cause threat lower value?

I know here in NZ with my Supra and eventually when I get an F my car will run on a min.98 grade fuel.I would'nt touch anything less.

 

Definitely doing this even though I only have 57K miles.

 

I have been running blended e85 recently and I'm wondering if it helps clean off the carbon also.

 

I have been blending E85 but will do this today.

 

Well, the PCV sucks in oil, just pull your PCV pipe and you will see its wet.

Higher octane certainly is a major help. Its certainly harder to tune on 91, but in this case, we were running a known good 93 source and KCLV was still not going up.

You could add it to the combustion chamber directly, but you wouldnt be cleaning the valves, and also I think its more effective when the engine is hot.

Rafi

 

I have pulled the tube off and seen oil on the barb, I didn't even think about that. I am meaning to get an AOS in the near future.

 

Can someone post a pic of where we spray the seafoam in on the ISF engine? I think that would be helpful.

 

I'm thinking if its spray, you spray it into the throttle body opening. if its the liquid, you have to suck it up with a vacuum line with the engine running. PCV line would be perfect for this i think.

 

yeah thats why I was asking for a pic or more clarity. I found a couple youtube videos and some people were spraying it into the throttle body and others were using vacume lines to suck it up. Im curious what Rafi recommeds.

 

Why not just use water? I do that all the time before a teardown to minimize the carbon clean up. It generates the same clouds of "smoke" seafoam does and it isn't a hydrocarbon that will dilute your oil.

The key to any of these methods is to get the engine really hot. It's the sudden temperature differential that makes the carbon come off.

The other thing you'll likely find with KCLV challenged engines is the deck height isn't optimized so the squish is too great. Squish height is the most critical dimension in a performance engine because it alone determines octane requirements. Get the squish right, and the engine will run ridiculously high compression on crappy fuel. Get it wrong and you'll be scratching your head for years trying to understand why the engine won't run on anything less than the most expensive high octane fuels. Manufacturing tolerance for squish almost invariably puts it in the less than ideal range, and sometimes in the far from good range.

 

Do it like this

 

Just saw this video. Looks like the same method as Mahcah.