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2016 Kia Sorento SX V6, 2014 Kia Cadenza Premium
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210 Posts
Thanks for the info, Steve. I guess what I'm getting at is if a solution like this spray is sufficient or if there are more steps recommended to removing the carbon buildup?
Small point here but what can collect on the back side of the valve is not carbon. Carbon is a by product of combustion. What is collecting on the back side of the valve comes from oily deposits generated by a crankcase breather. In a non-GDI engine these deposits would be washed off by the air/fuel mixture passing the valves. It would be easier to clean them before it gets too bad from many miles of in-attention.
 

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2017 Sedona LX
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1 Posts
I performed this service myself using CRC Intake Valve Cleaner the other day. My 2017 Sedona has 39,000 miles.

I removed the air filter and inserted the spray nozzle past the MAF sensor, spraying in quick bursts. It took about 15-20 minutes to empty the can. I used a pedal depressor ($18 on Amazon) to hold the engine at 2000rpm.

The engine would noticeably slow while spraying, then recover.

After turning the engine off and letting it sit for an hour ("heat soak"), I took it for a drive to get the recommended 10 minutes of highway driving for completing the process. I live quite a ways from a highway, so it ended up being a 55 minute drive (20 mins of a highway, 20 mins going 35-55mph, and 15 minutes at slow speeds in stop-and-go).

Driving to the highway, the engine had a noticeably clunky idle with some pinging and acceleration was impaired. My guess is that residual cleaner in the intake was still making its way through.

By the time I got off the highway, it was back to running smooth.

No engine lights appeared, and I did not notice anything coming out of the exhaust pipe. I kept the Eco setting off.

I achieved 26.9mpg for this drive, which is significantly better than usual.

Changed the oil 2 days later.

Have no idea if my valves are clean, but it was cheap, easy maintenance and seems to have helped mpg, at least in the short term.
 

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'15 Kia Sedona SX
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176 Posts
Thanks! Inserting tube past MAF seems easier than trying to figure out which hoses etc. to remove.

Anyone disagree with the above method (not asking whether you agree with valve cleaner itself, yeah?)?

Isn't a throttle depressor just a broomstick handle cut to size (or adjusted with a brick)?
 
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