Remedy for carbon buildup on intake valves? holding RPMS at 3k + for min 20 minutes?

[someonesomewhere]

Keep at redline for an hour. That'll totally get rid of it.

This works more consistently if you disable the rev limiter via tune.

Don't be afraid, when the guts of the cat start coming out liquefied, you must persevere and keep going!

This is foolproof, works 100% of the time to resolve intake valve deposits.

 

[oil pan 4]

Saw this posted on Reddit, the poster referenced a VW patent that showed that DI buildups could be removed if a warmed engine was held at 3000 RPM for at least 20 minutes. Idea was that if the intake valves were allowed to get warm enough for long enough the buildup would be ingested into engine and burned away. Other aspects of the VW patent were suggesting that if engine oil contained enough carbon dissolving solvents the DI buildup might not be an issue.

With modern cars trying to keep revs so low with either 8 or 10 speed transmissions or CVT, the average car spends very little time at 3k RPM and it would be only the BITOG type that would force this routine onto their car for the possible burn off of DI gunk.

What say you?

Oh yes another VW oil spec will fix their problems...
(I figured out along time ago it's not the oil)

 

[Soft Cars]

3000 RPM without a load on the engine is a bad idea.

 

[shortyb]

3000 RPM without a load on the engine is a bad idea.

This.

Never has worked on any of my VWs. Like @TiGeo mentioned, hard running DOES help mitigate deposits some, however, doesn't clean existing deposits nor help keep all from forming. Low SAPS oils may/may not help, but keeping the breather system operating properly is about the best you can do to help with IVD in these engines. Earlier gens were worse than newer ones, but they still get deposits. A good walnut blasting is the best bet for restoring a squeaky clean intake side.

 

[TiGeo]

This.

Never has worked on any of my VWs. Like @TiGeo mentioned, hard running DOES help mitigate deposits some, however, doesn't clean existing deposits nor help keep all from forming. Low SAPS oils may/may not help, but keeping the breather system operating properly is about the best you can do to help with IVD in these engines. Earlier gens were worse than newer ones, but they still get deposits. A good walnut blasting is the best bet for restoring a squeaky clean intake side.

It's just a maintenance item at some point if you keep your vehicle long enough.

 

[Kantaro]

I recall reading this nearly 20 years ago and looked it up to verify that it was part of a patent filed in 2002 and published in 2005. The gist of it is that it was proposed that getting the intake valves hot enough could burn off carbon deposits caused by DI. I'm assuming it isn't very effective, otherwise other procedures such as walnut blasting would not be required.

US6866031B2 - Direct injection internal combustion engine - Google Patents

An internal combustion engine, especially an Otto engine, with intake valves and with a fuel injector, which is arranged and designed so that it injects the fuel directly into a combustion chamber of working cylinders of the internal combustion engine. At least in the region of the neck, the...

patents.google.com

 

[RAR]

My Mini Cooper S is direct injection, and gets the carbon crud build up.

I tried the injection of GDI cleaners into the intake, and it did little. Still a lot of carbon.

The only sure fire cure is fine (not coarse) walnut shells fed through a blasting rig. And, a shop vac attachment that fits over the intake opening with a hole for the wand from the blaster. Harbor Freight sells walnut blasting media for under $30.

I’m fortunate that I have a good air compressor and the vac attachment specific to the Mini so I can do this yearly. The blaster can be a small sand blaster (DO NOT use sand on your head! Unless you’re trying to destroy it), but I got a Harbor Freight media blaster which is merely a plastic blow molded container with fittings for the air hoses. You can probably make one from a 5 gallon pickle bucket (a.k.a., “Homer” bucket) for less if so inclined. I probably would now.

That’s way cheaper than paying someone to do it. I’ve paid in the past on my 535xi and it was $700. .