Is it necessary? Some engines do just fine with them never being touched.
Carboned Intake Valves
- Thread starter Al
- Start date
CRC doesn't do much, you need mechanical scrubbing. If you can't walnut blast, I heard scrubbing by hand with some nylon tool (i.e. zip tie on a stick) might redneck enough carbon out.
The only ones that seems to do ok without dual injection are the ones keeping the intake values at 400C to burn those carbon off (i.e. Skyactiv G). Think of it as self cleaning oven temperature.
Dry ice is not needed if you are not worried about a bit of walnut residue like engine. Usually after walnut blasting they spray compress air and vacuum out the remaining media anyways. It is not sand and any tiny amount remaining would just burn up. I have seen people dry ice blast industrial equipment that can't tolerate any residue, but not engine.
The only ones that seems to do ok without dual injection are the ones keeping the intake values at 400C to burn those carbon off (i.e. Skyactiv G). Think of it as self cleaning oven temperature.
Dry ice is not needed if you are not worried about a bit of walnut residue like engine. Usually after walnut blasting they spray compress air and vacuum out the remaining media anyways. It is not sand and any tiny amount remaining would just burn up. I have seen people dry ice blast industrial equipment that can't tolerate any residue, but not engine.
There is no effective solution for DI only other than mechanical removal (walnut/safe media blasting). I had two DI only cars back in 06’, a FSI VW and a N54 BMW. You would think 20 years later we wouldn’t still be having the need for this discussion. There isn’t any easier or cheaper solution that works. Chemical solutions that actually touch the back of the valves (running anything thru the fuel system does nothing for obvious reasons) don’t remove ALL, if any, of the carbon. When you don’t remove all the carbon you merely leave a surface for more carbon to build up and carbon is going to build up and need servicing much earlier than had you done it the right way and walnut blasted the surfaces COMPLETELY clean. If you buy a DI vehicle without port injection BUDGET WALNUT BLASTING at least every 40-50k miles. For most people that’s about every 3 years of a few times over the time you keep a vehicle. If you could “occasionally” spray some potent chemical behind the valves or thru the fuel system do you think the manufacturers would have started adding cost reintroducing port injection to DI engines instead of just adding a factory maintenance service they could charge you for?
Does anyone have a dyno test before and after a walnut blasting session? If carbon was disruptive enough to require walnut blasting, the difference should show up. 
Heavily carboned valves should show up in the misfire counters even if you don’t have a misfire code. Would be interesting and very inexpensive to do a before and after on those.Does anyone have a dyno test before and after a walnut blasting session? If carbon was disruptive enough to require walnut blasting, the difference should show up.
Also I seriously doubt any OEM is going back to MPI.
No way of knowing. Every reason to believe it is occuring.
No clue what the SkyActiv-G runs the valves at, but I've seen plenty of evidence that at least the USDM ones (which runs a lower temp thermostat than the rest of the world) that carbon build up does happen with them anyway
Fuel has nothing to do with intake valves developing carbon on a GDI engine.
fuel detergents probably not but fuel octane can.
You must be new to engine tech?
When DI came around valves started carboning up b/c the FUEL injector was no longer located behind the valve to keep it clean. Top Tier + has everything to do with helping with fuel & DI engine carbon issues (hence my suggestion you quoted to use TT+ in DI engines).
Please study up on the subject.
Top tier is a marketing scheme. I have read the TT+ literature and I don’t recall anything about valve carbon, only keeping GDI injectors cleaner?
How can a fuel additive keep the back side of valves it never touches cleaner?
You're welcome to share your opinion.
PCV reburn etc. There will be touching via the exhaust valve. Keeping the injectors clean will keep the combustion cycle cleaner= less particulate emission. Cleaner combustion = cleaner valves.
Here's a Ford 2.3L test. These aren't just claims that aren't backed up with testing.
Marketing scheme by definition, not opinion.You're welcome to share your opinion.
PCV reburn etc. There will be touching via the exhaust valve. Keeping the injectors clean will keep the combustion cycle cleaner= less particulate emission. Cleaner combustion = cleaner valves.
Valve carbon is primarily from pcv and other oil burn. Gdi injectors are high pressure in the cylinder. Closed loop control, incomplete fuel burn does not cause valve carbon. Physics- not opinion.
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Feel free, it’s well documented. You offer nothing additional so oh wellI'll leave it here for others to read...
You've made up your mind.
Yea. You got that rightI'll leave it here for others to read...
You've made up your mind.
This is from top tier’s webpage, under gasoline plus standards. I don’t see anything for GDI valve cleaning, just DI injector cleaning. It says so right at the top in section 1.1.
https://www.toptiergas.com/wp-conte...eposit_Control_Performance_Standard_Rev_G.pdf
https://www.toptiergas.com/wp-conte...eposit_Control_Performance_Standard_Rev_G.pdf
Is this referring to the ASTM D6201 test? If so, that’s using a mid 90s MPI Ford Ranger and isn’t relevant for a GDI engine.You're welcome to share your opinion.
PCV reburn etc. There will be touching via the exhaust valve. Keeping the injectors clean will keep the combustion cycle cleaner= less particulate emission. Cleaner combustion = cleaner valves.
Here's a Ford 2.3L test. These aren't just claims that aren't backed up with testing.
View attachment 349220
Or is there a newer IVD test on a 2.3 EB GDI engine?
I disagree.
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