My experience with PI and carbon build up

[Acadia18]

so is there anything that has been proven to reduce/reverse carbon buildup on the valves?

Walnut blasting your intake valves.

 

[Diggs24]

Don’t go big turbo or run tons of boost.

 

[The Dude]

so stock vehicles don't have issues with it?

 

[Diggs24]

so stock vehicles don't have issues with it?

not for a long time

 

[The Dude]

oh well. too late now

 

[jimlloyd40]

so MPI doesn't make a substantial difference then, what about WMI?

I missed who said that MPI doesn't make much difference.

 

[The Dude]

look a couple of posts up. MPI seems to keep the valve stems cleaner, but the back of the valves are staying pretty gross. Again, in the specific photos above.

 

[jimlloyd40]

I guess that kills the catch can helping theory ??

Not for me it doesn't. I'm still a firm believer in the Spulen OCC because of the borescope at 50K.

 

[jimlloyd40]

look a couple of posts up. MPI seems to keep the valve stems cleaner, but the back of the valves are staying pretty gross. Again, in the specific photos above.

Has anyone with MPI that's had it long enough to see pictures after similar mileage to before they installed MPI?

 

[anotero]

Slightly off topic: is browning of the top piston surface fine? I took a peek at them when changing spark plugs at 70k+ miles. Nothing bad, not gunky, just a thin layer. Can still make out the circular pattern the pistons originally came with. Interestingly, piston in cylinder 4 had the least amount of this buildup, and was practically spotless and shiny.

 

[jimlloyd40]

Slightly off topic: is browning of the top piston surface fine? I took a peek at them when changing spark plugs at 70k+ miles. Nothing bad, not gunky, just a thing layer. Can still make out the circular pattern the pistons originally came with. Interestingly, piston in cylinder 4 had the least amount of this buildup, and was practically spotless and shiny.

Do you ever use a fuel system cleaner in your gas?

 

[anotero]

Do you ever use a fuel system cleaner in your gas?

Used it twice over the last almost 80k miles. First time (before peeking at the pistons) was a long time ago, maybe 20k miles ago. Why?

 

[jimlloyd40]

Used it twice over the last almost 80k miles. First time (before peeking at the pistons) was a long time ago, maybe 20k miles ago. Why?

Just curious if the tops of the pistons had the brown color on the pistons if you were using a fuel system cleaner.

 

[anotero]

Just curious if the tops of the pistons had the brown color on the pistons if you were using a fuel system cleaner.

Are yours nice and shiny?

 

[Diggs24]

Slightly off topic: is browning of the top piston surface fine? I took a peek at them when changing spark plugs at 70k+ miles. Nothing bad, not gunky, just a thin layer. Can still make out the circular pattern the pistons originally came with. Interestingly, piston in cylinder 4 had the least amount of this buildup, and was practically spotless and shiny.

70k thin film is normal. Cyl4 being cleaner is a bit odd. Could be because it has best compression and less blowby than the others. Could be fueling related but I'd think you'd see other signs of that.