continued carbonization of intake

[TexasTea]

hi all, about a year or year-half ago i added a PCV catch can to my PCV system and decided to go ahead and pour a solvent into vacuum line while i had the system disassembled.

1 16 oz container of B12 chemtool i think it was, cleared up some spark knock that would always occur at the upper rev range.

fast forward to about 1-2 months ago and it slowly but surely started creeping back in. v8 motor silverado 5.3 2004, 165k, never had the intake cleaned prior to the vacuum line treatment, but it cleared up the spark knock even in Texas' hot summer months. No ping, no spark knock.

I try to be very fastidious on my maintenance and keep my oil changed regularly and in good condition.

I dont think the engine has any sludge in it.

Where is this carbon build up coming from? could it have been the muck introduced through the PCV? (prior to catch can installation) I've had it on for about 2-3 oil changes now and it hasnt collected much if anything.

The only area where I "skimp" would be cheap gas. I buy generic, budget gas from gas stations, walmart, anywhere that has it cheap.

The pumps are always in good condition though. (I guess its not the pumps but rather the tanks to be worried about)

A member on here recommended "kan o kroll" in the gas tank to resolve future spark knock issues so thats the route i'll be taking im just wondering...after such a direct treatment and ping free driving for year and a half,,,why am i now back to having spark knock when i've only become MORE fastidious in my maintenance intervals especially when it comes to oil.

 

[itguy08]

Originally Posted By: TexasTea

Where is this carbon build up coming from? could it have been the muck introduced through the PCV? (prior to catch can installation) I've had it on for about 2-3 oil changes now and it hasnt collected much if anything.


Cans do next to nothing for intake deposits. Ask the VW guys how they worked out for their GDI issues, it didn't.

Spark knock - check the basics - plugs, wires, COP, etc. Then look at the knock sensor - if it's functional it will not ping.

 

[dgcamero]

I know two people who either had or have a 5.3L that pinged really bad...and a new catalyst or two fixed it on both of them. One of the truck's cat(s) went at around 120k, and the other at about 200k. I know they both went aftermarket, so the cost wasn't unreasonable. Something to look into anyway. Hopefully it's not that complicated though!

 

[Ducked]

Originally Posted By: dgcamero
I know two people who either had or have a 5.3L that pinged really bad...and a new catalyst or two fixed it on both of them. One of the truck's cat(s) went at around 120k, and the other at about 200k. I know they both went aftermarket, so the cost wasn't unreasonable. Something to look into anyway. Hopefully it's not that complicated though!


How would that work? I've got no experience of catalysts, but they are fairly far downstream of the combustion chamber.

Only way I can see is if EGR came from downstream of the catalyst, but I don't THINK it does?

 

[andyd]

hEH Heh . My 528e is prone to carbon build up BMW's cure was a blast with walnuts shells. BMW enthusiasts cure is an Italian tune up Try a 50 mile in 3rd at 75-80 mph.

 

[benjy]

prolly most modern DI engines are prone to carboning, some sooner than others as manufacturers are MUM as they do not want to $$$$. generally turbo'd engines + slow short trips are said to be the worse. beside an older port injected engine the few port + DI engines are the only safe ones!!!!

 

[bvance554]

Do you know there is carbon build up, or are you just guessing based on the symptoms?

 

[oldhp]

"The only area where I "skimp" would be cheap gas. I buy generic, budget gas from gas stations, Walmart, anywhere that has it cheap."
I think you answered your own question here. How much are your saving using "cheap" gas vs. Top Tier gas, can't be much. Have you tried Techron fuel treatment??? When where the spark plugs last changed???