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jrmarshall01 said:
Is oil sludge more of a problem for engine performance than carbon deposits? How worried should we Enclave owners with DI engines be about this? If this is a worrisome issue, installing a pcv oil mist can sounds beyond most owners capabilities...and does it require frequent maintenance on its own?
I think that depression/reservoir in the rubber coupler is designed to catch the oil. I cleaned mine at 70k or so and it had no more oil than that in it. It would make sense to induce a small amount of oil into the conbustion chamber that way from an emission standpoint. My throttle plate was pretty clean also with that mileage.
 

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I changed my oil on Dec 26.
I cleaned the TB and the factory catch can.
This is the oil that was in mine. About 2 Tablespoons worth
I think this is about 10,000 worth of buildup.
It was all confined to the reservoir- none- on TB or anything else

 

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silvervettes said:
I think that depression/reservoir in the rubber coupler is designed to catch the oil. I cleaned mine at 70k or so and it had no more oil than that in it. It would make sense to induce a small amount of oil into the conbustion chamber that way from an emission standpoint. My throttle plate was pretty clean also with that mileage.
I agree. Last year I found oil in the Throttle Body. After the dealership re-flashed my ECM, the problem went away. This summer my Throttle Body plate was clean, and there was a small amount of oil in the reservoir, but none near the MAF. I'm not sure I need to install a PCV catch.
 

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Not to sound or be dumb... What is meant by DI?
 

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cfedor said:
Not to sound or be dumb... What is meant by DI?
Direct Injection. Only applies to 2009+ Model Years of the Acadia, Enclave, Outlook, & Traverse. Your '08 has Port Injection, so the carbon build-up on the intake valves is not an issue on your engine.
 

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XRDreamliner said:
Direct Injection. Only applies to 2009+ Model Years of the Acadia, Enclave, Outlook, & Traverse. Your '08 has Port Injection, so the carbon build-up on the intake valves is not an issue on your engine.
Sometimes, and in some ways, it is better to have the older tried and true design. ;)
 

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Sometimes the more you read, the more confusing things are. XR, you basically stated on January 2, that in a DI engine the fuel injects directly into the combustion chambers and never "washes" the backs of the valves (or words to that effect) How then can Techron clean the backs of the valves if it never reaches the valves? I'm not trying to be a wise guy here...I'm genuinely interested.
 

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XRDreamliner said:
Direct Injection. Only applies to 2009+ Model Years of the Acadia, Enclave, Outlook, & Traverse. Your '08 has Port Injection, so the carbon build-up on the intake valves is not an issue on your engine.
Thank you, XRDreamliner!
 

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WPNSO said:
This summer my Throttle Body plate was clean, and there was a small amount of oil in the reservoir, but none near the MAF. I'm not sure I need to install a PCV catch.
I would hope you'd find no oil near the MAF, because it is upstream of the PCV port on the intake plenum.

As for whether you need a catch can or not - if you regularly maintain your engine, and in the case of several members, remove the intake to clean the intake of oil, then a catch can is a good idea. A catch can not only catches the oil heavy enough to settle out which appears in the intake "trough", it also catches the oil mist that is carried by the crankcase blow-by gases by slowing down velocity of these gases (which would otherwise condenses on the walls of the intake manifold, and ultimately the intake valves, which contributes to the carbon formation).

Here's a great link that explains what makes up the blow-by gases in the PCV system, and even disucsses the catch can:

http://www.106rallye.co.uk/members/dynofiend/breathersystems.pdf
 

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KCorey said:
Sometimes the more you read, the more confusing things are. XR, you basically stated on January 2, that in a DI engine the fuel injects directly into the combustion chambers and never "washes" the backs of the valves (or words to that effect) How then can Techron clean the backs of the valves if it never reaches the valves? I'm not trying to be a wise guy here...I'm genuinely interested.
You're right, it can't. In fact, I disagree with GM in its bulletin on this issue... they imply the use of fuel cleaner will somehow control the future formation of carbon deposits in a DI engine. Techron will only help clean the fuel injectors themselves and the combustion chamber in a DI engine, but NOT the back of the intake valves.
 

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XRDreamliner said:
You're right, it can't. In fact, I disagree with GM in its bulletin on this issue... they imply the use of fuel cleaner will somehow control the future formation of carbon deposits in a DI engine. Techron will only help clean the fuel injectors themselves and the combustion chamber in a DI engine, but NOT the back of the intake valves.
Except on the non-DI engine in the 2008's
 

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XRDreamliner said:
You're right, it can't. In fact, I disagree with GM in its bulletin on this issue... they imply the use of fuel cleaner will somehow control the future formation of carbon deposits in a DI engine. Techron will only help clean the fuel injectors themselves and the combustion chamber in a DI engine, but NOT the back of the intake valves.
How do you know that when the fuel with additives combusts that what is left has no cleaning power?
 

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XRDreamliner said:
I would hope you'd find no oil near the MAF, because it is upstream of the PCV port on the intake plenum.

As for whether you need a catch can or not - if you regularly maintain your engine, and in the case of several members, remove the intake to clean the intake of oil, then a catch can is a good idea. A catch can not only catches the oil heavy enough to settle out which appears in the intake "trough", it also catches the oil mist that is carried by the crankcase blow-by gases by slowing down velocity of these gases (which would otherwise condenses on the walls of the intake manifold, and ultimately the intake valves, which contributes to the carbon formation).

Here's a great link that explains what makes up the blow-by gases in the PCV system, and even disucsses the catch can:

http://www.106rallye.co.uk/members/dynofiend/breathersystems.pdf
I understand what you're saying; but, as long as there are no pools of oil in my Throttle Body, I'm not going to bother installing extra catches. When I change the plugs (in a couple of years), I'll clean everything out with Sea Foam (I've had great luck with that in other vehicles) and depending on how much carbon has built up, will re-visit the idea of installing catches.
 

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XRDreamliner said:
You're right, it can't. In fact, I disagree with GM in its bulletin on this issue... they imply the use of fuel cleaner will somehow control the future formation of carbon deposits in a DI engine. Techron will only help clean the fuel injectors themselves and the combustion chamber in a DI engine, but NOT the back of the intake valves.
What he says is true

But I read somewhere on strategies that GM was using to help control Carbon buildup.
In short-- it said that GM was altering the timing of the opening/closing of the valves.
They had set it up so that a valve remained opened just long enough--- that when fuel was sprayed in the combustion chamber-- some sprayed fuel made it out of the chamber right before it closed- and landed on valves or surrounding area....
But this wasnt large amounts of of fuel to wash the valve... but enough to help somewhat.... and thats why I the bulletin mentioned above sort of makes sense as to why they run Techron during the procedure....

Now-- Ive looked all over the place for this info I read and cant find it--- I wish I could find a forum where GM DI engine engineers hang out-- that I could ask about this to verify....
 

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Naw, I can't agree with this...this would only lead to a rough-running engine. And something that would outlast the ignition of the fuel and then exhaust itself would only make the spark plugs foul up. This just from some kind of thinking. Any engineers out there who could help clear this up?
 

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KCorey, sorry to go off topic a bit, but did you ever have any engine issues with you Tribeca? At over 86,000 miles, mine seems to idle as smoothly as the day I got it, but I want to get a heads up on anything that you may know about.
 

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You guys are forgetting about the 2nd PCV line off the head closest to the firewall which dumps directly into the top of the intake plenum.
 

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Discussion Starter #78
I wanted to report that since my valve heads were "cleaned", three weeks ago, I have noticed an improvement in gas mileage of about 1 to 2 miles per gallon , and a significant improvement in the acceleration and pickup on the vehicle. Guys, you may not believe it , but carbon deposits are happening on these Enclaves. I agree the top tier gas or unbranded gas has little to do with this issue as xrdreamliner says the gas is not near the valve heads.
 

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Were your plugs fouled/carboned up like the guy's on the other forum? I didn't look at the valves when I did my coil paks, but I did replace the plugs then and it was at 68k and the plugs looked perfect with really no visible wear and certainly not all caked up. What type of driving do you do? % highway % local
 

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Discussion Starter #80
No mention was made of the plugs during the dealer servicing, so I am assuming they were fine or not examined. I have only 32k miles on my 2010 awd cxl . I do about 75 per cent in town driving and 25 percent highway. The cleaning procedure took a couple of hours, I don't think the valve heads were that bad or else it would have taken longer.
 
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