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Discussion Starter · #1 ·
I'm concerned about the GDI engine's tendency to deposit gunk on the intake valves. I have a scope to throw in the manifold. I noticed some buildup. This was at about 18k. I tried to use CRC. It's cleaned the heck out of my intake and turbo, but seems to have deposited crud directly on to my valves. I think it's too early in the life if the motor to worry about this!
The first one is before cleaner. The second after. 3rd a few weeks after. Notice the crud on the base of the valve bulging out.
 

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Three words: Top Tier Gasoline
 

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Discussion Starter · #6 ·
Three words: Top Tier Gasoline
Will that make the EGR less sooty?
This is the problem with direct injection, the only things that hit the backs of the valves are filtered air and filthy EGR.
The top tier gas folks make some claims. I would imagine small bits of it end up on the other side of the valves and maybe in the blow by itself. Supposed to be good and removing deposits. Some claim results in two tanks. I'll move through that in a week or so and post some follow up photos
 

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GM's dabbled in direct injection engines for a while now.

I wish they had the dual-injection system that other manufacturers are now using, but they don't yet have any engines with that technology out in public. They have, however, set up the LE2 and their newer iterations of the 1.5T, 2.0T, 3.6 V6, and the V8 motors so that a little burst of fuel, under certain conditions, is squirted over the intake valve when it's open.

Looks like Sunoco is now in the top tier program (there are like 6 within 2 miles of me), so I'm going to continue running Top Tier gas and not worry about the intake valves until they become a problem. If I have to do 1-2 direct injection services on the car in its lifetime, I guess I'm ok with that. GM has a service procedure called out for the 2.4/3.6/3.0 with a 2-step BG solvent process to clean off the valves, which IMO beats the walnut shell blasting other mfrs call out. At least the GM engines don't seem to have nearly as many issues as early Audi/BMW engines.
 

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Discussion Starter · #8 ·
GM's dabbled in direct injection engines for a while now.

I wish they had the dual-injection system that other manufacturers are now using, but they don't yet have any engines with that technology out in public. They have, however, set up the LE2 and their newer iterations of the 1.5T, 2.0T, 3.6 V6, and the V8 motors so that a little burst of fuel, under certain conditions, is squirted over the intake valve when it's open.

Looks like Sunoco is now in the top tier program (there are like 6 within 2 miles of me), so I'm going to continue running Top Tier gas and not worry about the intake valves until they become a problem. If I have to do 1-2 direct injection services on the car in its lifetime, I guess I'm ok with that. GM has a service procedure called out for the 2.4/3.6/3.0 with a 2-step BG solvent process to clean off the valves, which IMO beats the walnut shell blasting other mfrs call out. At least the GM engines don't seem to have nearly as many issues as early Audi/BMW engines.
I put lots of miles on my car. I didn't expect to see that much build up already. I still get pretty good mileage, but it certainly isn't as punchy as it was when I got it.

I asked the guy at the dealer about it when I got service the other day, and he told me about the solvent cleaning they have. It's over $200. I think it's crummy that they would under engineer their cars and expect us to pay for it later.

I'll start running top tier on my next fill up and stick the camera back in there in a week or two to see if there's any improvement.
 

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Hope to your results. I plan on keeping my cruze until it dies or becomes unsafe to drive. I would assume similar deposits in a gen 1. I have a 14 with about 79k miles. Would hope I can avoid sending it to an early grave.
 

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Gen1 is not direct injection. Top Tier gas will not help with intake valves much. They need to just make a simple spot on the intake so anyone can just spray cleaner in when they need too. Like a simple screw that you remove.
 

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Discussion Starter · #12 ·
Doesn't the clogged valves also cause LSPI?
Every engine has it to some degree. Flaky carbon buildup in the combustion chamber lean conditions are probably more to blame. I would imagine that if some hot carbon from the valves made it in there it could.

Goopy valves slow air flow and can stick. If the carbon builds up around the edges, it can prevent them from making contact with cylinder head. This is the main way they dissipate heat. Also, a poor seal would cause leaks, lower compression and allow more soot to blow by the intake valves making things worse.

I'm on my first tank of Shell 93. Top tier has nothing to do with octane, but I figured it couldn't hurt. Like my gen1, it does seem to help with the hiccups, tho
 

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Discussion Starter · #15 ·
It's been about 1000 miles on Shell 93. I couldn't find anything to quote directly from shell about how long it would take to see results, but various other fuels clam to see progress in two tanks. Let's see what happend.

It's difficult to tell, at this point, weather anything has changed on the top of the valves. However, I don't necessarily see any new buildup in the manifold and the turbo seems cleaner than it was after using intake cleaner. I'll allow you to make your own conclusion. I'll keep using top tier just because and update periodically.
 

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I’m definitely seeing an improvement.

If I understand correctly you started with 18,000 miles on a non-Top Tier Gasoline, with associated build-up. Since then you’ve run 1,000 miles with a Top Tier Gasoline and have no increase in build-up, plus a just noticeable improvement in the prior build-up.

Based on this, one can conclude that:

1) It will require more than 1/18th the mileage to totally remediate existing build-up.

2) If a Top Tier Gasoline can remove deposits - then it is possible that consistent use of a Top Tier Gasoline from engine assembly would result in no gasoline-related build-up.
 

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I’d like to share this experience from 2007 on my Tahoe that had just turned 62,000 miles and went into the dealer for preventative maintenance. Quoted from another forum:

The technician also went to clean the throttle body, but found that it was in very clean condition. So clean in fact that he showed it to me and one of his colleagues. It has never been cleaned before and he wanted to know how it could have had so much mileage while remaining so clean. My only conclusion would be that I use Shell gas and it is rated as a Top Tier Gasoline. All that to say that he wouldn't clean the throttle body as he didn't believe in doing work that wasn't necessary.
 

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Discussion Starter · #19 ·
I’d like to share this experience from 2007 on my Tahoe that had just turned 62,000 miles and went into the dealer for preventative maintenance. Quoted from another forum:

The technician also went to clean the throttle body, but found that it was in very clean condition. So clean in fact that he showed it to me and one of his colleagues. It has never been cleaned before and he wanted to know how it could have had so much mileage while remaining so clean. My only conclusion would be that I use Shell gas and it is rated as a Top Tier Gasoline. All that to say that he wouldn't clean the throttle body as he didn't believe in doing work that wasn't necessary.
It seems counter intuitive that the BS they feed you on commercials actually works, but results are results. The car companies and oil companies worked together on this top tier stuff. I wish they would put a little "please use top tier fuel" sticker by the gas cap or something like that.

At this rate I'll double my mileage in no time. I'm going to keep cramming that little camera down there from time to time to check up on it.
 

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Since the fuel doesn't pass through the throttle body, I'd think driving style and the positive crankcase ventilation (PCV) system working better than usual would weigh a lot more towards a clean throttle body than fuel choice. Engine oil would also be a big factor as that's the residue that normally makes it into the PCV system and get sucked through the throttle body.

I like that the Top Tier gasolines have a requirement for enhanced levels of detergent but to play devil's advocate, it's also marketing company and maybe a non-Top Tier brand meets the same standards or better but don't want to pay their licensing fee. Out in California ARCO gas was widely ridiculed by performance crowd because it was cheap but they paid in and are now a Top Tier brand. Maybe they were always decent but had a perception problem.

From experience over the years I do like Shell and Chevron/Texaco additive packages but won't pay $.25-.30 cents more a gallon for it, especially in areas where there the base stock gasoline all comes from the same refiners.

A quality gasoline should help keep the intake valves on a port injection engine cleaner along with the combustion chamber, but it won't necessarily do a great job removing built up deposits over time. I normally worry less about the brand of gas and run a bottle of quality concentrated fuel system cleaner such as Techron with every oil change. There have been a lot of studies over the years showing a quality concentrated cleaner should help with clean-up way better and the specific brand of gas becomes less of a concern since federal and state standards require an effective amount of baseline detergent.

For newer direct injection-only engines? A great working PCV system and engine oil are most important (as some over time makes it past the intake valve seals and also vapors get into the the PCV system). The brand of gas or concentrated cleaners will only help with combustion chamber deposits. Without taking the intake manifold off and manually cleaning, a through-the-intake cleaner like Seafoam or similar manufacturer recommended cleaners is about the best you can do. Or a water injection kit and crank up the turbo boost. :grin:
 
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