from what I gathered from the merged thread, the thorough cleaning provided by the dealer (there is a tsb) should be done as often as required while under warranty and then there are other less thorough options that can be performed at a garage annually to clean the tops of the valves.

 

Given the issue isn't unique to the 250 (the other longer thread on it mentions a bunch of other DI-only cars that have it from other vendors) I'd say yeah. Seems inherent to the current-gen design of DI-only motors.

 

Kurtz is right, the fuel never touches the part, so it can never wash away the carbon buildup. However, the carbon build up comes from the gas, so using crappier gas will just make the carbon build up faster. Using 91 or higher octane gas will still give you carbon build up, but at a much slower rate.

 

Lexus tech's are using this GM product for the top end cleaning of 250's. Your car will smoke like crazy for about 30 minutes but it does a good job on the valves.

 

In response to the "cheap" gas statement by Think Twice... below you will find an excerpt from an article found in Smart Money Mag Online. It alludes to the fact that the gas you get at the small mom & pop station is the exact same as you get at the big boys so there is no real concept of "cheap" or "low quality" gas anymore. Now...I understand that there are some other distinguising factors such as "Top Tier" fuel [Sinclair et al] but that's another conversation.

So among normal everyday gas the only thing that stands out would be octane. By the same token, I usually shy away from the mom & pop stores because no matter what they say in the article I still can't get past the look and feel of what you would consider a lower end gas station...I guess we all have our prejudices!

Lastly, I had the top engine clean done several months back and I haven't had any idling issues since. I typically run 91 or 92 octane my car.

Best of luck to all of us with this issue!!!

 

In response to the "cheap" gas statement by Think Twice... below you will find an excerpt from an article found in Smart Money Mag Online. It alludes to the fact that the gas you get at the small mom & pop station is the exact same as you get at the big boys so there is no real concept of "cheap" or "low quality" gas anymore. Now...I understand that there are some other distinguising factors such as "Top Tier" fuel [Sinclair et al] but that's another conversation.

So among normal everyday gas the only thing that stands out would be octane. By the same token, I usually shy away from the mom & pop stores because no matter what they say in the article I still can't get past the look and feel of what you would consider a lower end gas station...I guess we all have our prejudices!

Lastly, I had the top engine clean done several months back and I haven't had any idling issues since. I typically run 91 or 92 octane my car.

Best of luck to all of us with this issue!!!


3. “My gas isn’t better for your car; it’s just more expensive.”

Oil companies spend lots of money explaining why their gas is better than the competition’s. Chevron’s gas, for example, is fortified with “Techron,” and Amoco Ultimate is supposed to save the planet along with your engine. But today more than ever, one gallon of gas is as good as the next.

True, additives help to clean your engine, but what the companies don’t tell you is that all gas has them. Since 1994 the government has required that detergents be added to all gasoline to help prevent fuel injectors from clogging. State and local regulators keep a close watch to make sure those standards are met; a 2005 study indicated that Florida inspectors checked 45,000 samples to ensure the state’s gas supply was up to snuff, and 99 percent of the time it was. “There’s little difference between brand-name gas and any other,” says AAA spokesperson Geoff Sundstrom.

What’s more, your local Chevron station may sell gas refined by Shell or Exxon Mobil. Suppliers share pipelines, so they all use the same fuel. And the difference between the most expensive brand-name gas and the lowliest gallon of no-brand fuel? Often just a quart of detergent added to an 8,000-gallon tanker truck.



Read more: 10 Things Gas Stations Won't Tell You - Spending - Rip-offs - SmartMoney.com http://www.smartmoney.com/spending/r...#ixzz1KkixluC7

 

^^^ I read the article above, but not too sure how much I buy into it. There has to be a reason some no name gas stations charge MUCH less per gallon than a brand name gas station. I just have a feeling some of them water down the gas. I guess it's a trust issue.

 

No additives (like this or others) is going to help. Unless you remove the valve covers and pour this OVER the valves. How is this stuff going to reach the valve seats from inside the cylinder?!?

 

Ok so question on the carbon build up. I've noticed a rough start (nothing major) from a cold start. Now granted I'm steppingf up from a winter beater 1997 ford escort and a 72 carbed datsun so this start up seems like nothing at all. But did notice once that at a stop light the car was idling and it was dropping near 500 rpm, almost like it was wanting to shut off. Quick blip of the throttle would fix it temporarily. Haven't had that problem since, so started to look on here and could be a carbon build up issue. Car is a 2007 with 39k miles on it.
Now for the question....
Whats the process for getting this looked at/fixed? I've taken it into the dealer several times for different problems, i.e. the aux port whine from a bad ground, the creaking rear windshield (that they have now damaged.....), thought the rear speakers weren't doing enough bass but that was normal and the dash/radio popping noise (dealer couldn't reproduce it so no fix yet...)
I just go in tell them I'm having a rough start up when cold and sometimes it idles oddly at stops, check it out? Or straight up tell them, hey im experiencing these problems, I need to get the carbon buildup checked out and cleaned.

 

Using a lower grade of gas does not cause carbon build up in our engines. The carbon is a by product of it being a direct injection engine.

 

You do NOT add the GM TEC to the gas tank. You use a pre-measured amount of the TEC, a small diameter silicone hose and disconnect a vacuum line to the engine. With the engine running, attach the silicone hose to the vacuum line and the other end to the pre-measured cleaner and let it slowly suck the cleaner into the engine. The engine will almost stall. When you are finished turn the engine off and let it sit for about 1-2 hours. Re-attach your vacuum line. Then start the engine. It will be difficult to start and when it does it will smoke like a chimney for about 20 minutes. Rev the engine several times. Drive it no more than 10 miles then change your oil. This is a very important step because you don't want to leave the carbon deposits in your engine.

 

If you read the tsb, this GM product is named and that is exactly what the techs do, they take apart the engine and let the valves soak in this stuff for an hour. I think a couple oil changes are also done etc etc.

All this stuff is in the merged thread

 

you really need to check out the merged thread since this applies directly to you as a 250 owner. There is a tsb so this cleaning should not cost you anything. Unfortunately, the cleaning is not a fix so you will experience it again. Best thing to do is get it done annually if you are under warranty and once you are off warranty, there are garages that do a less thorough cleaning that only takes an hour. If you do it annually as part of routine maintenance, then the buildup should be kept in check.

 

The problem you're going to have with the dealer is that it's very hard to replicate because it occurs so rarely and intermittently. It's really up to your dealership whether or not they want to do it without replicating the issue. I'd go in there with the TSIB printed out to hand them and let them know how rarely it happens.

 

I always use 93 AND just had the carbon build up thing done today as a matter of fact. I took it in for a routine oil change but got a call shortly after stating they were recommending my 30k carbon cleaning. Wasn't mandatory mind you, but recommended. I went for it. Why not after all? My dealer took the time to walk me through illustrated examples of exactly what they did. They should have all the info on hand to do the same for you. Ask about it, it was actually pretty interesting to see what all goes on during the process.

So...evidently it's just a rule of thumb for them to suggest it every 30k. Hope me typing all this jazz helps someone