Yup. If done improperly it can cause problems. Usually not but yea.

 

So I got the Car back..............

Misfire on all cylinders, mostly #4. Did Compression test, 120psi on all cylinders. Opened Intake, Major Carbon build up on all valves and #4 Cylinder port was covered/obstructed by carbon build up. Removed all valves and head. Hand cleaned all valves, and cylinder head. Reinstalled with New seals, Reinstalled head and new head gasket, also replaced head bolts. New oil and coolant.

Tech showed me before and after pics. It was gross. Inside the head and the valves were caked and I mean caked in brittle carbon. He said he was surprised nothing on the cylinder walls were damaged. There is a serious flaw with direct injection as it sits. They had the same Cobalt SS/TC I mentioned a few posts back, brought back in there at the same time with the exact same issue and codes being thrown. Same mileage as my car. The thought they fixed his issue and the kid had the car back for 30mins after they fixed his broken lifter throwing the same missfire codes as mine. They were going to clean the top end by hand like they did with mine.

I was chatting with the tech and I asked him what can be done to prevent this and he said at this point nothing. He said he would prolly see me in a year or 2 for the exact same issue. Its one of the flaws of direct injection.

So the SS is gone even if I have to take a bit of a hit on it for a trade in. He said it would have been a pretty nasty bill had it not been covered under the power train warranty. Which if it takes another 50000kms to happen again the car will be out of warranty.

Going car shopping today.

 

Interesting read
But. Makes you wonder about others that have 80,90,even 100k miles on their SS's and haven't had any issues related to this.

 

I am a firm believer if your going to do an inj service, do it atleast every 30k miles. Its cheap and easy. Cant hurt anything. And if your unsure if its been done, dont do a full one first and have the car on, and every few minutes rev it. Dont let it build up, or else this can happen. I will bet the tech hooked it up and walked away for 20-30 min and came back.

Smh can only do that if the car is clean :p but hopefully they will warranty or atleast give a discount for their incompetence. :) at my shop we do it my way. Lol i taught my techs the right way.

 

Have had the car back for a week. Car has been running much better. Much better throttle response and it pulls like a freight train in the top end of the power band now. I'm really surprised how much better the car feels. It felt very sluggish prior to having the carbon issue sorted out.

 

Not buying the carbon build up idea when it was all valves that were mucked up...since this is a turbo and there have been instances where others have noticed /complained of excess oil coking because its pulling oil thru the intake tract..oil in the turbo..oil in the intake manifold and so forth..Im think a better look at the PCV system is in order and possibly a catch can to prevent this being a repeat..some motors act better then others so theres always going to be an extreme on either side of normal, which might be why there hasnt been a rash of this problem showing up....just a thought.

 

I agree with the PCV system needing an overhaul. It was def carbon build up though. I saw the pics. Here is a link to some pics which was what my insides looked like. I'm sure oil blow by has a big part in what is happening. Regardless your motor is not going to run right if it looks like this........
http://drivegeek.wordpress.com/2011/...nd-a-solution/

My issue is I have had 2 previous turbo cars that pulled oil thorugh the intake / blow by and never used a catch can nor had an issue. My Mazdaspeed 3 was also a DI motor and those were very sensitive to the same issue. I beat on that car hard though and never had an issue which I'm sure did its job of burning up some of the deposits. I'm sure if any SS owner pulled there top end apart they would be shocked at what they saw. I think one of the main issues is I have never really beat on this car.

 

I would imagine something like a meth injection kit, or 5th injector kit would help prevent this. Having fuel hit the intake valves and all. But if you want to stay stock, obviously it's pointless.

I know there are OEM's using a 5th injector type setup on their DI cars to prevent these exact issues. I believe Toyota might be one of them that does it on their 4 cylinder DI cars.

I am afraid to even look at mine, bought it used with 61k miles, and now up to 76k. I can feel it missing sometimes at idle, but so far no codes. I can see myself buying a spare LNF head in my future, and just keeping it on hand in case mine gets this bad.