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Discussion Starter #1
Hi,
I'm trying to figure out my sister's Cobalt. It's a 2010 2.2 N/A auto with 228k miles. She has had it 2 years, she bought it with 175k neglected miles. I have changed cabin filter, air filter (Wix), Plugs (AC Delco) coolant, trans fluid. Oil every 2500 city miles with some 5w30 Mobil Super Synthetic I got from AAP for 49 cents a quart. And cleaned the Throttle body. The car has chain rattle and throws codes PO 0010, P0 0011. The idle will fluctuate and slowly get worse like a vacuum leak. It will stall if you let it idle for more than a few minutes when it's hot. I clean the TB (Tons of Crap in it) and it's fine for a few months. I clean the TB and again (oily carbon) and it's fine for a few months. Rinse repeat..... Why? It doesn't use oil.
I've been wrenching for 20 years (I'm 34) I own a gas car and a diesel truck. I'm just trying to help my sister.
Thanks,
Dustin
 

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With that many miles it may be blow by caused by worn rings If you have a compression tester pull the fuel pump fuse or relay and see what numbers you get, You're looking for even numbers more then a specific number. You can search for what it should be close to. If it's very uneven from cylinder to cylinder that's not good. So if it's similar to my Saturn 2.2 the valve cover has a hose going right to the intake hose about a foot from the throttle body, It's probably sucking all the excess oil vaper caused by the ring blow by making higher crankcase pressure. Just a guess. Pull that little hose and see what's inside. Also the intake hose from there to the throttle body. Bet they are oily too. You may be able to rig up an oil separator into the little hose or even a breather filter of some sort to make the cleaning last longer. A little oil in vapor form will go a long way, that's why it's not low on the dipstick.
 

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Discussion Starter #3
I will do that. I will be looking at it again on Sunday. Also, low compression is a possibility. It had a cracked air filter lid when she got it. The intake tube was filthy. I don't know how long it was cracked, maybe years.
 

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OH NO, it scratched the hell out of the rings and cylinder walls. It's just spewing combustion pressure and gasses into the crank case and pushing it into your intake. Not much you can do about it. Don't drive it far from home. Good luck.
 

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Discussion Starter #5
She and her boyfriend live in the city. It does about 25 miles daily, 7 days a week. It comes to my house out in BFE about 35 miles one way every few months. Someone told them it was a sensor. She is not sure what "sensor" the guy was referring to. I can't think of any that would make an engine behave the way it does. I'm not going to just throw sensors at it and hope some random so called professional mechanic was right.
 

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Sounds like your codes are related to cam position correlation faults. This is fairly common on the 2.2 VVT and 2.4 VVT engine. Essentially the chain has stretched and the VVT solenoids are noticing the intake and exhaust cams aren’t lining up at the correct timing marks due to the timing chain slack. This is causing the engine idle issues and random stalling. This engine is probably in need of a rebuild. More than likely it didn’t receive proper oil change intervals which contributed to the excessive wear. It’s also very possible this engine ingested dirt since the air intake lid was cracked and the tubing is dirty. Long story short, without knowing the service history of the vehicle we can’t say for certain if it was the cracked air box or the poor routine maintenance practices that causes your issue. For S&G you should do a compression test to see what you’re dealing with. Good luck.
 

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Discussion Starter #7
Compression test PSI
DRY
CYL 1=122, 2=135, 3=117,4=150
WET
CYL 1=145, 2=140, 3=130, 4=155
The car lopes at idle like a vacuum leak. I've checked everything with carb cleaner, I've cleaned the TB with 3m Intake cleaner, I replace the coolant cap, and changed the oil again.
It still has codes PO 0010, PO 0011, PO 708. I've reset the codes with Torque Pro, only to have them reappear with a trans range circuit code, and a TC lockup code.
 

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Sorry to hear. That engine is near the end of its life. The codes are related to the timing system. IMO it’s not worth replacing the timing chain system on an engine with those compression numbers.
 
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