I have an 07 Cobalt LS 2.4 that just hit 100k miles. It runs alright for the most part, but recently, I've had what appears to be a serious loss of engine power.
I can easily rev the engine up to 5k+ RPM but it just doesn't accelerate at more than a snails pace. It's also been idling very rough, with this rhythmic rocking back while idling, and has a slight power knock. I've also been having trouble starting it. The engine cranks fine, and sounds good, but just doesn't always start right away. After 1-4 tries, it stumbles and stalls for a second, then finally manages to stay running.
I took it to the dealer, and after 2 days, the tech there literally told me he didn't know what was wrong with it, and that he recommended an engine swap. Judging by the fact that not so much as a speck of dust was shifted in under the hood, I don't think he did anything besides check the codes and charge me $100. (thanks New GM)
I've also done some work myself which I'll list here:
Replaced air filter and cleaned the throttle body.
Replaced the spark plugs. (plugs had some corrosion but no fouling)
Changed the oil. (no leaking of oil into coolant or coolant into oil btw)
Coolant itself is fine, and so are temps. Stable in the ~200f range.
The tech claims to have checked the transmission and said it was fine, and it doesn't seem to have any trouble shifting.
Far as codes go, I don't have the list with me at the moment. I checked it before I took it to the dealer, and it was quite long. 19 of them IIRC. The tech said he fixed some of them that were under warranty/recall, so I need to check it again.
Off the top of my head, all I remember is a bunch of air related codes, such as the MAF and MAP sensors, and a knock code on one cylinder. I'll post the full list as soon as I get it checked again.
I can easily rev the engine up to 5k+ RPM but it just doesn't accelerate at more than a snails pace. It's also been idling very rough, with this rhythmic rocking back while idling, and has a slight power knock. I've also been having trouble starting it. The engine cranks fine, and sounds good, but just doesn't always start right away. After 1-4 tries, it stumbles and stalls for a second, then finally manages to stay running.
I took it to the dealer, and after 2 days, the tech there literally told me he didn't know what was wrong with it, and that he recommended an engine swap. Judging by the fact that not so much as a speck of dust was shifted in under the hood, I don't think he did anything besides check the codes and charge me $100. (thanks New GM)
I've also done some work myself which I'll list here:
Replaced air filter and cleaned the throttle body.
Replaced the spark plugs. (plugs had some corrosion but no fouling)
Changed the oil. (no leaking of oil into coolant or coolant into oil btw)
Coolant itself is fine, and so are temps. Stable in the ~200f range.
The tech claims to have checked the transmission and said it was fine, and it doesn't seem to have any trouble shifting.
Far as codes go, I don't have the list with me at the moment. I checked it before I took it to the dealer, and it was quite long. 19 of them IIRC. The tech said he fixed some of them that were under warranty/recall, so I need to check it again.
Off the top of my head, all I remember is a bunch of air related codes, such as the MAF and MAP sensors, and a knock code on one cylinder. I'll post the full list as soon as I get it checked again.
