Just picked up a 2008 Aveo LS as a beater, and have begun some maintenance on it. I will explain the rough idle, but here is what's been going on so far:
- Initial CEL popped, showed codes for random misfire. I replaced the valve cover gasket, and all spark plugs.
- Idle remained rough, CEL cleared and no more misfire or oil on spark plug #1. Changed oil, filter, and oil pressure switch.
- On a quarter tank of gas, I dumped 3oz of seafoam into the crankcase, and 3oz of Lucas Oil injector cleaner/upper cylinder lubricant.
Car is running better, BUT I still have a rough idle. I do not hear a vacuum leak, but I cannot rule this out. Vehicle has 164k, is a 5M/T, have dealer receipts from previous owner. Dealership replaced fuel injectors, checked fuel pump (did not replace), replaced timing belt and components, as well as exhaust from the resonator back.
I do not know if timing was done properly, it's possible the tooth is off by 1. If anyone has had similar issues, I'd love to hear from you. In the meantime I'll be digging through the forums.
Please forgive me for any formatting ugliness, I'm on mobile.