This is in regards to my 2002 Daewoo Lanos, 1.6L automatic, with approximately 91,000 miles.
This car has run poorly now for over a year, and now that I have more free time, I would like to do something about it–either fix it if it can be fixed, or else junk it and buy a different used car.
The problem is that the engine misfires a lot at idle, and the whole front end shakes violently, but once I get moving it seems to run ok. There is no visible smoke, no noticeable oil consumption, and the performance seems adequate for this type of car. It also requires several attempts to start once the engine is turned off for more than 10-15 minutes.
Thus far, I have already replaced the fuel pump (due to an inoperable fuel gauge, which the new fuel pump solved), fuel pressure regulator, and all 4 fuel injectors (due to one injector leaking a lot, and one leaking a little). None of those steps solved the engine performance issues, and of course I also replaced the spark plugs and ignition wires, etc.
Back in June, I took the car to a professional mechanic, which my employer uses, and he determined that there is an internal problem with the engine, and as a result, the spark plug for cylinder #3 gets oil on the tip, which causes a misfire. He also determined that two cylinders had approximately 130 psi of compression and two had approximately 150 psi, but the only published specification is that 100 psi is the “service limit” for this engine. He said that if I wanted this diagnosed further, I could take it to another shop, which one of his friends owns, and they could determine if the engine is repairable.
I am considering now whether it makes more sense to have this engine fully diagnosed…was quoted about $350 to do this, or if it makes more sense to assume the problem is top-end and that a DIY cylinder head replacement will make this engine run properly. I can get a remanufactured head plus the additional materials needed to do the job for about $650 including tax and shipping. I would also need to purchase a professional torque-angle tool, about $600, but once purchased, I assume this tool will last for the rest of my life since I’m just a DIYer.
Supposedly, this engine is identical to the 1.6L E-TEC used in the 2004-2008 Chevrolet Aveo, with the only difference being the porting on the head (Lanos uses an aluminum intake manifold, and Aveo uses a plastic intake manifold, and they don’t line up exactly). So I have read information online regarding engine problems with the 2004-2008 Chevrolet Aveo, and found that valve guide and valve stem seal problems are a known issue, and that a small number of people have reported problems with oil control rings.
Based upon this information, does it make sense to spend $650 on materials and $600 on a specialty tool to replace the cylinder head, without further diagnosis, to spend $350 on further diagnosis, or to just buy a different used car now? The car is in excellent condition, with no rust or body damage, and I am happy with it, except for the engine problem.