I have a 97 Sunfire se 2.2l 5 speed that has been giving me a lot of trouble lately. A few weeks ago it started to have a slight misfire on occasion at highways speeds. Ran some injector cleaner through it with a full tank of gas from BP and it didn't seem to help. Check engine light was on so i got out my scan tool and got a slew of codes. Started out as TPS, o2 bank 1, cam position sensor and crank position sensor.
I started out by replacing the TPS and o2 sensor, cleared the codes and it ran great for a couple of days. The misfire came back but started getting worse, car idle's rough, loss of power and won't stay up to speed, will clear up and run fine for a few miles then start to misfire again.
Scanned for codes again and only got p1133 o2s1 switching insufficient. Started checking around online, many places said an exhaust leak can cause this. I brought it home, put it up on jack stands and noticed almost all the exhaust was ready to fall apart. I fixed the exhaust today and took it for a test drive, car ran great for about 35 miles then started misfiring again and code p1133 is back.
At this point i have Replaced : All of the exhaust from the manifold back including cat, muffler, and manifold gaskets. Both o2 sensors, spark plugs gapped at .050. Coolant temp sensor (fan wasn't working)
Not sure where to go from here, going to exchange the bank 1 o2 sensor for another in case i got a bad one and go from there.
Any help is greatly appreciated.
