GM 2.2 Four Cylinder P0300

2005 Saturn Vue with the 2.2 Four clyinder (the newer GM Quad4). VERY rough running, about 1/2 power, exhaust smells, engine running hot/cooling fan running constantly. I have changed the plugs, wires/boots, and coil pack. Showing P0300 code. Is it the Catalytic converter or the 02 sensor? Looking for a quicker fix. Only vehicle.

The exhaust could be clogged or the timing chain has jumped. If you loosen the exhaust and crank it up.. if it runs better the cat is clogged.

Replaced the catalytic converter today 6/8/09 and both up/down stream O2 sensors. Yes, the cat blew it's guts down the pipe. Problem/code still exists. Old ignition coil pack is back in. With new sensors and cat converter, should I go back to the new ignition coil pack or WTF. The only other option I have (as far as I know) is the ignition control module for about another $100. I have run out of patience, time, and getting close on money.

Did u check the convertor before you replaced it? I have done some timing chains on these they jump and make no noise. So you need to find out if it is fuel, ignition, or mechincal. If the convetor was melted it is probably the result of this problem and will do it again unless fixed.

Yeah it's an ecotec is it not? They're normally a pretty stout and relaible engine. I'd get it diagnosed at this point. If it's running that bad then the fuel trims and data should show someone enough info to diag it correctly. Im skeptical on the ignition module unless you've got carbon tracks on the plugs from boots or coils within it that are causing some cyls to misfire,. With a good scanner you should be able to watch the misfire monitor to see which cylinder is misfirng the most and address it. As well verify correct feul pressure etc.

I have replaced the plugs, wires, ignition coil pack, cat converter, and both up/down stream O2 sensors. I have an ignition control module on order but am looking at the timing chain next. I have also heard that these are reliable engines in the Cobalt. I'm not sure if it makes a difference what platform this engine is put in but......... I have also been told that this is GM's updated version of the old Quad4 which I had in an 88 Grand AM. Same issue but I never saw that one all the way through. I guess I'll just check the chain on my 2005, 53000 mile engine. Thanks for everyones help.

P.S. Yes, it is a 2.2 Ecotec. Thanks again.

Light at the end of the tunnel I hope. My diamond shaped timing mark isn't lined up w/ my copper link so it looks like it did jump. I have to adjust the chain now correct?

Adjust? if it went out of time I'd think the tensioner is no good and or the chain has stretched.

Don't get to excited...The gold links will not line up with the mark on the gear once the engine has been turn over..

Yeah, I talked to some other folks abouth the colored links and found out that that was the case. I now have a ignition control module on order and I have heard that that works. Thanks guys.