Bad 02 sensor cause misfires?

**dowsett6** · 12-15-2009 06:09 PM

Hey everyone,

My exhaust turbine decided to eat my wastegate flap so I swapped out the turbo with another one. The one that went into the car leaks oil as I am now burning oil where as before I wasn't.

Since swapping the turbos I now have a misfiring issue that only happens when under load (in boost). The engine does seem to stutter a bit in low vacuum though.

I am getting CEL for the misfires. Codes: p0300, p0301, p0302. (Multiple misfires, cyl 1 misfire, cyl 2 misfire)

I have checked almost everything I can think of that would cause misfires and the issue is still here. So now I am wondering if the oil burning issue might have fouled my O2 sensor and if a bad O2 sensor would cause misfires.

Thanks in advance.

**dowsett6** · 12-15-2009 06:19 PM

pics for clicks hopefully. Thats the exhaust turbine the wastegate flap jumped into.

**walky_talky20** · 12-15-2009 06:46 PM

Well, I'm sure a little oil into the exhaust isn't doing the O2 sensors any favors. I'm not sure if that small amount would cause misfires, but I can tell you my experience.

I had a K03 turbo failure (journal bearing failed) causing massive oil into the exhaust. It gradually went from "Gee, the exhaust is a little dark" to CLOUDS of black smoke billowing from the tailpipe and filling the cabin in the course of just a few miles. The car ran just fine until the smoke completely blackened. At that point the idle was very jumpy and the car had very little power. I don't think it misfired really, and I don't think the engine light flashed, but it did run poorly. I think the poor running was absolutely caused by the O2 sensors getting covered in oil. I think it was even worse as my '01 has a wideband sensor as primary.

I guess my point is that even enough oil burning to slightly darken the exhaust didn't cause misfires for me. Only when massive amounts of oil were burning was engine performance noticeably affected on the highway. Luckily my car only had to endure that for 2 miles or so while I limped it to a service station, and both O2 sensors were just fine after the new turbo. Although it is possible their life expectancy was shortened.