P0300 Saturn -

Question

This is on a 2004 Saturn vue with the 2.2L. I have replaced all plugs with new ones last month, when we purchased it. We were told by the previous owner the exhaust manifold was cracked. It was replaced. For a month, nothing happened. Then I kept getting running rich on bank one. Could not diagnose the issue. Now today, it had a misfire on cylinder 3. I swapped out cylinder 3 with cylinder 2 plug. Now I'm getting random misfire code and she idles rough. Is the exhaust system restricted? Could you suggest a course of action? Thank you.

Answer 1

P0300 Random misifre

With a cracked exhaust manifold, the 02 sensor would see the engine as a lean condition and cause the engine to run rich. , If the exhaust was resitriced you would have no power going up hill, or acceleration. you would not have a misifre on one one cylinder at all, it would even code a P0420. When the coil shorts internally it can seem like a plugged exhuast