2007 Saturn Ion Q&A

2007 Saturn Ion Question: Check engine light illuminates

The check engine light of my 2007 Saturn Ion 3 illuminates constantly. I took it to a repair shop and the owner told me that the 3rd cylinder is misfiring. However, no one could figure out the cause of the problem I took my car to a friend's house, and he used a code reader to extract the trouble code from the computer. I don't know what the code was, but he confirmed a misfire in the 3rd cylinder. The car seems to run fine, but the check engine light stays on. What could the problem be? -
Answer 1
well, you need compression, spark and fuel to make the cylinder work. all these things need to be checked. Roy -
Comment 1
what about oxygen? -
Comment 2
I took my car to another mechanic, and he performed a compression check on all 4 cylinders. He discovered that the compression was relatively low in the 3rd cylinder compared to the others. He believes there is a problem in the valves. I hope he is right, because a valve job is pretty expensive. -
Answer 2
A professional grade scan tool will give misfire count per cylinder, and air/fuel ratio fuel trim figures to show if a cylinder is "lean", as Roy said, check compression see its even, look for vacuum leaks at manifold, mis-fires can be hard to trace without training or very good scan tool. -
Comment 1
I took my car to another mechanic, and he performed a compression check on all 4 cylinders. He discovered that the compression was relatively low in the 3rd cylinder compared to the others. He believes there is a problem in the valves. I hope he is right, because a valve job is pretty expensive. -
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