I recently purchased a 2006 S2K. I had it delivered to my house and upon receiving the car I took it to the gas station and filled it up with 91 octane. About 5 miles after filling it up on an empty tank my CEL came on. I took it to Auto Zone and discovered that I have a Misfire Detected in Cylinder 1. Since then I have changed the spark plugs, cleaned the injectors, and swapped the coil packs. Still no luck as the CEL continues to come on. After I reset it I drive for quite awhile before the CEL comes back on. If I took it to a dealership could they quickly diagnose the cause or would they be playing the same guessing game that I am. My next step is to replace the injectors and then move on to valve replacement. Any thoughts???

 

Check the O2 connection.

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Could an O2 Sensor trigger a misfire in a single cylinder repeatedly? Seems like a the sensor would trigger multiple or random misfires.

 

Have you run through the gas you put in?

Also, has a valve adjustment ever been done on the car? 06+ are prone to tight exhaust valves and tight clearances will cause a misfire.

 

I have just finished off the first tank... That was another thought I had. It's possible that the previous owner never used gas over 87 octane. I'm thinking that my switching to 91 octane may trigger a Cylinder misfire, but again it is still strange that it is only one cylinder. I just purchased the car so I'm not sure that a valve adjustment has ever been done. The car has only had one owner and has low mileage, but is not in the best of shape so I'm thinking the previous owner didn't baby the car as I do.

 

Check the valve adjustment.

Would you consider replacing the valves before adjusting the ones you've already got?

 

I would prefer to adjust the valves rather than replace the valves if it isn't necessary. Where is the best place to purchase parts?

 

If you haven't already tried I would swap injectors between cylinders to see if the misfire follows the injectors. Also they may be too new but check the condition of spark plug 1 compared to the others to see if it is being fouled by oil or fuel.

 

I used to get a misfire on cylinder 4 on and off every few months. During a valve adjustment recently we found the only one that was too tight was cylinder 4. We are almost certain that was the reason for the misfire.

 

Last year I had misfires on all 4. Changed my plugs and all was good. The CEL is back again since winter storage. I remember reading it could possibly be a drop in voltage in the alternator causing the misfires.