My 2005 S-type V-8 with about 90K miles occasionally mis-fires on start-up, especially when warm. Codes for 1 3 5 7. Thoughts, pls?

 

Hi hocojimjag,

All of your misfires are in Bank 1, the right bank of cylinders as viewed from the driver's seat. A couple of possibilities come to mind:

1. Leaking spark plug tube seals on the Bank 1 camshaft cover, allowing oil to spill into the spark plug tubes, which interrupts the spark plug ground path through the cylinder head and causes misfires. You can check for this by pulling a couple of the ignition coils and looking down into the spark plug tubes for oil. The solution is to replace the cam cover gasket and spark plug tube seals.

2. An air leak at the PCV valve/vent or its associated plumbing can cause lean running and misfires in only Bank 1, but you will usually also have a lean code for Bank 1 (P0171). The PCV vent is the flat, black circular component mounted near the front end of the Bank 1 cam cover. Often, you can hear the sound of air hissing near the vent, and by (carefully) manipulating the vent and the plastic hose attached to it you may hear a change in the hissing sound, confirming the leak(s).

Cheers,

Don