Post by bobsblue95 on Mar 16, 2012 12:09:28 GMT -6
I've had a somewhat intermittent miss at idle for a while. New plugs and wires etc... basically I've suspected it's a failing coil for a while, but can't afford to buy four new ones. Today I tracked it down by simply examining my spark plugs. (95 doesn't tell you which cylinder(s) is/are misfiring.)
Pull the front plugs and look at the tips. They should be a nice light tan color. Three of mine were ash-white, indicating a lean cylinder. One (#6) was almost black, indicating a rich cylinder. Can you guess which coil was failing? If you're so inclined, pull the back plugs to verify that the other plug on the same coil shows the same condition.
I replaced the coil and my idle is rock steady now.
What happens is the missing or weak spark causes the fuel not to burn well, resulting in rich exhaust. The PCM sees this and compensates by leaning it out, which affects the good cylinders. Reading your spark plugs is always a good place to start when diagnosing engine troubles.
Hope this helps someone.
Pull the front plugs and look at the tips. They should be a nice light tan color. Three of mine were ash-white, indicating a lean cylinder. One (#6) was almost black, indicating a rich cylinder. Can you guess which coil was failing? If you're so inclined, pull the back plugs to verify that the other plug on the same coil shows the same condition.
I replaced the coil and my idle is rock steady now.
What happens is the missing or weak spark causes the fuel not to burn well, resulting in rich exhaust. The PCM sees this and compensates by leaning it out, which affects the good cylinders. Reading your spark plugs is always a good place to start when diagnosing engine troubles.
Hope this helps someone.
