I have 2005 ford explorer 4.0L with about 240,000 miles. I was wondering if there's a way to know if its my coil pack or my spark plugs. Dont have much money so I want to hopefully make sure I'm fixing the right thing.
what seems to be the problem?
That voice to text Scotty uses sure results in some funny posts. I think Wells Fargo is about 35 bucks a share right now. {black}:sweaty:
Wells Fargo's are extremely cheap try them first
Spark plugs ARE relatively cheap, coil packs not so much. I think that was what Scotty was talking about.
If you don't have much money for parts or tools then there's a way you can still try to narrow down the culprit.
First, the misfire codes can be a clue.
Your coil pack is a "wasted spark" ignition system and each of the 3 coils in it is shared by 2 cylinders.
So if you have misfires on both cylinders 1 and 5, or both cylinders 2 and 6, or both cylinders 3 and 4, that would be a clue that one of the coils in your coil pack is defective.
You didn't mention them as a suspect but you could have a defective spark plug wire that's arcing to ground on something.
So get yourself a spray bottle of water and wait until the light is low (around sunset) and while your Explorer is running spray the entire length of each spark plug wire from the coil to the spark plug and look for arcing between the wires and any engine metal parts. At low light the "light show" will be easier to see.
Getting back to the coil pack, while the engine is running, (wear some gloves) remove each plug wire, 1 by 1, from the coil pack and slowly lift it above its coil tower. The spark should jump above the tower to the end of the wire.
If you lift one above its tower and the spark instead arcs inside the socket instead of jumping up to the plug wire, there's likely a defective/shorted coil. (electricity is lazy)
As far as the spark plugs, all 6 didn't fail at once so if you swap a spark plug from a "misfiring" cylinder with a plug from a good cylinder and the misfire moves to that "good" cylinder, and the "misfiring" cylinder now works fine, .... well, there you go.
Now these tests aren't going to be as conclusive as you'd get by testing the coil pack and wires with a $7 Harbor Freight multimeter and a $10 ignition spark tester, but just because you don't have them doesn't mean you have to blindly throw parts at the truck.
