A 2-pole wire will not work on a 3-pole plug. You will need to use a 3-pole wire on a 3-pole plug.
The earth wire.
The term "double pole" usually means a breaker with 2 handles that attaches in the space as a normal single pole breaker. If this is what you mean, no, you cannot. There is no potential, or voltage, between the wire terminals. If by "double pole" you mean what is usually called a 2-pole breaker, which is a breaker with 2 handles that attaches in the space of 2 single pole breakers, then yes, you can use this breaker and 12/2 wire to produce a 220v circuit.
2 pole, 3 wire.
the black wire is the hot wire
On a 3 wire plug (NEMA 5 configuration, 125v 2 pole 3 wire grounding) the narrow blade is the "hot" lead, the wide blade is the neutral lead, and the U shaped prong is the equipment grounding conductor (EGC). Most 2+G non-metallic-cables (NMC) are color coded for Black = "hot", White = neutral, and Bare = EGC
In a 6-30 3 prong female plug, there are two hot wires, which are usually black or red, and these connect to the two hot terminals. The neutral wire, typically white, connects to the neutral terminal, and the green wire, which is the ground wire, connects to the ground terminal.
can a 20 amp double pole circuit breaker be used for 2 different 120 v circuits using 14 - 2 wire
1) because spark plugs work by getting a huge blast of electricity delivered to them through the wire 2) because the insulation of the wire isn't perfect, so part of that electricity can jump to you.
If you have a no fire situation on #2 cylinder, then the plug is bad, or plug wire is bad, or coil is bad if it has a coil on plug configuration. You may also have a burnt valve, or blown head gasket.
2.5L Take a look at the distributor cap. It should have a "1" on it. That goes to the front of the engine. The rotor turns clockwise when looking at it from the front. The next wire is going to be 3. Plug that wire into the 3rd plug from the front. The next one is 2. Plug that wire into the 2nd plug. The final one is 4. Plug that into the furthest plug.
code P0302 would indicate a misfire in cylinder #2 .Most common thing is a plug or wire , But this could be a number of other things causing cly. #2 to misfire.
Change the wire, or coil plug