If your Infiniti Qx4 is misfiring or sputtering, chances are you need to change the spark plugs. Spark plugs receive an electrical charge from the distributor to complete the combustion process. If it is not able to do its part, then it misfires -- that is where the hesitation comes from when you accelerate. It will take about an hour to change all of the plugs in the Qx4.
Disconnect the negative battery cable using a wrench to loosen the terminal nut. Open the new spark plugs and check the gap between the filament and firing point using the feeler gauge. Spark plugs for the Infiniti Qx4 must be .40 hundredths. A feeler gauge measures this gap. It is usually factory set, but check them regardless. Insert the .40 hundredths blade into the gap and pull it through. You should feel some drag as you pull the blade through.
Remove one of the spark plug wires by grasping the boot firmly close to the engine and pulling it off. Do not pull it off by the wire or you will damage it. Remove the spark plug using the Infiniti spark plug tool and discard it.
Put the new spark plug into the cylinder head and tighten it with the spark plug tool. Push the spark plug wire back onto the plug until it snaps into place. Repeat the process on the remaining spark plugs.
