I can't locate the spark plugs on my 2002 toyta camry. It's a two wheel drive 4 cylinder.

Each spark plug has its own ignition pack, that is part of the spark plug connector that you pull out of the cylinder. You have 4 of them.

Down into the center of the valve cover, where the 4 wires are leading into.

When is the last time the engine was tuned and the injectors flushed using a special machine. No the kind of worthless stuff you pour in the tank.

First, remove the no. 1 engine cover. Locate the ignition coils, these will be squarish-looking packs with spark plug wires (4 of them) coming out. The wires should be going to the spark plugs, which are on the front and back side of the engine.
Grab the ignition coils or spark plug wires by the thick plastic piece at the end of the wire. Squeeze the end and turn it to release it from the spark plug. Pull back to remove the plug from the engine.
Slide the spark plug socket over the spark plug. The most common size of spark plug socket used on a Toyota Highlander is 16mm. Turn the socket to the left to unscrew and remove the spark plug from the cylinder well.

The spark plugs are located normally near the value cover where you put in the oil. The wires run from the spark plugs. If your vehicle is a 4 cylinder then there will be 4 spark plugs. If it's a 6 cylinder there will be 6 spark plugs.

It's according to how man cylinders in your engine. 4 with 4 cyl and 6 with 6 cyl

• Available engines
  • 4 Cylinders E 2.4L MFI DOHC
  • 6 Cylinders A 3.3L SFI DOHC (found in 37% of 2006 Toyota Camry)
  • 6 Cylinders F 3.0L SFI DOHC (found in 63% of 2006 Toyota Camry)

well the 4 spark plug is located in front on the cylinder head,you have to take out the wire of the spark plug the you can see it,note; when you take out the cap from the spark plugs put a marking on the cap to make sure you dont put the wire for the 1st cylinder to the 3rd cylinder .....

3.0L (2V) = 1-4-2-5-3-6

3.0L (4V) = 1-4-2-5-3-6

If 2 and 4 won't fire no matter what coil is there, then you likely have problems with either spark plugs or spark wires. If rotating the coil packs doesn't make a difference, it has to be something that's always "with" those cylinders, which would be plugs and/or wires. A new set of plugs is very inexpensive, and isn't a bad idea, especially if it's been awhile since they were changed. I'd try them, see if it works, and if it doesn't, try swapping spark wires between cylinders (at both ends - undo the wires from the coil AND plug and move them to another cylinder and see if the fault follows).

The solution is for a 4 cylinder
Find the camshaft cover, located at the top of the engine.
There yfind 4 square rubber objects with wires connected to the coils, pull them up, inside the exposed tubes you find the spark plugs.
You will need a 5/8 spark plug socket on an 8" extension with a ratchet to remove the spark plugs.

If you still get troubles, buy the repair manual here
Toyota Car Repair Manuals: Chilton & Haynes

There you can find detailed instrucions with pictures.