So I was accelerating onto the highway and I lost a cylinder. I went to the dealer and they diagnosed a misfire. They wanted $1,350 to change the plugs and wires! I was blown away. I found a local place that would do it for $800 but I still thought it was too high.
So I ordered the parts online. I was told that the wires should be Bremi or Beru to ensure factory quality. I found those for $200. Then I was told the factory plug is a Bosch part# FR8DPP33. I also ordered these online for $4.71 each. I wanted to use the Bosch 2's but I was told not to. I am not sure how accurate that is but why take a chance. Could not find or order the plugs from Autozone or Advance Auto they both said they could not get them. So in total it cost me about $260 in parts incl S&H. WHAT A DIFFERENCE.
Here are some pointers as I just finished the project. Took me 2.5 hours.
+ First two steps: Make sure engine is COLD!
- Take off engine cover. Just pops off by lifting up from front
- Remove top of air filter box 6 clips on box and 2 clips on hose
+ ML320 is a 6 cylinder but it has TWO PLUGS PER CYLINDER
so you need 12 plugs and the ignition wire set comes with 12 wires.
+ Start the with passenger side much easier. Learning curve is fast and once you do 2 plugs and wires it will go faster. You DONT want to learn on the driver's side.
+ Wear gloves or your hands will get cut up. Especially on the drivers side from the heat shield
+ You DO NOT have to take off the coil packs on the passenger side as long as you have an extension long enough to get into the cylinder and clear the coil packs.
+ I found it easier to pull the wires off the coil packs with the coil packs STILL ATTACHED
to the engine block. You can get more leverage... use pliers. I actually found this to be the hardest part.
+ Tools needed: Pliers, Spark Plug tool 5/8" w/extension(s) 2.5" & 5", and Torx #T30, some WD-40 or plug grease will help the wires pop on easier. A flashlight will also help but not necc.
+ I found that having different size extensions small 2.5" and medium 5" was very helpful b/c the spaces to get the plugs are different on each cylinder due to hoses and other engine parts.
+ On the drivers side remove coil packs after popping off old wires and then connect all new wires.
+ You really dont need to do one at a time as I have read on other posts. You will notice that each coil pack is labeled A & B for each wire.... AS IS the cylinder. So really as long as you can read A & B you will know where each wire needs to go. I needed a flashlight to actually read the lettering. Without it I could not see A & B.
+ Out of the 12 wires 4 are longer. These are for the two cylinders closest to the windshield. 2 on driver side and 2 on passenger side. The other 8 wires are all the same length.
Good Luck... DIY and save $$$$$ for your toys!!