Our 2000 ML320 (106K Miles) has recently been experiencing a rough idle (smooths out when placed back in Neutral or Park). The other day the Check Engine Light came on and it started running real bad at higher RPMs. The code was P0305 (#5 misfire) I had my wife limp it home I knew that it had the original Bosch plugs in it so went out and bought NGK 7090 plugs. What a joy to change those things! A hint. Do the driver side first. It is the hardest side, but very possible. Make sure that you put a piece of tape across the screw hole on the coil packs to hold the screw in place as you lift them off. It's also a good place to mark what cylinder it goes on. The passenger side only takes about 1/2 hour after fighting with the driver's side. Cleared the code with a reader.
I stated it up, the idle was better, but not smooth. Let it warm up and increased the RPMs. The CEL came back on. I checked codes and the same one came up. Swapped coil packs between #4 and #5. Misfire code moved to #4 confirming defective coil.
I went to the stealership and contributed $311 to their slush fun for 1 new coil and 2 plug wires. Most of the plug wires had been replaced during warranty for various other issues so I though new wires could not hurt since #5 still had old wires. FYI those wires are $60 EACH!.
Installed everything, crossed my fingers and started it up. Success! Gone is the stumble when accelerating, rough idle and CEL. For a grand total of about $360 I now have new plugs and a running car. I've seen posts about $750-1000 spark plug changes at the dealer. Who knows what my repairs would have cost with diagnosis and other charges at the dealer. All I lost was the experience of sitting there for about six hours and perhaps the usual car wash (with the smeared windshield).
This forum has saved me so much money and taught me so much about our ML. You all deserve a pat on the back for your contributions and generous sharing of information. Thank you.
I stated it up, the idle was better, but not smooth. Let it warm up and increased the RPMs. The CEL came back on. I checked codes and the same one came up. Swapped coil packs between #4 and #5. Misfire code moved to #4 confirming defective coil.
I went to the stealership and contributed $311 to their slush fun for 1 new coil and 2 plug wires. Most of the plug wires had been replaced during warranty for various other issues so I though new wires could not hurt since #5 still had old wires. FYI those wires are $60 EACH!.
Installed everything, crossed my fingers and started it up. Success! Gone is the stumble when accelerating, rough idle and CEL. For a grand total of about $360 I now have new plugs and a running car. I've seen posts about $750-1000 spark plug changes at the dealer. Who knows what my repairs would have cost with diagnosis and other charges at the dealer. All I lost was the experience of sitting there for about six hours and perhaps the usual car wash (with the smeared windshield).
This forum has saved me so much money and taught me so much about our ML. You all deserve a pat on the back for your contributions and generous sharing of information. Thank you.
