Misfire Code
Thread Starter
Member
Joined: Feb 2013
Posts: 152
Likes: 2
From: San Diego, CA
99 E55, 00 S500, 01 CLK55, 01 E320, 04 E320
Misfire Code
Hey guys,
I have 2011 GL450, around 150K miles.
Car drives fine but I started getting cylinder 5 misfire. Engine light would come on and stay few days and go away. I replaced spark plugs, and swapped coils. But Cylinder 5 misfire would come back. Few month prior plastic manifold arm broke and I got it replaced with metal URO part. Cylinder 5 misfire got back. I replaced injector and cylinder 5 misfire got back again. Again, car drives fine.
My mechanic says manifold is probably toast. I dont want to jump on this expensive repair before asking you guys. Any ideas why cylinder 5 misfires even after, spark plug, coil and injector change?
PS: P0171 started to pop up as well.
Thanks!
I have 2011 GL450, around 150K miles.
Car drives fine but I started getting cylinder 5 misfire. Engine light would come on and stay few days and go away. I replaced spark plugs, and swapped coils. But Cylinder 5 misfire would come back. Few month prior plastic manifold arm broke and I got it replaced with metal URO part. Cylinder 5 misfire got back. I replaced injector and cylinder 5 misfire got back again. Again, car drives fine.
My mechanic says manifold is probably toast. I dont want to jump on this expensive repair before asking you guys. Any ideas why cylinder 5 misfires even after, spark plug, coil and injector change?
PS: P0171 started to pop up as well.
Thanks!
Last edited by noud; Mar 19, 2026 at 09:40 PM.
Member
Joined: Apr 2011
Posts: 167
Likes: 60
From: Denver
2005 ML500, 2011 E350 4M, 2012 GL550
For the #5 misfire;
Coils are changed but they are good for sure? Tried to swap em and test again?
Injector gets correct voltage? Bad ground?
Did you get a chance to test the compression for that cylinder?
For P171
MAF sensor is good, clean?
Fuel pump is putting out enough pressure?
All the vacuum hoses are good, any cracks, leaks?
Coils are changed but they are good for sure? Tried to swap em and test again?
Injector gets correct voltage? Bad ground?
Did you get a chance to test the compression for that cylinder?
For P171
MAF sensor is good, clean?
Fuel pump is putting out enough pressure?
All the vacuum hoses are good, any cracks, leaks?
Thread Starter
Member
Joined: Feb 2013
Posts: 152
Likes: 2
From: San Diego, CA
99 E55, 00 S500, 01 CLK55, 01 E320, 04 E320
For the #5 misfire;
Coils are changed but they are good for sure? Tried to swap em and test again?
Injector gets correct voltage? Bad ground?
Did you get a chance to test the compression for that cylinder?
For P171
MAF sensor is good, clean?
Fuel pump is putting out enough pressure?
All the vacuum hoses are good, any cracks, leaks?
Coils are changed but they are good for sure? Tried to swap em and test again?
Injector gets correct voltage? Bad ground?
Did you get a chance to test the compression for that cylinder?
For P171
MAF sensor is good, clean?
Fuel pump is putting out enough pressure?
All the vacuum hoses are good, any cracks, leaks?
Senior Member
Joined: Aug 2018
Posts: 405
Likes: 121
From: Kelowna, BC
08 GL320 CDI
When its running physically grab the wires going to the coil and injector for number 5 and wiggle them around, maybe you have a broken wire internally or a connector not seating fully??
