S-Class (W140) 1991-1999: 300 SD, S 350TD, 300 SE 2.8, S280, 300 SE 3.2, 300 SEL 3.2, S320, S320L, 400 SE, S420, 400 SEL, S420L, 500 SE, S500, 500 SEL, S500L, 600 SE, S600, 600 SEL, S600L, 500 SEC, 600 SEC

1995 S420 misfire - looking for coil replacement DIY

Thread Tools
 
Search this Thread
 
Rate Thread
 
Old 09-19-2010, 02:26 AM
  #1  
Newbie
Thread Starter
 
last993's Avatar
 
Join Date: Jul 2008
Posts: 9
Likes: 0
Received 0 Likes on 0 Posts
03 ML500
1995 S420 misfire - looking for coil replacement DIY

Please, help.

95 s420 w/ 65,000 miles
Engine sputters idle, bad exhaust rotten egg smell
Did spark plus, rotors/distributors 5,000 miles ago
Suspect coil gone bad, where is it located at ?..did search w/ no luck

Your help/input would be much appreciated !
Old 09-19-2010, 12:15 PM
  #2  
Member
 
deanyel's Avatar
 
Join Date: Jul 2006
Location: Phoenix, AZ
Posts: 100
Likes: 0
Received 0 Likes on 0 Posts
400E
There's two coils, one for each distributor cap. They are down by the ABS pump, front/left of the engine compartment. Follow the coil wires from the distributor caps. But it's quite unlikely that you have a coil failure at that mileage, or double that mileage. Better to start by reading the fault codes on the 38 pin connector in the engine compartment.
Old 09-19-2010, 03:43 PM
  #3  
Newbie
Thread Starter
 
last993's Avatar
 
Join Date: Jul 2008
Posts: 9
Likes: 0
Received 0 Likes on 0 Posts
03 ML500
Thank you very much for the prompt reply, I found both of them this morning, one of them appears to be located in a place almost impossible to get to w/o removing the headlight assembly

I unplugged each one from the distributor cap, then made an attempt to start the engine.
I managed to start the engine w/ only one plugged-in. It ran smoother w/ no power. I suspect the one that's gone bad is the one I couldn't start the engine w/ ?...it's the one located in a very hard place to access

Am I on the right path ?

Am I
Old 09-19-2010, 11:13 PM
  #4  
Member
 
deanyel's Avatar
 
Join Date: Jul 2006
Location: Phoenix, AZ
Posts: 100
Likes: 0
Received 0 Likes on 0 Posts
400E
Hard to say for sure. Could be a problem with a spark plug wire or two, or one of the coil wires. You can interchange the coils if you wish - they are the same except for the mounting schemes. I'd still start with the fault codes. Your car has one of the all time great DIY fault code reading systems. Can you just remove the back cover of the headlight?
Old 09-21-2010, 11:12 PM
  #5  
Newbie
Thread Starter
 
last993's Avatar
 
Join Date: Jul 2008
Posts: 9
Likes: 0
Received 0 Likes on 0 Posts
03 ML500
Thank you, I will try to pull out the code over this weekend

Currently Active Users Viewing This Thread: 1 (0 members and 1 guests)
 


You have already rated this thread Rating: Thread Rating: 0 votes,  average.

Quick Reply: 1995 S420 misfire - looking for coil replacement DIY



All times are GMT -4. The time now is 06:54 PM.