1993 Mercedes 300E - ignition coil or MAF sensor - Mercedes-Benz Forum

LinkBack Thread Tools Display Modes
post #1 of 6 (permalink) Old 05-13-2010, 08:14 AM Thread Starter
BenzWorld Junior Member
Date registered: May 2010
Posts: 7
Mentioned: 0 Post(s)
Quoted: 0 Post(s)
(Thread Starter)
1993 Mercedes 300E - ignition coil or MAF sensor

I have a 1993 Mercedes 300E with 150,000 miles that has failed Texas inspection. It shows safety passed but not emissions but there are no codes. I had one very nice german mechanic look at it and suspects it was the spark plug ignition coil but he had no diagnostic machine so he hated to spend the money and then that not be the problem. So, I went to another mechanic and he too felt it was the ignition coil and replaced with a used part. When I was on my 30 mile trip back home, it started doing the same thing. I took it back, he replaced with a new ignition coil but am having the same problem. I am going to bring it back for him to look at this weekend but really want some knowledge as to what is going on. I am a woman with little under the hood experience but I like to know what is going on and be an educated consumer. I was told to put Techron fuel (black bottle) in it and I will do that but not sure that is the overall repair needed. I am a teacher on a very tight budget so really need to do most economical fix. Here are the issues:

(1) When at a stop sign while in drive (automatic), after 30 seconds, the rpm's go down and it sounds and feels like it is going to stall (jerks a bit) and then on its own, the rpms will shoot up and it doesn't stall.
(2) After I start to accelerate after being stopped, it feels like little power is getting to the accelerator and takes a bit to gain speed.
(3) When I hard accelerate after being stopped, it will make a pop sound.
(4) There were no codes that came up on inspection. The inspector did mention it was unable to stay inside miles per hour when being tested.
(5) The one ignition coil that was showing to not be good has now been replaced and it seems a tad bit better while being stopped it still has same symptoms.
(5) The car drives great once you hit about 30 miles per hour.

I have researched and heard some mention of a Mass Airflow Sensor. Does my issues seem like that is a possibility? Can this be cleaned or does it have to be replaced? Could an air filter cause such an issue? My husband had mentioned a possible catalytic converter but I haven't seen much data on that as far as Mercedes goes. I appreciate your insight!
sjtcroland is offline  
Sponsored Links
post #2 of 6 (permalink) Old 05-13-2010, 09:38 AM
Outstanding Contributor
keyhole's Avatar
Date registered: Sep 2006
Vehicle: 2004 CLK 240 Coupe
Location: Norfolk. UK
Posts: 10,357
Mentioned: 9 Post(s)
Quoted: 343 Post(s)
Welcome - but you might have done better to have posted in the forum specific to your own model. That is the W124 forum, which will have many owners of similar cars and who know the symptoms of typical faults. 'General' is for topics about ALL models.

Well done for a good description of your problem, and I'm going to admit that I know little about MBs of your era. Somebody else will surely be able to give some relevant advice.

However, as a long-time car owner, and DIY fixer, I will take a punt and suggest that ignition problems generally occur across all engine rev ranges, not just the bottom end. On the other hand the MAF is affected by engine air intake, so it could be your problem. They do need changing from time to time. Some folks have managed to clean the sensor, but generally they are replaced. If this is done, take note of this entry I found in the WIS for your model.

"misfiring, bucking, or surging due to defective engine wiring harness in the area of the MAF" . "Usually no DTC stored"

So there is a known issue here, and if your MAF is changed, the associated wiring should be closely inspected.
keyhole is online now  
post #3 of 6 (permalink) Old 12-16-2010, 12:22 AM
BenzWorld Member
Date registered: Nov 2010
Vehicle: 1993 300E 2.8 (sold), 2012 C250 (wife's), 2004 C230 (sold), 2005 E320 (sister-in-law's)
Location: Cupertino, CA, USA
Posts: 257
Mentioned: 0 Post(s)
Quoted: 0 Post(s)
when you said "no DTC stored," what is DTC?? thanks!
ohman is offline  
post #4 of 6 (permalink) Old 12-16-2010, 05:59 AM
Outstanding Contributor
keyhole's Avatar
Date registered: Sep 2006
Vehicle: 2004 CLK 240 Coupe
Location: Norfolk. UK
Posts: 10,357
Mentioned: 9 Post(s)
Quoted: 343 Post(s)
Not sure exactly....but I have always assumed that it means Diagnostic Trouble Code. (or something very similar)
keyhole is online now  
post #5 of 6 (permalink) Old 12-16-2010, 06:45 AM
BenzWorld Elite
SHAUNE55's Avatar
Date registered: Aug 2010
Vehicle: 2001 E55 AMG
Posts: 3,294
Mentioned: 0 Post(s)
Quoted: 4 Post(s)
Whilst I agree with keyhole,I have had plenty of ignition problems that only occur at certain parts of the rev range.
SHAUNE55 is offline  
post #6 of 6 (permalink) Old 12-16-2010, 08:56 AM
Outstanding Contributor
keyhole's Avatar
Date registered: Sep 2006
Vehicle: 2004 CLK 240 Coupe
Location: Norfolk. UK
Posts: 10,357
Mentioned: 9 Post(s)
Quoted: 343 Post(s)
You are right of course.

I've now remembered the mis-firing issues that I had when I had a car with a distributor..... eg, it could be 'tracking' on a crack in the plastic cap.

Here are some suggestions for typical ignition problems from the WIS for W124 models.

Chapter: Programed Engine Repairs. Engine 103 Combustion IV KE Injection.
Attached Files
File Type: pdf W124 ignition.pdf (480.5 KB, 317 views)
keyhole is online now  
Sponsored Links

  Mercedes-Benz Forum > General Mercedes-Benz Forums > General Mercedes-Benz

Quick Reply

Register Now

In order to be able to post messages on the Mercedes-Benz Forum forums, you must first register.
Please enter your desired user name, your email address and other required details in the form below.

User Name:
Please enter a password for your user account. Note that passwords are case-sensitive.


Confirm Password:
Email Address
Please enter a valid email address for yourself.

Email Address:


  • Currently Active Users Viewing This Thread: 1 (0 members and 1 guests)
    Thread Tools
    Show Printable Version Show Printable Version
    Email this Page Email this Page
    Display Modes
    Linear Mode Linear Mode

    Similar Threads
    Topic Author Forum Replies Last Post
    Ignition key hard to turn on - 1993 300e Rick Dean W124 E,CE,D,TD Class 24 05-13-2010 12:26 PM
    Have narrowed it down to these 3 possible culprits... MAF, OVP, or Ignition Coil soundquest W124 E,CE,D,TD Class 10 03-23-2010 09:44 AM
    1993 300e oil sensor? randman Audio & Telematics Forum 0 03-23-2010 09:29 AM
    1993 300e 3.2 ignition problem 2xxturbo W124 E,CE,D,TD Class 7 03-29-2009 11:29 AM
    replacing an ignition coil for cyl #2 and cool temp. sensor, can i DIY? DnBtekhnic W203 C-Class 9 02-28-2009 10:09 AM

    Posting Rules  
    You may post new threads
    You may post replies
    You may not post attachments
    You may not edit your posts

    BB code is On
    Smilies are On
    [IMG] code is On
    HTML code is Off
    Trackbacks are On
    Pingbacks are On
    Refbacks are On


    Title goes here

    video goes here
    description goes here. Read Full Story
    For the best viewing experience please update your browser to Google Chrome