W124 misfires after oil change - PeachParts Mercedes-Benz Forum

sjsfiji · #1 01-07-2003, 12:52 PM

Hi All,

I did my first oil change on my W124 last week. Accessed the filter by removing and reinstalling the air filter. I pulled one spark plug cable and reinstalled just so I can see how it sits. It's the one furthest front. I starterd her up and drove her a few miles and all was well. A few days later, I started her up and seems to misfire... i.e. real rough idling. Any suggestions?

thanks in advance...

sjsfiji

suginami · #2 01-07-2003, 12:55 PM

When you reattached the spark plug wire, the connection between the resistor boot and the wire probably became loose, or the wire is not firmly attached to the plug.

95E320cab · #3 01-07-2003, 12:56 PM

Maybe resistor ends going bad, plug wire, coil.

Mike Murrell · #4 01-07-2003, 09:50 PM

MB makes a special tool(pliers) for removing the resistor tips from the spark plugs on a 103 motor(your car).

I'm not saying that you must use one of these gadgets, but they simplify that task. The ceramic inside is easily damaged and that can cause rough idling/misfire.

If you're lucky, you might try to reseat the resistor. If it's damaged, you can replace the resistor tip vs. the entire wire as you may be accustomed to with domestic/asian models.

It screws on and off fairly easily. The pliers are available at:

http://www.************************

If you are going to perform basic maint. on your car, there are about $50 worth of special tools that will come in handy. They are outlined in the catalog available at the web site above.

sjsfiji · #5 01-08-2003, 08:56 PM

Hi All,

Thanks very much for your replies. They are much appreciated. I have yet to start her again and begin diagnosing the problem.

sjsfiji · #6 01-13-2003, 12:47 PM

I replaced all my spark plugs and it appears that the problem persists. Can anyone tell me or show me where I can find instructions on replacing the resistor tip on the spark plug wire. I'd had to buy a new set as they are pricy.

thanks,

sjsfiji

95E320cab · #7 01-13-2003, 01:00 PM

I sent you an e-mail nefore reading your post. Make sure the plugs you used did not have an "R" in the plug number. Stands for resistor. Too much resistance with the resistor ends. Caused idle problems with my car.

sjsfiji · #8 01-13-2003, 01:43 PM

I'm quite sure (99%) that it's not the new plugs. The problem arose after I pulled the wire a week or so ago. I just replaced the plugs a few days ago with exactly the same type/brand that was in there. Can someone point me to instructions on how to repair broken/damaged resistor tips. I'm thinking I damaged one or more since I didn't have the proper tool for pulling them off. Where can I buy this tool?

thanks,