1988 420sel misfiring
 

Hello everyone,
I have a 420sel that is missing and I can't seem to put my finger on it. I tried to search the archives and came up with nothing, so if this is a repost I apologize.

What is happening: At low RPM the engine has a shudder at intervals. I've changed the spark plugs (used copper plugs) and it's still there. It is more pronounced when it is colder out, therefore I believe it's electrical. I was thinking perhaps the wires need changed? I'd like to check the resistance of the wires and the plug connectors, does anyone know what these should be?

Anyway, the shudder comes and goes, and after driving at highway speeds the shudder isn't nearly as bad.

Thanks in advance!

Check all the components involved with the fuel delivery. Especially the fuel distributor and injectors.

Ok I'll try that. I've been running premium unleaded and I just put some Techron in the tank as well. You think there's some buildup in the injectors or distributor?

I suspect you have a bad fuel distributor. The age of your vehicle is time for this item to fail. Unlikely that some "magic juice" of any type in the gas, oil or otherwise will solve the problem.

Ouch. Not what I wanted to hear. What should I be looking for on the fuel distro and the injectors?

Well I've checked the wires and they're all within 1.1-1.3k ohms. I'll do a compression check this week and start in on the fuel injectors as well. Thanks for your help!