W124 idles extremely rough when operating temperature reached - PeachParts Mercedes-Benz Forum

Hydronuclear · #1 06-26-2009, 12:45 PM

I've had my 87 300E for about a year and a half and this is the first time it's stranded me. A few days ago, I stopped at my office on my way to my other job (my office is only 2 miles or so away from my house). When I got back to my car a few minutes later, it would crank, but refused to start. This has happened before, so I let it sit a few more minutes ... nothing. I bummed a ride to work and when I returned a few hours later, it started right up and I drove it home. When I was pulling into my street, I noticed that it was idling a little rough, but forgot about it.

The next day it started out fine, drove like it was new (I stopped at my office again). Then it wouldn't re-start. A few hours later, I drove it home.

I thought, well, this must be a hot-start problem. I got info on the OVP, checking the cap and rotors (which were replaced les than two years ago by the previous owner), etc.

I figured THIS time I'd drive straight to work. About half-way to my work (nearing my office), the car started sputtering. I was able to park it by my office, and it was REALLY running rough at this point.

It wouldn't restart. It was at this point that I realized that the problem started as soon as operating temp was reached.

A few hours later, (the car hadn't completely gone cold yet), I managed to get it cranked and proceeded to slowly head home. It DID NOT like idling, but I was surprised that as soon as it sputtered into 2nd and 3rd gear, it would smooth out and ran great (until I had to get it back to idling). I somehow made it back to my house...

I had installed new BOSCH Platinum Plus plugs two weeks ago. I'm wondering if that may be the culprit (it had run great until this week).

Might a bad cap and/or rotor/wires lead to a stumbling idle when the car is at operating temp?

Thanks for reading my dissertation...