'86 560 SL engine misses

Help...I just bought a real clean 560 SL from Florida with 103,000 miles. Sometimes the car runs great, real smooth, and then for no reason it starts running rough which seems like a miss to me. I checked the plugs, they're fine, the rotor was a little corroded so I cleaned it up and it ran super for about 50 miles then it started all over again. Anyone have an idea what the problem might be?

[Please Help]

The following is an exerpt from another thread. Hope it helps

Andy


>thx for the input. I have actually searched and read all the >posts, and I have the following as my plan to inspect:
>1. idle control valve
>2. idle air valve
>3. Fuel injector nozzles(holders, hoses, guides)
>4. recheck all vaccuum lines

>I would appreciate if there are more tips/guidance from the >experts.

>thx again,
>emmy

>You missed my thread on the fuel distributor screens getting >partially plugged from rust from a rusted fuel line. After 1 year or >more of a miss at idle - new fuel lines and cleaning the screens >to the injector lines cured my miss at idle. Just to be clear - my >miss was not major - just annoying to see engine move and feel >the random miss. Pick up and acceleration was perfect.

[tivoliman]

Not running smooth - same thing

Only I have 170K on the 86 560SL

Comments and suggestions are appreciated.

Chnaged the fuel filter 1,000 miles agao.

[Bzoo]

Dan, I'm having the same problem on my 400 E and have found numerous posts on similar symptoms and they respond there is a resistor boot problem. I'm ordering mine monday to see if that solves the ptoblem...I've done everything else already. Hope this helps. Just do a search for "engine miss" or " rough idle". Good luck.

Brian

[tivoliman]

My resolution was "never fully" understood. One day it just started to run great again.

I did do the following:
1 - Two (2) bottles of Techron Fuel System Cleaner (I think this stuff actually works)
2 - Repositioned the spark plug wires, cleaning them and ensuroing a good fit on the spark plugs.
3 - Removed, regap and replace the spark plugs.

I just did "block and tackle" type stuff.

[yeldogt]

I have posted on this before -- I do not know why this is the case with the 560 motor. All of my problems over the years with different cars doing this has always led to the plug wires and then mostly to the spark plug boot1

It may be that the location of the wires in relation to the heat of the engine, I do not know. I have also tried to check the condition of the wires by spraying water on them thinking that this would pinpoint a bad wire. No Luck -- The only way that you can be sure to find it is to put the car on a scope.

If you think the wires are original -- just replace them! They are not cheap but they will go bad on this car eventually.

The cost of one fix with a scope will pay for the wire set.

Another interesting thing is at two different dealers -- they also always advise putting injector cleaner in the tank.

I have never replaced an injector on any 560 but they both recomended using slick 50 injector cleaner -- I do not know -- I was always told that injector cleaner in the tank was a waste of money!