Want to conclude this post on the rough running 560SL I have.
I did test the lambda and found 97.5% steady which I considered 100%. So It says,
100% Lambda setting too lean. O2 sensor faulty (short to ground). No voltage or ground at CIS-E control unit or CIS-E control unit faulty. Lambda tester faulty.
I also suspected a bad injector or plug problem.
I tested the O2 sensor output under the passenger floor board. Its output should be .2 volts at start up, then .1 to .9 volts after warm up ( 2-3 minutes) while in closed loop. I suspect that mine is bad. Duty cycle code 100% and the closed loop output is steady around .85. I'll install a new O2 sensor next weekend.
I also tested the heater circuit to the O2 sensor. It showed battery voltage.
Someone suggested pulling the spark plug wires at the distributor to determine the cylinder that was missing. He's a better man than I. It's very difficult to pull the wires off the cap and , sorry, but getting zapped is not fun. Even with thick rubber gloves. I just was not interested.
I did remove each spark plug and check appearance and gap. While doing that I measured resistance. I found one wire with no continuity. So that was my problem.
Check all the others and found another where the wire pulled away form the end piece inside the spark plug connector.
Park Place Mercedes gives the MBCA a great deal on parts the first 10 days of the month at the Dallas location and the last 10 days of the month at the Mid Cities location. The prices, I'm afraid to say, beat Fastlane and the other on line prices.
I got a Bosch OEM set of spark plug wires for $126.
That required a post about the angled spark plug connectors.
http://www.peachparts.com/shopforum/showthread.php?t=127393
I found that the angled connectors were not required for spacing problems. There may be another reason but I can't find one. I'll talk to the dealer guys this week.
The manual does suggest that for a rough idle, first ensure that the electrical spark system is operating normally prior to checking the CIS-E system. This problem proved to be true for my car.
So a new set of wires and the engine is purring nicely.
I also cleaned and gapped the plugs as well as cleaned the disruptor cap and rotor. While I had the air filter off I also cleaned the injector intake manifold area. You must do this carefully to prevent flooding all the electrical equipment or getting water in the intake. I used a degreaser and then carefully washed it off with running water. No heavy stream.
So the end result New wires and she's running great, so far.
Dave