i measured my duty cycle at 97% and turned the air mix screw and no change what do i check or do now? at idle i am very rough. new plug and wires and when you undo the icv the rpms go up. so where do i go from here?

Can't believe nobody responded to this...I am having a similar problem.

I had an '87 560 SEL with the same problem, my was started as an intermediate rough idle and changed to continuos rough idle. Recommndations that people gave me were as follows:
Check for vacuum leaks
Techron fuel injector cleaner
Change plugs, caps and rotors
Change ignition wires
Replace fuel injectors (irritating job, rubber parts, crack like thin walled glass)
Then when all these failed, and they did all fail, I took it to the dealer and they told me the fuel distributor was defective and needed to be replaced
$1,800 plus labor plus tax. I sold the car, not because it was a bad car, I just couldn't handle the bad idle, and was not going to put over $2,000 in a car that i paid $2,000 for in the first place.
I replaced it with another 560SEL, this time an '88. This one as well once it hit 127,000, same bad idle, replaced the same parts as before no change again, sold it againbecause the rough idle was driving me nuts, and replace it with a 300SDL.

So I can suggest you start with the vacuum leaks, then move on to , the fuel injector cleaner, you've already done the caps and rotors, well there's the ignition wires, then the fuel injectors. Then theres the possible diagnosis of the fuel distributor. My advice, don't fall in love with the car, and don't let it bankrupt you, there's alot of these out there at reasonable prices. If the idle bugs you and you can't fix it, sell it!

__________________
jcciem
'94 SL5000 60,000
'91 350SDL 545,000
'91 350SD 197,000
'00 E55 AMG 77,000

Had the same symptoms with 86 560 sel. Then one day it just quit no spark
replaced crankshaft position sensor.Idles great now.Who knew.

Your readings are useless so you need to find out why. In all instances of useless tool information one needs a standard. The standard here is the key on engine off duty cycle. On a federal car it is 70% on a California car it is 85%. Verify that condition and we can go from there.

Also the instance of a fixed duty cycle is often a code. The codes can vary but are usually not for 100% duty cycle (figuring 97% rounded off) as a pegged mixture is also fixed at the end points. This is why one needs to calibrate ones test and why more info is needed such as the year model.

__________________
Steve Brotherton
Continental Imports
Gainesville FL
Bosch Master, ASE Master, L1
33 years MB technician

ok here is what i have done.new injectors and seals and holders and hoses. turn on the key reads 97.6 crank it up will flucutate at 120 to 97,also it idles still no fluctuations. the one thing that gets me is when driving when slowing down the economy gauge goes into the red and sometimes just kills, why does this happen?

My grandpas 560sel did that, I though the idle was cool . Its a vacuum leak also based on your gauges as stated above. For us it the filter housing in which itself and nearly all the vacuum tubes around it were knocked off. the car rocked left and right in idle it was awesome

__________________
1997 Mercedes E320 Turbo
Garrett T3/60-1 Turbocharger
Custom Water Intercooler Setup
352rwhp/366rwtq @ 8.6psi in '08

http://img78.imageshack.us/img78/1051/log7smallay9.jpghttp://img66.imageshack.us/img66/740...s3smallox0.jpg