90 560 SEL, several questions

Just purchased my first Mercedes, decided to go with the top of my wishlist and went with the 1990 560 SEL. A couple of items need repair, so I thought
I would pose questions to the group and see if anyone has experience with these. Just for background, this car has 190,000 miles on it.
1. Sunroof.. Power sunroof does not open. Fuse appears good, same fuse as front seat heat, heat works.
2. Engine misfire.. Car seems to be missing on one or two cyl, still drives well, most noticable at stoplights.
3. High idle.. Wants to idle at about 2000 RPM. Can't be normal, this means that I can take my foot off the gas and still maintain 40 mph. Also results in some very hard shifts into drive or reverse.
I have not purchaced a service book for this car yet, will be looking for that shortly, but any suggestions in the meantime would be appriciated. Thank you in advance.
Aaron
High school -1999.... Firm believer that Mercedes were for yuppie scum 1999.... Drove one for the first time, a 1985 560 SEL, became a believer 2005.... An owner at last, 1990 560 SEL, I think it has every option except the power rear sunshade
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df wrote:

No service history? Get it checked by a reputable indie MB mech, soon. Where are you located? The people here or in the forums should be able to point you to one.

Maybe just the cable, hopefully no rust inside once it's open.

...and hopefully, just the electricals, orthe fuel filter, if not see below:

190,000 miles you say? Fuel System, electricals, etc. Time to look at the timing chain and transmission, and bushings, and brakes, and suspension, hmmm...

Try the forums:
http://forums.mbworld.org/forums/forumdisplay.php?fa
http://www.mbnz.org/forums/forums/forum-view.asp?fid 
Read the FAQs there.
Hope you paid enough for a good one, or it starts drinking money, and I don't mean gas.
Although, I guess, that wasn't a consideration? ;-)
http://www.fueleconomy.gov/feg/noframes/6850.shtml

regards, WS
--
change to leews to mail

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Re: sunroof
The drive on my 80 300SD had the same symptoms, it just stopped working one day. I came to the conclusion the motor was shot. While starting to remove it, it suddenly came back to life and has worked several years now perfectly! I think the motor must just have stopped at a bad spot and needed a little push.
On my car there is an emergency fitting on the drive mechanism that you can put a socket wrench on to turn it by hand. It's located in the left rear trunk area, near the antenna. I'd try turning it a bit by hand and then see if it works. You can also find the motor there to see if it's getting juice. Good luck!
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It could be the idle control valve, an electric solonoid at top center engine in front of throttle assembly. I have seen the two wires that go to this get disconnected or break off. If the wires are good, a little carb cleaner may help. There is also an electronic idle control circuit. It is a little black plastic box I think somewhere around firewall below windshield wipers or located inside car on firewall. http://www.mr-auto-parts.com/item.wws?mfr=GENUINE&sku=MBZ006015&price42.03&orpartno 60811&cookieID=1O60W55TV1O60W8JR6&drillid=9&image
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Motor probably needs a tune up. You're right that it should not idle at 2K rpm, more like 600 +/- rpm.
Some V-8s have a firewall mounted idle control module (logic board). These boards crack and their solder connections fail. They can be had as rebuilt units. I believe a high idle is the default mode when the logic board fails. You need to determine if your model has this idle control system, complete with an engine mounted motor/actuator.
The miss could be from bad spark plugs and / or ignition cables. An ohm meter can be used to check the continuity of the ignition wires. Don't overlook the distributor cap.
Factory manuals are available in CD-ROM form from M-B dealers. These are unindexed and not easy to use; their graphic quality is not good as they appear to be scans of paper manuals. But they're better than nothing, especially when working on a complicated model like yours. Third party manuals tend to cover too many models and years and in some instances omit pertinent data one needs mid-job to know the "next step". Sometimes on can find paper versions of the M-B manuals on e-bay. Also take a look at: http://www.tmcpubl.com//mercedes.html
Good luck in sorting it out.
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Also see: http://www.books4cars.com /
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Another thought about the misfires. Dirty fuel injectors might cause this but first check the spark plugs and ignition cables. Add some Techron or other fuel system cleaner to the fuel. Injectors can be professionally cleaned but need to be removed for that service.
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On Tue, 29 Nov 2005 17:25:33 -0800, "T.G. Lambach"

======I once had an experience with a late 1980s Ford Taurus that would start idling so fast that the car would go down the road at 40 mph if left in drive. It turned out to be bad spark plug wires. The computer, in response to misfires, raised the engine speed.
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That was a mistake. Should have paid more money and bought one in excellent condition with low miles.
cp
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"That was a mistake. Should have paid more money and bought one in excellent condition with low miles"
A bigger mistake was not taking the car to have it evaluated by a mechanic with experience on these before buying it.
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- Absolutely get the repair manual on CD. If you cannot afford a new Mercedes, you probably cannot afford to have the dealer work on your old one. Some CDs have component locator diagrams so you can find all the things hidden in strange places. The diagrams can be difficult to locate on the CD, though. IIRC, it is found under a button called "Component Location" in the wiring diagrams.
- There is a lot of stuff between the fuse and the sunroof. Trace through it all and diagnose before your replace, you will run out of money before they run out of parts. Find an on-line parts store, I like http://www.bimmerzone.com but others writers here have other preferences.
- Rough idle is probably not air or fuel filters, but you should check/replace if you do not know the service history, along with oil and oil filter. A car with this many miles/years has lots of little places that may be marginal. Plugs, ignition wires and distributor rotor are a good place to start. Some of the many vacuum hoses and diaphrams in the engine are probably leaking. Check the ignition timing and idle fuel mixture.
- High idle is, as pointed out above, probably the idle control unit, but check the idle valve first and check for other air leaks into the manifold. Procedures are on the CD or search this group. See: http://www.slack.net/~thundt/mercedes/high_idle_hell.htm for more information. Also for having it rebuildt see: http://gdl-online.com/begin1.html They have a good reputation, although I have not used them myself.
- Yes, you should have had the thing checked first or bought a better one or won the lottery, but you didn't. What you do have started as a great example of automobile engineering. It is tired and needs some TLC. Spend some time enjoying it in the garage as well as on the road and you may end up with a really enjoyable car that you can be proud of. Don't get rid of the Toyota just yet, though.
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Yes, don't be disencouraged. Most of the things seem to be repairable if you have the necessary patience, time, enthusiasm.... and perhaps money (at least if you want it done by a garage).
1) inside the sunroof drive unit (in the trunk near the antenna) are two switches, which sense the position of the roof (or rather the drive cable to the roof). The switches may have bad connection or the unit may be out of alignment. There is a white knob on the drive unit. It can be pulled out to "adjustment position", in which it disengages from the drive cable. The drive unit gear can then be turned by the knob independently from the sunroof. Turn it several turns cw and ccw and listen when microswitches are actuated. With the sunroof closed (which I suppose it is), the drive unit shall be aligned just in between the the two switches actuating. Then push in the white knob and see if it works. If it works, align it until the sunroof closes correctly after having been opened or lifted.
2) I'm not familiar with your particular engine, but I have gained a little knowledge on the CIS-E injection system. If it actually misfires on one or two cylinders, I would take a look at spark plugs and distributor. It could also be wrong mixture, which is controlled by a computer through the EHA (Electrohydraulic Actuator). The problem could then be the EHA itself or the inputs to the computer, which are RPM, speed, coolant temperature, intake air temperature, throttle position switches, altitude sensor, airflow sensor and oxygen sensor (from catalyst). So sources could be many. I would check the Oxygen sensor.
3) Idle speed is also controlled by the computer through the idle speed valve. So problem could be the idle speed valve. Or it could be wrong mixture as above. Perhaps the alignment of the airflow sensor.
If you have the courage and time to play mechanic, you should - as one source of information - subscribe to www.alldatadiy.com.
Good luck
/Jens
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Yes, I've learned to spend more on a better car than spend less on a crappy car and then spend more trying to make it better, which it will never become as good had a better condition car been bought.
cp
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