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  #16  
Old 01-03-2003, 01:05 PM
lleon1999
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Steve:

I am assuming that the OVP refers to the Overvoltage relay. I did replace this relay (around $80 from the dealer) for another problem I was having. Obviously, I discoved that the vacuum to the EZL was disconnected after replacement of this relay. I now have a new overvoltage relay and my idle is high when the EZL is connected to the vacuum.

I suggest following the steps that the manual suggests. Start with the resistance mesurement of the idle valve, continue with the current measurment when engine is at normal operating temperature (current should be 700-1000 mA). If current is OK then you either have a bad valve or an air leak. If current is not OK then check the throttle valve switch, the wiring to the control unit and the other items the manual descibes.

Let me know your progress.

Leon
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  #17  
Old 01-03-2003, 03:34 PM
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Join Date: Jan 2002
Posts: 29
Leon - Thanks for the tips. I was checking things again and we have exactly the same problem. When I got the 30 degrees with the vacuum off I hadn't let it warm up. Warm I get 13 with the vacuum off. I have checked power and 750 ohm resistor both OK. I already checked and cleaned the idle valve and it is OK and doesn't affect the timing. I am running out of things to test. I am fearing the ignition control module (EZL)! Maybe I'll disconnect the vacuum and sell it! (Just kidding, I think!)
Steve
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  #18  
Old 01-04-2003, 02:25 AM
lleon1999
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Steve:

It may not necessarily be the EZL unit. In fact, the people I spoke to told me that these units are very robust. I am not sure which resistance you checked, but I was suggesting testing the resistance of the idle valve with the engine off and the connector to the valve disconnected. If I recalled correctly is should be around 5 ohms. You should check the current through the idle valve, that the inputs to the control unit are correct, that the wiring between the inputs and the control unit are good, and that the control unit itself is good (unit is located inside the car). I am going to do all these tests on mine when it stops rainning!

The story on my car is that it was purchased by one of the teachers at my son's school, serviced by a Mercedes mechanic during that time before she sold it to me. She had not idea that the radiator was partially plugged up (not as obvious since water was flowing through it without any obvious restrictions) and it also had the vacuum advance to the EZL unit disconnected. It passed the state smog test (this was illegal since only a deviation of few degrees on the timing is allowed -the car was off by at least 7 degrees!).

So this is the story on the "professionals" who worked on my car before I owned it....This is not to say that there aren't many honest and knowledgeble mechanics out there - not just pats changer guys!


Leon
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  #19  
Old 01-08-2003, 02:07 PM
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Join Date: Jan 2002
Posts: 29
Leon - Interesting history, I think every car has a story. About dealers, I think most have some knowledgable mechanics, it's just that they are not necessarily the ones that work on your car. Before this car my wife had a '77 240D that a I got form a guy at work who had it religiously maintained by the dealer from new. When I got it the hood hinges had never been lubed and had seized and enlarged the holes. PS. my brother was a mechanic but not for Mercedes.

Now back to our problem. I have checked a bunch of things and they are all OK. The only thing out of spec (besides the idle timing) is that the dwell is low.

Things I've checked.
1. Idle position sensor.
2. All inputs to the EZL (except crank sensor).
3. Idle control valve, had it out and cleaned and tested it on the bench (5 ohm, opens and closes smoothly). At idle it draws a little under an amp (which should hold it closed).
4. Idle injector (removed connector with no change, so it is getting the gas from somewhere else).
5. OVP (didn't check Zener cutoff but power gets to all the right places).

I also had my wife put it in gear and step on the brake and the advance lessened both with and without vacuum. This leads me to think that if the engine slowed to the spec the timing might be right as the only EZL inputs are RPM and vacuum.

I am about to break down and get a scope and start scoping (a lot cheaper than an EZL).

Does anyone have the pinouts of the diagnostic connector? The print is too small on the schematic and I can't find them anywhere else.
Thanks
Steve
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  #20  
Old 10-22-2003, 09:22 PM
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Join Date: Oct 2002
Location: Colorado Springs
Posts: 481
steve did you ever get this figured out?
m
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Martin Ingram
Colorado Springs
2005 320 CDI
2006.5 VW Jetta TDI
1991 560SEL (179000 Sold)
1972 280SEL 4.5 ('The Lead Sled' 320000 miles when sold.)
1972 220D (225000 when sold)
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  #21  
Old 11-17-2003, 03:24 PM
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Location: Colorado Springs
Posts: 481
bounce

Steve did you figure it out?
m
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Martin Ingram
Colorado Springs
2005 320 CDI
2006.5 VW Jetta TDI
1991 560SEL (179000 Sold)
1972 280SEL 4.5 ('The Lead Sled' 320000 miles when sold.)
1972 220D (225000 when sold)
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  #22  
Old 11-17-2003, 10:54 PM
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Join Date: Jan 2002
Posts: 29
Martin, in a word no. I haven't worked on it for awhile. I think the car was running open loop. Someone loaned me an idle computer and that wasn't it. I moved fuel injection screw 1/4 turn leaner and that helped a lot. I didn't want to mess with it any more until I had a scope to set it correctly. Last week the timing chain broke so now I'll be asking a lot of questions on that project when I get to it.
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  #23  
Old 11-18-2003, 05:21 PM
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Join Date: Jan 2003
Posts: 253
usually, it will give you warnings before a timing chain breaks. just curious, did you hear any noise from the engine when starting cold in the morning ( perhaps many times before the chain broke??)
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