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  #1  
Old 07-17-2012, 05:01 PM
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82 380 SL - Surging Idle

So I've been troubleshooting this for a couple weeks now. I have a surging idle when the car is parked and sometimes it dies. The car drives great and has plenty of power, but when idling is will commonly surge up and down. I started troubleshooting this as a vaccuum leak and I found a couple cracked hoses and one hose disconnected which I've resolved. Still have the issue although slightly better. Next I cleaned the Idle Control Valve thoroughly and checked operation by applying 12 volt to the valve. Works great. Now what? So I pulled the 40 degree temp sensor and jumpered it and this seemed to resovle it. Drove it for a day and the issue comes back as before. I experimented with this temp sensor plug pulled, jumpered and on the sensor and still have the idle issue. So now I'm thinking it could be a the Idle Control Unit. I pulled the board and inspected it with no obvious cracks, burnt resistors or anything else like that. Also pulled the Overload relay and tested it for operation and the relay works fine and the diode seems to work fine. Relay works, diode seems to work.

My question is this: is there any bench testing method for the Idle Control Unit? Could this also be the warm up compensator? Is there a bench testing method to ensure proper operation of that?

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  #2  
Old 07-18-2012, 11:15 AM
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http://www.peachparts.com/shopforum/sl-forum/233241-380-sl-idle-oscillates-between-500-750-rpms.html or http://www.peachparts.com/shopforum/sl-forum/273277-voltage-icv.html
may help

air and fuel - the two ingrediants to a lopeing idle , gotta check everything that controls those two factors
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Old 07-18-2012, 12:44 PM
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Thanks meltedpanda. I read the first post you linked before I posted and went through the same procedure to no avail. The second post is interesting and I'll have to check my voltages tonight. I know I was only getting 5 volts at the Idle Control Valve when I last checked it, so that seems low. It does function on 12 when I tested it and the idle jumps up to a steady 1100 if I pull the connector off the ICV.

Where in the manual do they show a test procedure for the electronics? I can't find that anywhere.
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Old 07-18-2012, 12:55 PM
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Nevermind- I found the electronic idle test procedure, I'm just not getting 12 volts.

Is there a test procedure for the overload relay?
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  #5  
Old 07-18-2012, 02:42 PM
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not sure , I always just replaced the "cubes "
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2011 Porsche Cayman - Bond,James Bond
Sadly MERCEDESLESS - ALways LOOKING !
99 E320 THE Queen Mary - SOLD
62 220b - Dolly - Finally my Finny! Sadly SOLD
72 450SL, Pearl-SOLD
16 F350 6.7 Diesel -THOR
19 BMW X5 - Heaven on Wheels
14 38HP John Deere 3038E Tractor -Mean Green
84 300SD, Benjamin -SOLD
71 220 - W115-Libby ( my first love) -SOLD
73 280 - W114 "Organspende" Rest in Peace
81 380 SL - Rest in Peace
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  #6  
Old 07-18-2012, 03:51 PM
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Well I think I solved it! (knock on wood) At lunch I picked up a new ICU. I was checking the part number to make sure they matched and they didn't, did some research and called the remanufacturer Programma and sure enough the old ICU was for an 83-85 NOT my 82. Plugged it in and got a rock steady idle at 750. Niiiice.

I'll update later assuming this was indeed the fix.
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  #7  
Old 07-18-2012, 04:03 PM
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Where does one just "pick up" an 1982 ICU. Haha
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2011 Porsche Cayman - Bond,James Bond
Sadly MERCEDESLESS - ALways LOOKING !
99 E320 THE Queen Mary - SOLD
62 220b - Dolly - Finally my Finny! Sadly SOLD
72 450SL, Pearl-SOLD
16 F350 6.7 Diesel -THOR
19 BMW X5 - Heaven on Wheels
14 38HP John Deere 3038E Tractor -Mean Green
84 300SD, Benjamin -SOLD
71 220 - W115-Libby ( my first love) -SOLD
73 280 - W114 "Organspende" Rest in Peace
81 380 SL - Rest in Peace
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Old 07-18-2012, 04:18 PM
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I've got a great machine shop in Seattle that can always find the right parts and get them quickly- Autosport Seattle. They are awesome. There was actually an Aston Martin DB2 in there last time I was in. Beautiful car.
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  #9  
Old 07-25-2012, 10:43 PM
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I am messing with a 1984-380SL. Do you have the part number for a 1984 and is your idle control unit still good. Where is it located on the SL's. thanks

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