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Old 07-17-2012, 05:01 PM
ArborWrench ArborWrench is offline
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Join Date: Oct 2010
Location: Seattle, WA
Posts: 14
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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