my 380sl starts and idles at 1000rpm in gear it drops to 800rpm. when you shift drom drive to neutral the rpm goes up 1500rpm and takes several seconds before falling back to 1000. when shifting from reverse to drive as you normally would it will spin the tires. this has to be hard on the drive train any ideas on what the wii fix this problem,

check the idle control valve, this is very accessible near the front of the engine to the right of the thermostat. New valve is about $240 online, same one as MB, it is made by VDO. Maybe FastLane on this site has it. MB charges about $700 for the same part.

Make sure all vacuum hoses are connected and intact.

I am not sure if the warmup regulator would contribute to what you describe.

After that test/verify idle computer followed by ECU.

Send me an email, and I'll send you the testing procedure off the CD. Pretty simple and all you need is a DMM/volt meter.

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Chuck Taylor
Falls Church VA
'66 200, '66 230SL, '96 SL500. Sold: '81 380SL, '86 300E, '72 250C, '95 C220, 3 '84 280SL's '90 420SEL, '72 280SE, '73 280C, '78 280SE, '70 280SL, '77 450SL, '85 380SL, '87 560SL, '85 380SL, '72 350SL, '96 S500 Coupe

Had the same problem with mine. Found a broken wire going to idle control valve. Check wires before you buy a new valve.

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Marvin
1983 380 SL

Yes, found out the same thing also. The connector on the idle control valve gets hard and brittle. You can cut it off and buy some of those butt-end kind of connectors at the auto parts store or radio shack and crimp them on the end. I don't remember what the size is of it, but there is one that fits very nicely in a kit of bunch of them. I have that on my car, has worked very well. Also replaced the temp sensor connector also because it too suffered from a poor connector connection.

I tried taking the original MB connector apart and soldering in there. It's not worth the effort and it is less secure. The solder doesn't hold very well. So the butt end kind of connector works very nicely.

replaced the over load relay the problem went away thanks for all the help

I am interested in what you know about the overload relay, can it be tested and where is it?

I have exhausted all the tests I know to get my 380 idle to be normal. It will run normally and then jump up to 1100 ro 1500 for "a while" and then back down. Nothing seems to change it so the next thing to investigate is the overload realy.

thanks for any hints you can provide.

It's the little red "ice cube" relay sort of above the fuse box. You should have a stable 12V out of pin 87 which powers the lambda control box and the idle relay.

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Chuck Taylor
Falls Church VA
'66 200, '66 230SL, '96 SL500. Sold: '81 380SL, '86 300E, '72 250C, '95 C220, 3 '84 280SL's '90 420SEL, '72 280SE, '73 280C, '78 280SE, '70 280SL, '77 450SL, '85 380SL, '87 560SL, '85 380SL, '72 350SL, '96 S500 Coupe