1989 500SE - Rough starts
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Newbie
Joined: Nov 2013
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1989 500SE w126 and 1971 250CE w114
1989 500SE - Rough starts
Hi all. Hoping someone may be able to assist. My 1989 500SE is having issues at start up. It appears to be running rough, rich and off-cylinder for about 15 minutes after firing it up. Once completely warm it starts to run smooth as silk. It sometimes seems to have fluctuating idle also during this rough period.
Standard sitting idle when it's running well is about 750-800rpm. Could this be the Idle control unit? Hoping not as it's an expensive part in these cars.
Any help greatly appreciated.
Thanks :-)
Standard sitting idle when it's running well is about 750-800rpm. Could this be the Idle control unit? Hoping not as it's an expensive part in these cars.
Any help greatly appreciated.
Thanks :-)
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Joined: Feb 2015
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'91 560SEL '93 400SEL
Aha! And this is the issue I had with my '91 560SEL which prompted it to be taken to the repair shop fifteen months ago. If you let this problem go on longer the little black box module which is failing and causing this issue only gets worse and you will eventually begin experiencing random complete shutdown of the engine, so I do advise taking care of it ASAP. And in my case when the module got really bad it took out the Overload Protection Relay.
For reasons I can't begin to fathom my receipt which named the culprit part is not in the folder with the rest of my vehicle expense records, but if I find it and no one else has managed to come up with the name of what it was I'll post it here. And I do seem to recall it being a rather pricey item.
For reasons I can't begin to fathom my receipt which named the culprit part is not in the folder with the rest of my vehicle expense records, but if I find it and no one else has managed to come up with the name of what it was I'll post it here. And I do seem to recall it being a rather pricey item.
Thread Starter
Newbie
Joined: Nov 2013
Posts: 4
Likes: 0
1989 500SE w126 and 1971 250CE w114
Thanks for the response. This makes me super nervous... Would the culprit be an Idle Control Valve per chance? Would love to know your culprit if your expense records turn up. Between this and the creaking steering I'm now giving my nails a bit of a biting... If I need an idle control vavle and a power steering pump I'm in for a big hit...
