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Old 09-13-2007, 02:02 AM
a5a1234 a5a1234 is offline
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Join Date: Jul 2007
Location: Vancouver, BC, Canada
Posts: 45
1973 450SE intermittent problem - runs rough, loses power, blue smoke

Hi All. May I describe an intermittent problem I have had with my 1973 450SE (M117.983)?

Most of the time the car runs "clean", but a few times lately (cold start or hot, it doesn't seem to matter) I will get a sudden loss of power, the engine runs roughly and I get "clouds" of thick blue smoke. It seems to start when the car is idling, but once it starts, it continues whether I drive slowly, or more quickly (although I think the problem has always started when I have been idling, or just taking off from a stop). It can happen after 2-3 minutes of idle, or 2-3 minutes of running (so I wonder if the cold start valve might have something to do with it?). I wonder if the idle is set too low, at about 500 rpm? The problem sometimes goes away after running for longer, at traffic speeds, although sometimes I limp home (with my head down) and hope no-body recognizes me! The last two times I have driven the car it has not happened at all - but I have made a point of driving it a little harder. I have looked through the forum, and I understand that this engine's D-Jetronic fuel injection is very sensitive to manifold vacuum pressure (hence my driving it harder, to make more vacuum, or so I think), because I wonder if it might be running rich. Initially I wondered if this might be valve seals. But would that be an intermittent problem? If the engine were running extra-rich for some reason, would that cause the symptoms I describe? What should I look at? Do you need further information?

Please forgive me if my question is phrased badly, or I use the wrong terms, or have wrong ideas - I am quite new to this.

Thanks in advance for any advice you can offer.
Joe
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