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  #1  
Old 12-27-2003, 07:28 PM
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Bad gas mileage

I was thinking O2 sensor until I read that the car has to be warmed up before the O2 sensor activates. Since I have black smoke coming out of the exhaust right from the start, when the engine is still cold and my "economy needle" goes well up even at cold idle, I was wondering which sensors the engine draws information from when running cold.
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  #2  
Old 12-27-2003, 09:36 PM
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Coolant temperature sensor is one of them.
You have black smoke coming out from the start, all the way to normal operating temperature?
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  #3  
Old 12-27-2003, 10:23 PM
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Sounds like a bad fuel distributor, sadly. They are expensive....

Peter
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  #4  
Old 12-27-2003, 10:24 PM
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Yes I have, the car runs well but at times idles faster than at other times.
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  #5  
Old 12-28-2003, 12:03 PM
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Get the pressure regulator and fuel distributor pressures checked -- it's possible that the regulator is bad, but this is typical of a bad fuel distributor.

Peter
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1972 220D ?? miles
1988 300E 200,012
1987 300D Turbo killed 9/25/07, 275,000 miles
1985 Volvo 740 GLE Turobodiesel 218,000
1972 280 SE 4.5 165, 000 - It runs!
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  #6  
Old 12-28-2003, 12:38 PM
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Thank you, I will do that.
If they check out can you think of other possible causes?
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  #7  
Old 12-28-2003, 12:52 PM
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Defctive EHA of bad computer, maybe. Not likely.

Plugged return fuel line causing excessive fuel pressure.

Peter
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1972 220D ?? miles
1988 300E 200,012
1987 300D Turbo killed 9/25/07, 275,000 miles
1985 Volvo 740 GLE Turobodiesel 218,000
1972 280 SE 4.5 165, 000 - It runs!
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  #8  
Old 12-28-2003, 01:35 PM
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Thank you psfred, much appreciated advice.
Because of some health problems I won't be able to deal with these things till sometime in February, however will let you know what we find.
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  #9  
Old 12-28-2003, 01:45 PM
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Well that gives you plenty of time to read about "closed loop control" and EHA current.

Sounds to me like the mixture is just set too rich and the control system is overwhelmed.
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  #10  
Old 12-28-2003, 02:06 PM
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Steve I have read your posts on "closed loop control" and am sorry to say it is way above my head. What is more, where I live it is difficult to find a mechanic you wants to tackle these issues. Even the dealer closest to me does not seem interested in troubleshooting when it means more than reading codes.

However, the issue of the mixture being set too rich and the control system being overwhelmed intrigues me. Why and how could that suddenly happen?
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  #11  
Old 12-28-2003, 02:22 PM
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Well if it suddenly happened (that wasn't mentioned), then adjustment is less likely to be the answer.

It still requires looking at EHA current and whether closed loop is achieved before finding what is causing it.
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