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  #46  
Old 06-14-2007, 07:56 PM
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When the engine is cold the management system makes it run a little rich until warm. This extra fuel can mask a bad FD. You could adjust the mixture once it is warm and intentionally make it on the rich side and see how it runs.

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78 Corvette Stingray - 3k
82 242 Turbo Volvo - Manual - 270k
86 300e 5 speed manual - 210k
87 420sel - 240k
89 560sl - 78k
91 420sel - 205k
91 560sel - 85k
94 GMC Suburban - 90k
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  #47  
Old 06-14-2007, 11:51 PM
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Have you done the test on the EHA? It dose sound like a fuel balance problem, do the 50% x11 setting and see if your EHA is set at -0 to +0 and reset your mixture to the 50% if this fails then go to the suggestion Dave has given on fuel distributor.
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  #48  
Old 06-15-2007, 11:33 AM
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Surging 88 420SEL

Your idle numbers seem a little high, Thats why everyone keeps pointing fingers at the valve but off idle the valve has little on nothing to do with smooth running.
Even though you say the plugs and wires are new, pull the plugs and look for oil fouling and possibly closed gap , carefully inspect the cap for tracking as well as the rotor.
You should also check the coil for good spark.
Mike
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  #49  
Old 06-16-2007, 08:22 PM
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I fixed the idle problem it now always idles about 650-750.
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  #50  
Old 06-16-2007, 08:42 PM
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i had a 380sl that did almost the same after a tune up.. mb took the car and after 2 months of replacing everything that everybody has talked about the dealer thru their hands up and contacted mb of nort america. explained the problem and they sent a rep down and it took him all of 30 sec on a scope and said replace the new wires.. they were bad and that was the only problem. the wires were not factory but after market and they didn't work..
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  #51  
Old 06-19-2007, 10:40 PM
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The wires are new but I forget the brand, I know they are German though. Does anyone know where I can get a rebuilt fuel distributor or is it worth trying to rebuild it myself. I have never had the opportunity to see the innards of one of these things.
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  #52  
Old 06-20-2007, 10:19 AM
david s poole
 
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specialtauto.com-----should be around $450 exchange.
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"Fortune favors the prepared mind"
1987 Mercedes Benz 420SEL
1988 Mercedes Benz 300TE (With new evaporator)
2000 Mercedes Benz C280
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  #53  
Old 07-13-2007, 12:43 PM
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Well I replaced the Fuel Distributor and EHA, didn't effect anything. The car still stumbles under acceleration when fuel is needed fast. I am so frustrated at this point that I don't know what to do anymore. Any suggestions...
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  #54  
Old 07-13-2007, 12:46 PM
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Forgot to mention I did the new ignition coil earlier too.
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  #55  
Old 07-13-2007, 12:59 PM
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You did not tell us what were the results of the coolant temp sensor (also called fuel injection temp sensor) ? Check if the resistance changes by a factor of about 8 to 10 as the engine temp goes from cold (20 deg-c) to 80 deg-c.

You have changed a lot of parts, you should disconnect the battery for 10 minutes incase the computer needs a reset.

Also it maybe a good idea to again summarize what you have changed and what the problems are now (also the exact model of the car). I would not change any more parts until there is a definite diagnosis. Most of the parts you have changed could have been tested to a certain extent with a multimeter and a fuel pressure gauge.
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  #56  
Old 07-13-2007, 01:06 PM
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And also what happens when you test the air sensor potentiometer (a black part attached to the air sensor unit, the unit with a plate under the air filter box, the potentiometer is attached to it with its connector available towards the front of the car), I am assuming you have a mechanical fuel injection system. With the car off, if you measure the resistance across the middle pin and one of the other pins (cant tell which one), you should get 1 to 2K when the air sensor plate is all the way to the top. Now when you press the plate gradually downward, the resistance should smoothly increase, there should be no jumps larger than 2K, specially no open circuit (i.e. large resistance, infinity) spots. If you get jumps, you need a new pot (a new one is hard to find now). I dont think it is easy to clean this, the problem likely occurs because the area on the pot is worn out.
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  #57  
Old 07-13-2007, 01:11 PM
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I have continually tried the reset by disconnecting the battery after every change that I did. The car again is a 1988 420SEL. I have a nice old 88 560sel that runs perfectly and I can borrow parts from. I am not sure where exactly that coolant temperature sensor you are referring to is located or even what it looks like. If you could tell me I will swap it out right away and find out if that is the problem. Thanks Again...
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  #58  
Old 07-13-2007, 01:21 PM
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It does seem to be temperature related because the problem gets worse as the engine gets warmer so I think that coolant temperature sensor should be what I will look into first, the problem is I am having difficulty finding it.
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  #59  
Old 07-13-2007, 01:26 PM
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I am not familiar with this car, just am familiar with the KE fuel injection system, and this component is very important besides the air intake sensor. This should be on the engine somewhere, a two pin sensor most likely, some cars have a 4 pin sensor. You can look at the parts configuration for your car at performanceproducts website. It should be called a coolant temperature sensor or a fuel injection temperatire sensor or just fuel injection sensor.
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  #60  
Old 07-13-2007, 02:15 PM
david s poole
 
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should be a green sensor with two separate connectors plugged on the top.[look same as plugs on brake wear sensors]

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European Performance
Dallas, TX
4696880422

"Fortune favors the prepared mind"
1987 Mercedes Benz 420SEL
1988 Mercedes Benz 300TE (With new evaporator)
2000 Mercedes Benz C280
http://www.w108.org/gallery/albums/A...1159.thumb.jpg
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