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  #1  
Old 12-24-2010, 07:28 PM
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1990 300e missfire/studdering above 2000rpm

Car ran great before replacing water pump and resealing top timing cover. Crank position sensor was removed and re-installed. Car starts just fine,idles smoothly, and then wether in park/neutral/drive, slow acceleration fine up to 2000 rpm, then bad misfiring and/or stall. Keeping below 2000rpm the car shifts normally and at about 45mph I can drive no faster without going over 2000rpm and misfiring/stall/severe studdering. No dash warnings lighting up other than when they should be prior to start. Fuel filter was changed 10,000 miles ago.Have checked all engine compartment electrical plugs, all are in place, and all connectors are clean.

happy holidays!

donnnnnoooooo
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  #2  
Old 12-24-2010, 07:33 PM
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Sounds fuel related to me. I'd check fuel flow rates at injector/distributor/fuel pump.
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  #3  
Old 12-25-2010, 07:15 AM
Rebe
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You might want to re-check your work on the distributor. If you accidentally cracked the cap or the rotor wasn't installed right or the wiring got pinched in the install could be the culprit. It's very easy to destroy those ignition cables installing the wiring cover tray. If it ran good before the work you did, that would be a good place to look. That's one of the first basic places to address with poor performance on those engines.
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Old 12-25-2010, 10:11 PM
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Thanx, will check distributor work.Assuming, work was done correctly, I do have a multimeter and would appreciate any tips or suggestions as to which terminals/sockets to test.

Merry Christmas

donnnnoooooo
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  #5  
Old 12-26-2010, 07:05 AM
Rebe
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If you don't have it search for the cd, it will give you all the resistances. Also, double check the crank sensor for good connection there, as well as, within tolerance.
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  #6  
Old 12-28-2010, 01:46 AM
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hello,please do yourself a favor disconnect the E.H.A system valve,its a large black sensor bolted with 2 stainles screws to the back of the fuel distributor,see how it runs then.
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  #7  
Old 12-28-2010, 01:16 PM
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Quote:
Originally Posted by mlozzi200478 View Post
hello,please do yourself a favor disconnect the E.H.A system valve,its a large black sensor bolted with 2 stainles screws to the back of the fuel distributor,see how it runs then.
You must also disconnect the O2 sensor. For an open loop predefined setting it requires both the O2 sensor and EHA disconnected. You can manually adjust the mixture from there to see if it helps. It may determine where the issue can be.
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  #8  
Old 12-29-2010, 07:35 PM
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o2 sensor

I just wanted to comment but i believe once the EHA is disconnected there are no inputs from any of the electronics including the 02. The motor is simply running in a purely mechanical mode unless i have that wrong??
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Old 01-02-2011, 08:32 AM
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and once i remove it what am i looking/listening for?
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  #10  
Old 01-03-2011, 05:56 PM
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Try to keep this as simple as possible-the five aspects:

Fuel
ignition
vacuum
electronics

or five

With the EHA disconnected the car is is running in open loop so those sensors(electronics) are out of the eqaution-drive the car with the EHA disconnect and see what happens-it may be hard to start but it wont hurt it. If you have some equipment you can start checking things like fuel pressure. Im not an expert but i think you need to either spend the time on this forum researching which is time consuming or take it to a shop and start runing some tests i.e vacuum, fuel pressue, etc.
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  #11  
Old 01-12-2011, 03:51 AM
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I am having similar problems with my M103 3.0 300E 1989.

Starts fine and car drives slowly fine. However, if I try to accelerate faster, engine stumbles and stalls. Engine will then be difficult to start, but cranks just fine. 110k miles on the motor.

I am thinking it is my fuel filter, so i will try replacing that item first before searching elsewhere.
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  #12  
Old 01-12-2011, 05:27 AM
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John5788, replacing the fuel filter sounds like a good idea. Also, consider replacing the Oxygen sensor if you're not sure when it was replaced last ... should be done every 60,000 miles. Check the condition of the distributor cap, distributor rotor, spark plugs (replace every 30,000 miles) and ignition wires. Replace, as required.
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