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Join Date: Oct 2008
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running too rich?

so, i think my new 951 is running too rich, but i'm trying to track down possible culprits.

the previous owner put in a lindsey 951 Max performance chip and added a new fuel rail and gauge.

the problem i'm running into is similar to clayperez's post from 7/07: the car is a bit hard to start and then idles fairly rough, esp when cold, though it happens when its warmed up too. when i get on it, there is a bit of hesitation (though noticeable), and after running it up to 3-4K RPM, when it goes back to idle, the engine RPM dips way down almost so that it stalls.

also, i've noticed that there is a good amount of soot on the tailpipe and some spread over the back end of the car.

from reading the posts on this board, it seems the most likely source is the engine is running too rich, likely done by the previous owner so it wouldn't get lean under boost and detonate. however, it seems to be too rich right now; is there any way to adjust the air/fuel mixture to see if it helps? any ideas on what fuel pressure i might need to be running on the fuel rail?

p.s. i finally figured out how to upload a photo of the car below!
Old 10-19-2008, 11:53 PM
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If you have an AFR make sure the fuel pressure is no more than 3 Bar or ~44lbs psi, if so adjust the your fuel regulatory accordingly.
Old 10-20-2008, 06:57 AM
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bought an aftermarket rebuilt bosch AFM, ran progressively richer til I dumped it for a factory bosch
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Trust no one who does not drive a Porsche daily. just kidding. Sort of
Old 10-23-2008, 07:03 PM
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Bad O2 sensor will also cause it to run rich. Mine did that. Fuel mileage dropped about 20% when it happened.

There are tests you can carry out yourself for the sensor.
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Lawrence
1986 951
2002 SLK32 AMG
1987 328GTS
2011 528i
Old 10-25-2008, 07:19 AM
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Mine also went through a period of not wanting to run smoothly when first started. It would also billow black smoke when first started The cause was the idle stabilizer. The armature was worn out preventing it from functioning properly.
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Lawrence
1986 951
2002 SLK32 AMG
1987 328GTS
2011 528i
Old 10-25-2008, 07:25 AM
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Old 10-25-2008, 07:25 AM
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