E46Fanatics - View Single Post - Low Reference Voltage on Exhaust CPS Harness
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Old 09-19-2012, 07:40 PM   #24
Registered User
Join Date: May 2012
Location: Nw fl
Posts: 61
My Ride: 2003 325Ci
Well, starting over - I had the codes for bad intake and exhaust cam sensors. After Inspection II service, I changed out the sensors with BMW sensors from the dealer. While researching the change out, I came across the Bentley video showing how to test the sensors. They showed 5V in the video going to the sensor for the reference voltage - which should go to 0V when the lobes of the shafts pass in front of it.

Before and after changing them out, my sensors had 2.7V from the harness.

Before and after, I have very erratic acceleration from a stop, sometime it will take off like a normal car, other times it will almost stall out before revving quickly and jerking forward, and most of the time it will take off somewhere in between these two extremes (this is under any type acceleration - fast, granny).

It has not thrown any codes since I changed them out, however it has stalled out completely last week (I had just started and was moving forward when I remembered I needed something from my house and stopped, put it in reverse and pushed on the gas again and it stalled).

Mainly due to the voltage going to the sensors is why I think this is a possible DME problem. I have also heard that the fuel pump can cause similar symptoms, but with the codes and the voltage, I am still suspect of the DME itself. I tested my multimeter and it read exact-on for 2 different, known batt voltages below 5V, so it is measuring correctly. I will take a look at the harness termination for the two sensors as well as the power supply for the DME itself tonight or tomorrow and report back what I find.

BTW, the coupe is an auto. Did they have the subframe issues like the manuals? Might as well pour through that when I replace the right rear LCA.
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