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Fault Codes, Camshaft Sensor – 1997 BMW 740iL V8 E38

April 16, 2010

Q
I own a 1997 BMW 740iL, which currently has 123,000 miles. Currently it is idling rough when the engine is cold and goes away once the car heats up to normal operating temperatures. The colder it gets meaning 5-20 degrees the worst it runs. I have used an OBDII fault code meter and have come up the following codes:


PO340 (Camshaft position malfunction)
PO170 (Fuel trim malfunction bank #1)
P1173 (Fuel trim malfunction bank #1)
P1174 (Fuel trim malfunction)
P1175 (Fuel air metering control 1)
P1174 (Fuel air metering)
P1175 (Fuel air metering)
P0340 (Camshaft sensor)
P0170 (Fuel trim malfunction bank #1)
P0173 (Fuel trim malfunction bank #2)
P0300 (Cylinder misfire)
P0302 (Cylinder misfire #2)
P0303 (Cylinder misfire #3)
P0305 (Cylinder misfire #5)

Do you have any idea as to what is going on with my car? I have had a set of Bosch Platinum +2 spark plugs installed about 60,000 miles ago and will be replacing them next week with the standard NGK (BKR6EK) plugs. Also I replaced a “Mass Air Flow” sensor made by Bosch about 1 1/2 years ago because of the check engine light coming on. It came on again with the same fault codes about a week later and I was told that since I had previously installed a K&N Air Filter that any oil in this filter would no doubt be getting onto the sensor in this component. Would you recommend that I keep using the K&N filter or go back to a Mann paper filter? I had taken a 3,100 mile vacation trip to Florida several months ago and the car averaged 26 MPG city & highway mileage combined. At 70 MPH I was getting 28 MPG which is incredible for a car this size. This is the first time this car has ever burped or idled rough. What is my problem?

A
You may have more than one issue. Let’s look at some possibilities.

First, you likely do have a faulty camshaft position sensor. I would suggest that we replace the sensor, clear the codes, and let’s see what (if any) returns.

As for the Mass Air Flow sensor (MAF) and the K&N filter, the only time that you have a potential of getting the filter oil on the hot-film or wire in the MAF, is when the filter is freshly oiled (typically when over-oiled). If the filter has been in use for a while, it won’t be releasing any additional oil. When using a K&N, AFE or other oiled filter, we recommend removing the MAF and spraying the hot-film or wire with CRC Mass Airflow Sensor Cleaner (available at most auto parts stores), during the first week after a new or freshly oiled filter is installed. Similarly, I would recommend that you use the CRC cleaner to clean your MAF.

Please feel free to let me know what happens after replacing the camshaft sensor … and cleaning the MAF.

bmw cam shaft sensor

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