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Thread: 08 535i N54 - Idle Surging 1000-1500rpm - TB not functioning - Need advice

  1. #1
    Join Date
    Oct 2021
    Location
    Fort Payne, AL, USA
    Posts
    4
    My Cars
    08 BMW 535i

    Question 08 535i N54 - Idle Surging 1000-1500rpm - TB not functioning - Need advice

    Hey guys, I have 2008 BMW 535i with the 3.0l N54 twin turbo engine. My current issue is the car will surge at idle between 1000-1500rpm up-down-up-down-up-down. My code reader shows the following codes:


    • P1638 - Throttle Valve Position Control; Throttle Stuck Temporarily
    • P1632 - Throttle Valve Adaptation; Adaptation Conditions Not Met
    • P3026 - O2 sensor temperature measurement operating temp not reached (Bank 1 Sensor 1)
    • P1417 - Throttle Control Incorrect Air Supply (Bank 1)
    • P1639 - Throttle Valve Position Control; Throttle Stuck Permanently
    • P2243 - O2 Sensor reference voltage circuit/ Open Bank 1 Sensor 1


    If I clear these codes while the engine is running, it smooths out and the problem goes away. Stays idling at about 700rpms smoothly for ~10mins then starts acting up again and surging.

    I have checked the PCV valve, cleaned oily "MAF"? Sensors before and after the TB (There was a bit of blowby in the intake and it heavily coated these sensors), Checked ALL Fuses I could possibly find, Confirmed Battery Voltage at 12.4V with car off, Confirmed Accelerator Pedal sending input to DME.

    I pulled of air box and hoses so I could see if TB butterfly was moving at all while the engine was running and gas pedal being pushed (While issue is present and After codes are cleared) . It would not move at all. My scanner showed that when idle surge issue is present, the computer is not commanding throttle to open. BUT after the codes are cleared and the engine is running smoothly the computer IS actually commanding the throttle to open yet it still doesn't move.

    This is most definitely making me believe the TB is the culprit of the issue. I'm looking to confirm my suspicions through the help of this forum and more diagnosis on this car. Also, the O2 sensor B1S1, may be bad? My scanner for some reason wouldn't pull up the voltage for this sensor so I was unable to confirm it's operation and switching between 0-1V.

  2. #2
    Join Date
    Oct 2021
    Location
    Fort Payne, AL, USA
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    My Cars
    08 BMW 535i
    Quick update: This morning I removed the TB and verified that the TB motor is working. Still trying to find a pin out to test the throttle position sensors in TB

  3. #3
    Join Date
    Oct 2021
    Location
    Fort Payne, AL, USA
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    08 BMW 535i
    Quote Originally Posted by TMurphey View Post
    Quick update: This morning I removed the TB and verified that the TB motor is working. Still trying to find a pin out to test the throttle position sensors in TB
    PIN 6 & 2 - 11.4k ohms w/ throttle plate closed and does not change with throttle plate movement.
    PIN 4 - No continuity between any other pins
    PIN 1 - No continuity between any other pins
    PIN 5 & 3 (Motor) - ~8.4 ohms

    This is clearly showing an issue with the throttle position sensors inside the TB, correct? But is the motor not on a ‘separate’ circuit that would still allow the throttle plate to move even while the TPS is not reporting back to the ECM?

  4. #4
    Join Date
    Oct 2021
    Location
    Fort Payne, AL, USA
    Posts
    4
    My Cars
    08 BMW 535i
    Quote Originally Posted by TMurphey View Post
    PIN 6 & 2 - 11.4k ohms w/ throttle plate closed and does not change with throttle plate movement.
    PIN 4 - No continuity between any other pins
    PIN 1 - No continuity between any other pins
    PIN 5 & 3 (Motor) - ~8.4 ohms

    This is clearly showing an issue with the throttle position sensors inside the TB, correct? But is the motor not on a ‘separate’ circuit that would still allow the throttle plate to move even while the TPS is not reporting back to the ECM?
    On the wire harness that hooks up to the TB from the DME, Im getting 4.5-5V at Connector 1,3,5, & 6 and 0volts at 2&4.

  5. #5
    Join Date
    Mar 2023
    Location
    Los Angeles, CA
    Posts
    1
    My Cars
    2009 BMW 535i
    Hi TMurphey,
    I am having the same issue surging that goes away when I clear the codes but comes back when I press the gas pedal, with several codes like you are getting. Were you able to figure out the issue with the car?

    Codes
    P1408
    P1407
    DME Boost Pressure control deactivation
    DME Camshaft sensor inlet synchronization
    DME Camshaft sensor exhaust synchronization
    DME - throttle valve actuator jammed (1)
    DME - throttle valve actuator jammed continuously (2)
    DME - Throttle valve

    Several more
    Please help.

    thanks,
    Rey

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