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Thread: M54 high mileage power restore?

  1. #1
    Join Date
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    M54 high mileage power restore?

    Hi guys,

    I have a 320ci from 2001. Everything is stock and I would like to keep it that way. My question is, without changing anything from the inside of the engine (piston rings, camshafts, etc), what is the best way of restoring some power and getting it as close to the original horses? I gave it a good maintainance when I got it (changing of ALL filters, oil, spark plugs) and I did a fuel system and injector cleaner flush.

    Thanks in advance.

  2. #2
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    How many mile/km are on it?

    The M54 with higher miles tend to have worn VANOS seals and replacing them will return the low to mid level torque.
    1999 2.8L Z3 Roadster,
    2000 3.0L Z3 Roadster,

    There is only one thing more pleasurable than working on a Z3, that's driving it top down on a fine day.

  3. #3
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    Depends on engine condition. High mileage doesn't necessarily mean you're missing power. If the rings are sticky you can gain some power by running high detergency oil for a few thousand miles. If the previous owners maintained the engine properly though you won't have carbon deposits to clean up.

  4. #4
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    Replace both cam sensors and upstream o2 sensors. Trust me, it will make a big difference even though they arent throwing codes.

  5. #5
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    Quote Originally Posted by Muzz258 View Post
    How many mile/km are on it?

    The M54 with higher miles tend to have worn VANOS seals and replacing them will return the low to mid level torque.
    Thank you for your response,

    It has 215k kms on it right now, has alway been well maintained at BMW dealership and as of lately myself. I'll take a look at the VANOS system, thank you.
    Last edited by SanderVdW; 03-02-2019 at 11:51 AM.

  6. #6
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    Quote Originally Posted by dhurley34 View Post
    Replace both cam sensors and upstream o2 sensors. Trust me, it will make a big difference even though they arent throwing codes.
    Thanks for your reply, how come this could make a difference if all sensors are working properly? You think "worn" lambda sensors give a wrong output voltage?
    Last edited by SanderVdW; 03-03-2019 at 03:34 AM.

  7. #7
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    Lambda sensors get lazy as they age. That is, they don’t react to changes in the exhaust stream as quickly as new ones. They can also under-report. That is, the sensor is designed to report unburned oxygen in the exhaust. Old sensors will report that there is less unburied oxygen than reality. So, the fuel/air mixture runs on the lean side. That’s not good for the catalytic converters or performance. I would change the pre-cat sensors especially if they have more than 80k miles on them. The crank and cam position sensors are merely Hall effect sensors. That is, a magnetic field is created at the business end of the sensor. When a metal containing iron passes through the magnetic field the field is distorted. The sensor has a wire that senses that momentary distortion and sends a signal to the engine computer (DME). Now, if those 3 sensors are original I’d replace them as they will fail eventually. The new sensors must be made by Bosch or Siemens as they supply these sensors to BMW. Aftermarket sensors are strictly verboten.
    Last edited by MarcoZandrini; 03-03-2019 at 07:50 AM.

  8. #8
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    Quote Originally Posted by MarcoZandrini View Post
    Lambda sensors get lazy as they age. That is, they don’t react to changes in the exhaust stream as quickly as new ones. They can also under-report. That is, the sensor is designed to report unburned oxygen in the exhaust. Old sensors will report that there is less unburied oxygen than reality. So, the fuel/air mixture runs on the lean side. That’s not good for the catalytic converters or performance. I would change the pre-cat sensors especially if they have more than 80k miles on them. The crank and cam position sensors are merely Hall effect sensors. That is, a magnetic field is created at the business end of the sensor. When a metal containing iron passes through the magnetic field the field is distorted. The sensor has a wire that senses that momentary distortion and sends a signal to the engine computer (DME). Now, if those 3 sensors are original I’d replace them as they will fail eventually. The new sensors must be made by Bosch or Siemens as they supply these sensors to BMW. Aftermarket sensors are strictly verboten.
    Hey, thanks for the reply. I have a degree in Automotive Engineering so I understand the way these sensors work. I just was not aware that the impact was that big on these O2-sensors when they are a bit worn. I will replace them as well then. Along with the VANOS seals and I'll hope this will get my horses back.

    Thank you all for the replies.

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