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Thread: M20 525i engine dies once warmed up...

  1. #1
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    Mmm... Crank Position Sensor comes to mind. Got a spare to throw in to test this? Other is MAF.

  2. #2
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    Quote Originally Posted by Bruno
    Actually there is the vent line from the gas car that is rusted out under the car and broken... would that cause a problem?
    I'd be out with a DMM on the air temp sensor and the coolant sensors...

    Also check your O2 sensors (could be duff as they only kick in after 2 minutes or so) and when it's refusing to start, pull the plug off the AFM meter and see what happens! If it suddenly starts running better you've got a vaccuum leak somewhere.

  3. #3
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    I've just thought as well, does it start with your foot on the gas and just refuse to idle?

  4. #4
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    Default M20 525i engine dies once warmed up...

    I am trying to figure out what the problem could be to order the right parts before the car shows up.

    Symptomes:
    Car starts fine cold and runs great until the temperature gauge goes out of the blue area (car warms up), then the car idles funky and dies.
    A couple of starts and the car sometimes restarts or will restart when cold...

    Any idea?
    '85 Euro 635csi Race Turbo, megasquirt, Group A
    '92 525i Touring 5 speed, 3.46 diff, UUC 8.5lb flywheel, soon to be turbo.
    '02 Subaru WRX Wagon with STI springs, bigger sway bars

  5. #5
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    Hey Bruno..... it could be something as simple as a vacuum leak, cracked hoses or it may just need a tune-up. I'm sure it will be easy to find once you get your hands on it....
    M20 525/7 Bore: 84.50mm Stroke 81mm CR 8.5:1, blue printed/dyno & custom chip. Boost @ 6.5psi ~246hp @ 5300rpm / torque @ 269ftlbs. @ 4250rpm

  6. #6
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    Quote Originally Posted by M20Turbo
    Hey Bruno..... it could be something as simple as a vacuum leak, cracked hoses or it may just need a tune-up. I'm sure it will be easy to find once you get your hands on it....

    Actually there is the vent line from the gas car that is rusted out under the car and broken... would that cause a problem?
    '85 Euro 635csi Race Turbo, megasquirt, Group A
    '92 525i Touring 5 speed, 3.46 diff, UUC 8.5lb flywheel, soon to be turbo.
    '02 Subaru WRX Wagon with STI springs, bigger sway bars

  7. #7
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    Thanks I will test all that... Picked up a CPS just in case... I have seen weird things happening with these, including car stalling at traffic lights and weird idle.
    '85 Euro 635csi Race Turbo, megasquirt, Group A
    '92 525i Touring 5 speed, 3.46 diff, UUC 8.5lb flywheel, soon to be turbo.
    '02 Subaru WRX Wagon with STI springs, bigger sway bars

  8. #8
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    tps maybe adjust throttle plate if needed and test, cps probably not but if it dies and won't restart till it cools or you screw with the wire maybe, 02 sensor good chance, temp sensor (air/water) maybe, afm maybe pop cover and clean the trace, icv maybe but is dependent on the tps to work, vacuum leak maybe but it would screw with it all of the time
    all america wants is cold beer warm cat and a place to take a poop with a door on it

  9. #9
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    Ahh... good to know!

  10. #10
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    Well, the problem was the crankshaft position sensor.

    Here is the problem, shady garages are chaning the timing belts and do not replace the cover to protect the sensor. The sensors are touching the waterpump pulley and they get cut.

    This is the second car I have seen like that.

    M20 Owners, please check that your sensors are not touching your pulley and that the cover is still in place....
    http://www.realoem.com/bmw/showparts...36&hg=11&fg=10
    Parts: 13 and 14.

    Thanks guys the garage wanted to charge him $950.00 for a complete tune up and that didn't even include the CPS, they kept the car 2 days and never found the problem so they wanted to start changing parts. As soon as I looked I noticed the cut in the wire. $100.00 later the car was on the road.
    Last edited by Bruno; 04-14-2008 at 01:55 PM.
    '85 Euro 635csi Race Turbo, megasquirt, Group A
    '92 525i Touring 5 speed, 3.46 diff, UUC 8.5lb flywheel, soon to be turbo.
    '02 Subaru WRX Wagon with STI springs, bigger sway bars

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