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Thread: ‘03 z4 just quit starting

  1. #1
    Join Date
    Oct 2018
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    CA
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    2003 z4

    ‘03 z4 just quit starting

    I haven’t used my z4 for a week and decided to use it this afternoon as the sun decided to show. Started right up, idled smoothly, lowered the top and off I went to my first stop...a drug store 2 blocks away. When I came back it just won’t start...cranks really good but just won’t start. Figured might be my key...got my spare key but still no start. Battery was checked by the AAA guy and it was charged. Anybody had this experience? I hope it's just something minor.

  2. #2
    Join Date
    Oct 2012
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    Victoria BC Canada
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    2004 Z4, 1700 Nomad MC
    Crankshaft sensor perhaps....


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  3. #3
    Join Date
    Jan 2015
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    Timaru, New Zealand
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    1,132
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    Two Z3 Roadsters
    Do you have a scanner? Down load the trouble codes and see what clues there are.
    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.

  4. #4
    Join Date
    Oct 2018
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    CA
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    2003 z4
    No trouble codes before this happened....i did start my car this morning and it fired up. Smooth idle and drives great,as if nothing happened. Was thinking fuel pump relay or crank shaft sensor. Drove it for 30 minutes on the freeway and a code came up....something for the thermostat..I doubt that would cause starting issues. Turned engine off and started it a couple of times and everything seems fine for now.

  5. #5
    Join Date
    Jan 2016
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    Ca
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    2001 525it
    Sounds like the classic fuel pump failure, check fuel pressure the new time it acts up

  6. #6
    Join Date
    Oct 2018
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    CA
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    2003 z4
    It acted up again...won’t start..just cranks. Checked my fuel pump relay and it’s working fine. Pain in the ass to ge to for someone my size. I noticed my temp guage would sweep all the way to the red zone if I start my car,i don’t think it does that before when the car starts normally..
    Will study how to check fuel pressure...thanks.

  7. #7
    Join Date
    Oct 2018
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    CA
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    2003 z4
    Fuel rail was dry..so no fuel was being delivered. Won’t a faulty crankshaft sensor tell the ecu to not put fuel on it?

  8. #8
    Join Date
    Oct 2018
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    CA
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    2003 z4
    It fired up again this afternoon. This is what I observed....when I switch on the car and the temp needle goes all the way to the red zone regardless if its a cold or warm engine, it’s not gonna start. If the temp needle just stays on the blue line when cold then it will start. On a warm engine that was recently turned off and it goes to the center then it starts. So I guess it’s a temp sensor thing.....

  9. #9
    Join Date
    Oct 2012
    Location
    Victoria BC Canada
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    2004 Z4, 1700 Nomad MC
    Replace the engine coolant sensor as the part is dirt cheap and you should be able to do it yourself. Get one that is OEM quality or better.

    Once you eliminate this possibility, if the actions you describe continue, you can look further afield for a cause.

    I’d read the engine codes as well if you have an OBED II reader.

    Personally, I’d read codes, change sensor, clear codes, then drive it to see what comes up again.... if anything.




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  10. #10
    Join Date
    Oct 2018
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    CA
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    2003 z4
    No obd codes come up....i read the temp data and my engine coolant temp is at 84*C and my radiator coolant temp is at -45*C. I fiddled with the socket of the radiator sensor and it came back to normal readings. That is when car started and has been idling for some time. Although,i did have 279b come up twice already...will probably change the engine temp sensor together with thermostat. Oh..it did start again this morning,just afraid to turn engine off somewhere far from home as it may not start again....

  11. #11
    Join Date
    Oct 2018
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    CA
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    2003 z4
    Had nothing to do the whole day so I figured I’ll try to start the z4...it fired up and idled smoohtly. Went for a 60 mile drive up the mountains using the Angeles Crest Highway....no issues came up. When I went home, turned engine off...got myself a drink and came back...no start and temp guage on red zone again. Did the cluster test and engine temp reading was 000. Does it mean the engine temp sensor was giving no signal? Anyway,I figured I still have a lot of time before the sun sets so I opened the hood....looked into the thermostat,engine coolant sensor,radiator coolant sensor and the crankshaft sensor,now I pretty much know how to replace those components when my parts arrive. I disconnected those sensors one by one and tried starting the car...still no start and temp guage on the red. Now here’s my question...if the engine coolant sensor is not giving any signal...shouldn’t the temp needle remain in the blue zone?

  12. #12
    Join Date
    Oct 2012
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    Victoria BC Canada
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    2004 Z4, 1700 Nomad MC
    I would say that your engine coolant sensor, as you have discovered, has failed and needs to be replaced.





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  13. #13
    Join Date
    Oct 2018
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    CA
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    2003 z4
    I was already leaning towards my dme or at least the dme relay...but thanks for the positivity Clearancediver.

  14. #14
    Join Date
    Oct 2018
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    CA
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    2003 z4
    Just an update...changed my temp sensors both on the radiator and the engine but still thesame. After waiting for a week for my appointment with an independent BMW specialist, car was finally diagnosed and everything points to a faulty DME. If the engine starts it all goes well...if it doesn’t, it’s because there was no communication with the DME. It’s either the DME or something within the harness. For them to move on,I would have to get a new DME...an expensive proposition. I don’t mind spending that much if that would really cure my starting issues,but they said there is no guarantee. So instead of me getting a new DME they pointed me to another shop that specializes with the DME and electrical stuff. So waitng for another week so that I could bring my car to that new shop.
    i miss drivng my Z....

  15. #15
    Join Date
    Oct 2018
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    CA
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    2003 z4
    Got my car from the shop....changed dme and she starts all the time now. I can finally drive the z again after weeks of waiting for it to be fixed.

  16. #16
    Join Date
    May 2009
    Location
    Minneapolis, MN
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    ...
    Quote Originally Posted by carlsson01 View Post
    Got my car from the shop....changed dme and she starts all the time now. I can finally drive the z again after weeks of waiting for it to be fixed.
    awesome news! been following along, love seeing issues successfully solved
    the stable:
    2003 BMW Z4 3.0i
    2008 Hummer H3 Alpha
    2015 Mitsubishi Outlander Sport

  17. #17
    Join Date
    Oct 2018
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    CA
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    2003 z4
    Yes jman1975...it’s finally done. How life would have been simpler if I knew about the shop that specializes in dme issues sooner. I guess I have to thank the first shop,they were the one who reffered me.

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