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Thread: m30b34 swapped E30 very hard to start when cold?

  1. #1
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    m30b34 swapped E30 very hard to start when cold?

    im not sure if this is the best section to post about this since e30s never had m30 originally but I have a little problem since it's about -20 celcius in finland at the moment and its a bitch to get my m30 started, it will start after cranking it for ages and usually the battery runs out of charge before it will start. once it does start up it runs completely fine no problem whatsoever it will idle at high rpm for a while and eventually drop to around 600. so any ideas what could be the issue? could it be that the cold start valve is working improperly? however the cold start valve is put in a place that is almost impossible to get to without taking whole intake manifold off
    Last edited by Jalmarsson666; 02-24-2018 at 10:00 AM.

  2. #2
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    coolant temp sensor, idle control valve, afm, throttle position switch, and miles of leaky vacuum hose are also suspect in a cold / hard start situation. all of which are a bit easier to get at and test. what are you running for an ecu ? are you motronic 1.0 or 1.1, or possibly 1.3 ? i can't imagine you're running a jetronic but i guess it could be swapped in, if so an aux air slide could be present as well. europe had loads more variants than we got in north america so it's a bit hard to figger with the info you included.

  3. #3
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    Quote Originally Posted by 82eye View Post
    coolant temp sensor, idle control valve, afm, throttle position switch, and miles of leaky vacuum hose are also suspect in a cold / hard start situation. all of which are a bit easier to get at and test. what are you running for an ecu ? are you motronic 1.0 or 1.1, or possibly 1.3 ? i can't imagine you're running a jetronic but i guess it could be swapped in, if so an aux air slide could be present as well. europe had loads more variants than we got in north america so it's a bit hard to figger with the info you included.
    well I haven't done the swap myself so I can't be sure which it is but I assume it's 1.3 since there is the ability to read codes, and when the car is hot it sometimes differs how it will start, sometimes it will start almost immeaditely as it cranks and sometimes it has to crank for about 2-3 seconds when hot before starting, also there is a slight sputter from the exhaust on idle but it's quite un noticable. do you have any idea where I can find any guides on how to test these parts you mentioned are working?

  4. #4
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    323i E30 is offline ⅂!ʈө !ƨ l!ʞө ɐ ʇөlөbµouө
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    Quote Originally Posted by Jalmarsson666 View Post
    (...) e30s never had m30 originally (...)
    Don’t forget about the South African E30 ‘M3’..
    ^ true story



    D̶i̶b̶s̶ ̶o̶n̶ ̶t̶h̶e̶ ̶E̶2̶1̶

  5. #5
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    Grounded the black/red wire that is connected to thermo time switch, that should make the cold start valve open during startup but it did not help at all

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    Loud buzzing noise from the fuel pressure regulator, is it supposed to have that?

  7. #7
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    Now i cant get it started at all, recharged battery 4 times and cant get it to start. Sometimes it will almost start but doesnt, tried to give the cold start valve Directly 12volts to force it open while cranking but that did not help either. I assume its not getting enough fuel when cranking? But how come it runs perfectly fine IF it starts..im pretty confused since this hasnt happened to me before

  8. #8
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    #1 thing is to determine what was swapped in and get a bentley for a car with that version of the m30b34 and ecu combo. without it you are just spitting into the dark. it will walk thru the tests you need.

    to check your cold start valve :

    make sure engine temp is below 30 degrees celcius
    remove the two hex screws holding the cold start valve to the intake manifold
    pull cold start valve from the manifold but leave everything else connected
    disable ignition system - unplug coil -
    wipe valve dry and point it into a glass or clear plastic container
    have a helper turn the car over by turning ignition key


    -valve should spray in an even cone shaped pattern for ~ 8 seconds until the thermo time switch cuts it off
    -if spray pattern uneven or intermittent the cold start valve is faulty
    -if no spray at all then thermo time switch is faulty or both may be faulty

    wipe cold start nozzle immediately after test

    -if valve drips within 1 - 2 minutes then it is faulty. cold start valve should remain dry.


    that will narrow it down.

    good luck and pick up a bentley.

  9. #9
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    Ill test the csv on weekend once i have time.

    Now the weirdest thing happened yesterday, I tried to start the car after it had sat for about 5 hours and could NOT get it to start so i give up and go inside, then about 3-4 hours later i go out and try again and it starts IMMEDEATELY? How is it even possible it fired right up as soon as i twisted the key when it has never done this before no matter how much i primed the pump or tried to crank it? Confused.

  10. #10
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    https://youtu.be/RaWIKlXqR8c

    Relatively warm engine takes this long to start aswell..

  11. #11
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    Did you already check the basics to make sure it's not fuel related ? Check fuel pressure after car sat for sometime and you first crank it

  12. #12
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    Sadly i dont own a Fuel pressure check gauge but i ordered a fuel pressure regulator with a fuel pressure gauge attached to it, is it a valid way to check if the car holds pressure on the fpr gauge?

  13. #13
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    Changed fpr but it doesnt start at all with the adjustable one, it shows pressure with key in on and as soon as you crank it drops to 0

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