GO FISHING, use SLABSAUCE Fishing Attractant
Page 1 of 2 12 LastLast
Results 1 to 10 of 16

Thread: electrical question.

  1. #1
    Join Date
    Nov 2004
    Posts
    205

    Default electrical question.

    my engine dies when i turn on all the electrical components in the car

    at idle, test 9, battery voltage i think
    indicates approximately 13.4-13.6

    when i turn on the aircon, this drops to around
    12.5 - 12.8

    when headlights are on, this drops to 12.1 - 12.2

    when i engage the gear, it goes down to
    11.7 and then, it cuts out...

    i placed a tester on the battery, the results indicate a
    voltage of 13.5 and does not change,

    what could possibly be wrong here?

  2. #2
    Join Date
    Oct 2006
    Location
    Reading, UK
    Posts
    1,853

    Default

    Sounds like your alternator is about to go to the great scrapyard in the sky, it's producing a meagre voltage and not enough current.

    First though, have your battery load checked by someone, if it's on its way out it may produce similar results.

    Could be your wiring/battery terminals though - check those first!

  3. #3
    Join Date
    Nov 2004
    Posts
    205

    Default

    the battery is relatively new

    negative cable from battery is new,
    positive, still have not changed it

    where are the grounding points located?
    i could not find them, i only saw one that is near the battery.

    thanks

  4. #4
    Join Date
    Feb 2006
    Location
    Oldham, England
    Posts
    3,078

    Default Charging voltage

    Mine only gets run about once a week now as I walk to work! So I dont expect the battery to be in great shape. Just checked it out of curiosity and I got these voltage figures on a cold engine:

    Idle: 13.95-14.01
    + A/C (fan has to be on low) and headlights: 13.95-14.01
    + A/C, headlights, heated rear screen: 13.85-13.95
    +A/C, headlights, heated screen, in 'D' (foot on brake): 13.85-13.95

    Looks like the voltage drop you have is killing the motor. I'd be looking at the alternator output as suggested. Some places will check it (and the battery) for free as they want to sell you one! I'd also have a look at the fusible links

  5. #5
    Join Date
    Oct 2006
    Location
    Reading, UK
    Posts
    1,853

    Default

    Quote Originally Posted by whiskychaser View Post
    Mine only gets run about once a week now as I walk to work! So I dont expect the battery to be in great shape. Just checked it out of curiosity and I got these voltage figures on a cold engine:

    Idle: 13.95-14.01
    + A/C (fan has to be on low) and headlights: 13.95-14.01
    + A/C, headlights, heated rear screen: 13.85-13.95
    +A/C, headlights, heated screen, in 'D' (foot on brake): 13.85-13.95

    Looks like the voltage drop you have is killing the motor. I'd be looking at the alternator output as suggested. Some places will check it (and the battery) for free as they want to sell you one! I'd also have a look at the fusible links
    Now you've said that, it could possibly be the engine is idling too low and not spinning the alt faster... is it idling smoothly or is it rough? Do M20's have an adjustable idle air bypass on them, I cant remember?

  6. #6
    Join Date
    May 2004
    Location
    Japan
    Posts
    9,250

    Default

    for my car this helped:

    changed the voltage regulator to a new one, the brushes of the old one were almost gone. Still have some of the good ones from Hella on stock F/S under for sale.
    Fits on Bosch alternators.

    and, also very important: this wire I replaced
    http://twrite.org/shogunnew/fixes/electricalpower.html

    since then no more probs.

  7. #7
    Join Date
    Nov 2004
    Posts
    205

    Default

    without a/c and everything else, im idling at roughly 900-100 rpm...

    then as i start to increase the loads, it starts going down...


    where are all the fusible links that i need to check?

    i changed all the old fuses already, could be loose or something and
    since its cheap... might as well change them...

  8. #8
    Join Date
    Feb 2006
    Location
    Oldham, England
    Posts
    3,078

    Default

    Quote Originally Posted by pong View Post
    without a/c and everything else, im idling at roughly 900-100 rpm...

    then as i start to increase the loads, it starts going down...


    where are all the fusible links that i need to check?

    i changed all the old fuses already, could be loose or something and
    since its cheap... might as well change them...
    Mine only idles at about 700rpm but it certainly does not go down when I switch anything on. In fact, the idle goes up slightly when you put the a/c on - as it should do. It sounds more and more like your alternator isnt giving you the power you need. You can replace the brushes/resistor pack if its faulty. Fusible links are here:
    http://www.bmwe34.net/E34main/Mainte...sible_link.htm

  9. #9
    Join Date
    Oct 2006
    Location
    Reading, UK
    Posts
    1,853

    Default

    Quote Originally Posted by shogun View Post
    for my car this helped:

    changed the voltage regulator to a new one, the brushes of the old one were almost gone. Still have some of the good ones from Hella on stock F/S under for sale.
    Fits on Bosch alternators.

    and, also very important: this wire I replaced
    http://twrite.org/shogunnew/fixes/electricalpower.html

    since then no more probs.
    Hmm, I've heard this may affect E31s too, I shall have to investigate!
    May also be after a regulator from you too, as my alternator doesnt cope well under full load atm.

  10. #10
    Join Date
    Nov 2004
    Posts
    205

    Default

    with regards to the voltage regulator, where exactly is the voltage regulator of and e34, my version has the battery in the front. is it inside the box containing the ecu?

Page 1 of 2 12 LastLast

Similar Threads

  1. electrical socket question
    By h2oyo in forum 5 Series BMW
    Replies: 3
    Last Post: 08-10-2009, 09:49 AM
  2. Radio, CD, Electrical question
    By brodee in forum 5 Series BMW
    Replies: 1
    Last Post: 04-17-2006, 05:06 PM
  3. Electrical question -- Javier?!?
    By Kalevera in forum 5 Series BMW
    Replies: 7
    Last Post: 03-02-2005, 04:53 PM
  4. electrical question,and poll
    By Paul in NZ in forum 5 Series BMW
    Replies: 1
    Last Post: 09-07-2004, 08:15 AM
  5. Rev Limiter Electrical Question
    By DaCan23 in forum 5 Series BMW
    Replies: 0
    Last Post: 05-04-2004, 06:18 PM

Posting Permissions

  • You may not post new threads
  • You may not post replies
  • You may not post attachments
  • You may not edit your posts
  •