generic efi/tacho question
  • Help
Results 1 to 3 of 3
  1. #1
    1000+ Posts jo proffi's Avatar
    Join Date
    May 2003
    Location
    sydney
    Posts
    8,496

    Default generic efi/tacho question

    Hello brainstrust.
    I have a question of a generic nature pertaining to efi/tacho dash gauge.

    The neighbour has a fairweather friend who has a habit of dumping his POS beemer 6 series coupe in the shed at the worst possible times. This time it was over christmas and the bitch would not start either so we had to push it around by hand.

    Advertisement


    Anyway, on the 'not starting' thing, the owner worked out there was no spark. I confirmed this with a timing light.

    I also noticed that there was no tacho needle twitching when cranking the beast.

    This had me thinking that maybe the ecu was not getting a crank angle reading, and not triggering the coil or the dash gauge.
    Does this logic sound correct or does the tacho needle not moving, prove nothing????

    If it wasn't such a cluttered engine bay I'd have attempted to clean the TDC sensor and retry cranking, but its hot, the owner is not my friend, and my care factor ran low.

    I'm still curious about my logic though, should the tacho needle move during cranking???


    Jo

  2. #2
    1000+ Posts PeterT's Avatar
    Join Date
    Jul 2000
    Location
    Castle Hill, Sydney
    Posts
    7,568

    Default

    If you know how the tacho gets its pulse you can certainly use for fault finding:

    Case 1: Tacho gets 12V square wave from ECU - if nothing when cranking then most likely crank position sensor

    Case 2 : Tacho gets pulse from coil - if nothing, could be either faulty coil, ignitor, ECU or cps.

    '92 205 Mi16
    '90 Mi16x4

  3. #3
    1000+ Posts jo proffi's Avatar
    Join Date
    May 2003
    Location
    sydney
    Posts
    8,496

    Default

    Thanks Peter.

    Jo

Thread Information

Users Browsing this Thread

There are currently 1 users browsing this thread. (0 members and 1 guests)

Posting Permissions

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