Intermittant Engine fault on Vauxhaul Astra

Discussion in 'Astra' started by Dave Morgan, Dec 6, 2003.

  1. Dave Morgan

    Dave Morgan Guest

    Hello All

    Can anyone pass comment on the following fault on an Vauxhall Astra L
    reg model fitted with C 14 NZ engine as follows:-

    Engine cuts out intermittent for no apparent reason after short run
    and cannot be re-started for about 5- 10 mminutes after fault appears.
    Tests carried out reveal that during fault presence no spark is being
    seen at plugs. Examination with a Gunson code fault reader indicates
    code 12 on dashboard which is the engine normal code indicating
    engine is without problem despite fault. Battery voltage is also
    present at ignition LT coil plug.

    Any comments greatly appreciated, many thanks


    Dave Morgan, Dec 6, 2003
  2. Dave Morgan

    mike Guest

    distributor cap, rotor arm, points, points suppression capacitor, ht leads,
    faulty lamination in ht coil,
    i'd go with removing the capacitor first.

    mike, Dec 6, 2003
  3. Dave Morgan

    Stuart Gray Guest

    faulty fuel relay?
    Stuart Gray, Dec 6, 2003
  4. Dave Morgan

    malcolm Guest

    Without further information, I'd say the most likely culprit is the ignition
    amplifier module.
    malcolm, Dec 6, 2003
  5. Dave Morgan

    Dave Plowman Guest

    The easiest test of even a modern ignition system when there's no spark is
    with a dwell meter - it should give approximately the same reading as with
    a points set up. If not, you're looking at the trigger or amp module. The
    trigger will usually fail open circuit, so some types can be tested with a
    DVM for continuity or to look for a pulse output.

    This is only general as I don't know the engine, but if it has a separate
    ignition amplifier this would be favourite as they often have intermittent
    Dave Plowman, Dec 6, 2003
  6. It is either the ignition amplifier module, which is mounted below the
    ignition coil, or the pulse generator in the distributor. The amplifier is
    the more common culprit. Check the 3pin connector going into the bottom of
    the distributor for corroded or loose connections first though.


    Remove eight from email to reply.
    Anthony Britt, Dec 6, 2003
  7. Dave Morgan

    MrCheerful Guest

    I just spent ages fixing this on a corsa, I found that by tweaking the
    connector to the distributor the spark returned and the car would go again.
    I cleaned the connector and even cabletied it , but the problem kept
    reurning. Eventually I went to a breakers and bought another ditributor and
    cut the lead off with it, soldered the lead together on the car, including
    repairing the shielding using silver foil. Touch wood, the car has gone
    ever since.

    MrCheerful, Dec 6, 2003
  8. Dave Morgan

    Dave Morgan Guest

    Many thanks to all who have commented on fault which confirms
    suspicion of int. Amplifier module failure.

    However, would anyone know if I could pulse the amp module (in fault
    mode) via a series current limiting resistor from the 12 volt battery
    supply (Engine Management Unit of course disconnected from amp module)
    to generate a spark at plug. Maybe a bit technical but would serve to
    eliminate distributor pulse coil as mentioned above.

    Would anyone know what the typical input trigger voltage/current is to
    trigger the amp so I can work out series resister value and power
    rating to amps input.

    Once again, thanks for useful advice.


    Dave Morgan, Dec 7, 2003
  9. Dave Morgan

    Dave Plowman Guest

    Easier to eliminate the pulse coil surely? Unless it's some fancy solid
    state device it can be measured with a DVM. Coils usually fail open
    circuit. The one on mine (not Vauxhall) has a resistance of approx 1000

    Another way to check for primary operation is to wire a mains neon across
    the +/- terminals of the coil. It should flash when the engine is turned.
    Dave Plowman, Dec 7, 2003
  10. Dave Morgan

    Exarkun Guest

    I have the same engine in my Nova. (C14NZ). Sounds very much like the
    problems that I'm having. If you happen to solve this, will you please tell
    me what you finally did to fix it.
    Exarkun, Dec 8, 2003
  11. Dave Morgan

    Dave Morgan Guest

    Thanks for comment, sometimes I have a nasty habit of thinking too
    complex at times due to the electronics I have to fill my brain with
    these days.

    The connection of a neon is most interesting and one assumes that its
    the back EMF genreated by the coil when ignition amp open circuits
    the induced coil current that allows the mains neon to flash assuming
    the coil not o/c'd. Question, if one disconnected amp module from
    coil, breify shorted coil's LT side to vehicle ground with +12v
    present at its hot end would neon still emit single pulse to show LT
    coil integrity when this fault appears. Migh have some uses this
    method as well the normal DVM voltage, continuity checks.

    Anyhow, many thanks for comment will try this method.


    Dave Morgan, Dec 9, 2003
  12. Dave Morgan

    Dave Morgan Guest

    With pleasure

    Dave Morgan, Dec 9, 2003
  13. Dave Morgan

    Exarkun Guest

    Exarkun, Dec 9, 2003
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