Intermittant Engine fault on Vauxhaul Astra

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

regards

Dave

 

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

mike

 

faulty fuel relay?

 

Without further information, I'd say the most likely culprit is the ignition
amplifier module.

 

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
faults.

 

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.

HTH

Anthony
Remove eight from email to reply.

 

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

 

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.

regards

Dave

 

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
ohms.

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,
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.

 

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.

regards

Dave

 

With pleasure

regards
Dave

 

Thanks