Intermittant Engine fault on Vauxhaul Astra

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