Opel Coras Utility 2001 1.6i pre-igniting

[Ralph_R]

Hello
I'm new on this forum and I'm hoping that someone can help- I have a 2001 Opel Corsa Utility bakkie 1.6i Sport. the bakkie is very nice and when I bought it in Dec 2016 I serviced, replaced cam pully and belt, let the time set and all the good things. the problem I have is when I switch it off it from time to time pre-ignite -or backfire - whatever the right expression is) (but not all the time) I have now replaced Ignition coil, Bougie chords and plugs but the problem is still there
any takers to guide me in the right direction?

Thanks
Ralph

[EvanTate]

Does it over heat at all?

Take the plugs out and see if it's not maybe running too lean (white plugs) which could cause a bit of detonation in residual fuel once the ignition has been turned off.

It could be anything from a lean mixture to bad timing.

Was it doing this before the service?

[Ralph_R]

Yep it started soon after I bought it - might have been an old problem as I said it is not doing it all the time
well I've taken out the "old" 2000km plugs and replaced it with new ones
will probably have to take it to Opel for a check

[8 Valves of glory]

Have you checked the crank gear? might be the keyway thats worn and now timing is out. It's a common thing on corsa's. I've just done mine again but this time with a bit of a modification to prevent it from ever happening again.

Does the bakkie feel slightly sluggish when pulling away as well? and fuel consumption a bit more than before?

[8 Valves of glory]

don't know why i'm only responding now lol