over running and back firing on turn off

[T_J_G]

Some times my car does this ('91 1.8 Driver carb) mainly after i've been giving it a lot of stick. Doesn't always backfire though, but when it does it shoots out a big flame from my exhaust.

Which is dangerous and probably f**king the exhaust up.

I've heard this may be the exhaust manifold gasket? Possible?

I may buy a GTi manifold (any power increase?) and i'm after a new exhaust system anyway.

any ideas people?

Cheers
Tim

[lch1]

over running is usaully caused by a igntion timing fault  have you had the belt changed recently or may have slipped highly unlikely though as you would have known alright!!!
could be a air leak on fueling, knackered gaskets on inlets probably the answer cant see how it could exhaust gasket whip out your plugs and have look at bottom of plugs if the is loads of carbon on them (loads of black sooty s*** on the base of them0 it is over fueling
 does it run hot ?? 

[T_J_G]

I had the inlet manifold off to replace the coolant 'o' ring about a week ago. Problem was there boefore.

I've recently just out new spark plugs into it aswell, i may whip one out and have a look.

It runs just under half temperature.

And is very juddery when starting from cold.

I guess i need to sort the ignition timing out then.

[lch1]

good idea check timing after your plugs as these are a lot eaiser
let us know how u get on mate
regards lch1

[T_J_G]

I've absoloutely no idea how to do the timing.

 

[lch1]

could sit here and type out but would be here most of the day and if you messed it up valves meet piston, piston meet valves alas no more engine  it is all to do with lining up marks on crank and camshaft finding TDC (top dead center)of pistons travel up the bore and alignment you can advance or retard your distributor but best not touch again if you dont know what you are doing mate take it to someone who does it is easy if you know but had to have someone show me twice before i attempted my self

[T_J_G]

i've just read up on it in my Haynes Manual and will probably call someone out to do it (these mobile tuning companies) or take it to where my mate woks. Or possibly see if my Dad understand any of it.

Thanks for your help!

[lch1]

if you have got a haynes follow it word for word take your time and you will be fine but dont RUSH IT !!!! it is easy honest just have confidence (GOD!!! I SOUND OLD!!!!)

[T_J_G]

I think i will wait till tomorow when my Dad is around. That way what i don't understand he will. Again thanks for your help much appreciated.

[rubjonny]

dont worry about getting it wrong, the 8v is a non interfearance engine.  Worst you'll do is make it run crap
I had problems with overrun, and tracked it down to the idle overrun valve on the back of the carb, its the metal square jobber with an electrical connection.  I just replaced it with a non-rusty one and all was well when stoppin the car once more.

I also had trouble in the summer, and it turned out the slow speed on my radiator fan was buggered so it was getting a bit hot, that combined with excessive carbon build up in the cylinder due to autochoke problems caused hot spots in the cylinder.

I sprayed half a tin of carb cleaner down the inlet whilst reving the engine, and it soon cleaned all that crap out