13 replies to this topic

[Mini Tom]

I keep getting back firing every now and then. Bascially i double de-clutch all the time and some times when i tap the gas peddle whilst in neutral every now and then there will be a bang out of the exhaust. Is this fuel over running and then igniting on the hot exhaust? Is it a major problem? Is it causing any damage to my car?
Cheers
Tom

[pikey7]

It isn't doing it any good. Possibly a timing issue. Do you have any other problems? High fuel consumption, running on, pinking etc etc.....

[Guess-Works.com]

I hate to say, that mines doing it all the time, but it's just down to needing the engine tuned... mixtures and timing set...

[Bungle]

baby bungle back fires a lot as well, :'( i put it down to the fuel we feed him

[mambaman]

often its cause by a leaky exhaust which is taking in air which is then combusting with unburnt fuel in the exhaust gasses. Its only usually exposed when the engines running rich, or on over-run. Check the exhaust by blocking it with the engine idling, your hand over the end should surfice, you should hear air escaping which indicates a leak.

[jif2006]

Dam wish mine would backfire

[Mini Tom]

umm my fuel consumption isnt that great. its 1275 and i get through a tenner a week in fuel and i spose i drive about 20 - 30 miles a week if that. i put shell fuel in it dunno whether this makes a difference or not. i don notice that with shell fuel my exhaust sounds far beefeier than BP or sainsburys etc. cheers for the help

[Steamo]

That would mean around 10-15 MPG and thats shocking, probably running really rich.

[pikey7]

deffo sounds like it is in dire need of a tuneup.

[Mini Tom]

yeah i suppose it wouldnt hurt to get it tuned. Does anyone know of how much this would cost roughly? Is it expensive because I'm only 18 and get paid rubbish amounts.
cheers

[pikey7]

prob around the £60 mark. see the rolling road thread in minichat

[Mini Tom]

wicked cheers mate

[Cartera619]

dunno if you're still having the problem but my car was doing the same thing after an engine conversion. Went through all the usual causes, air leaks, timing and mixture even changed the carb.

We discovered it was a faulty ignition module on the electronic ignition now she runs sweet as.

hope this helps someone with similar problems.

[Sprocket]

Burble is aparent when cat is removed and single straight through box fitted. Its fuel being fed back in after the revs reach the lower limit of over run fuel cut. Lots of oxygen in exhaust as on over run there is no fuel, the engine just becomes an air pump, Lambda sensor sees a lean mix, over compensates on fuel feed in and resulting in a sort of minor backfire(burble) in exhaust for short period.

Other causes are leaky exhausts or over fueling. Leaky exhaust are not good for emissions tests as more oxygen pressent, also if its before the cat and its still fitted, the cat will overheat. Over fueling is a sensor issue and noted by black sooty plugs.