Exhaust Backfire - Advice needed please

Hi,
new member here

i just bought a 1994 V8 ES with LPG as the new family car, but it had a few problems.

the exhaust middle box had a crack in it which was causing a hell of alot of noise. so i decided to get it changes.

went to kwik-fit and they said they wouldnt fit any because they can only supply one make which they know causes problems and explodes.

so i went to a local exhaust place, paid £220 and they fitted a new middle & rear box.

Drove 5 miles, then startes hearing some popping sounds, stopped looked under the car and heared backfiring from the middle box which looked like it was gonna explode.

Went back 2 the place and theu said its because the car was overfueling.

Now, when i asked what make the exhaust they fitted it was the same one kwik-fit would supply.

it wasnt backfiring with the old cracked box.. but im worried now as i dont know who to believe.

Has anyone had any experiences with these boxes, could the original LR box fix this prob.??

Please help as i need to sort this car on monday.

Thanks Guys

Wouldn't like to say for sure but if it has been over fueling it is a possibility you may have Cat trouble as over fueling soon takes them out and can lead to excessive back pressure build up. Get a Co reading from your local garage ( give em a drink ) and that will tell you whats happening. If they are gone and you fancy a laugh get a quote for replacement from a landrover dealer ( sit down first) £800 - £1000, I did get a qoute for mine which worked out at £120 plus post for the pair, but the quality is unverified as I have not ordered them yet, but at that price I am prepared to chance it, good luck

If it backfires on the overrun it normally means you have an air leak somewhere so check they fitted the box properly with exhaust goo.

so no-ones had any problems with cheapish exhaust boxes??

if it is overfuling how easy is it to turn down??

thanks

very rare to have a problem with non landrover exhausts. you should get co checked to see if it is rich before trying to find a fault. Any number of reasons for over fueling although the o2 sensor should pick this up and if it could not control it it would go open loop and the computer would take over sensors job. A faulty injector is a good cause.

disco mart & Walter, ill go and get a co2 reading today. Jim, the exhaust seems like the best ive ever seen fitted, goo and all was used.

Today though i notices that the backfiring has calmed down, and now only seems to backfire very very quietly and also very rarely.
but my idle has messed up, whilst in Drive, the car goes to around 250 rpm, which almost kills the engine, if im in neutral it jumps between 250-1000rpm constantly, causing the car to shake like hell.

thanks for ur help guys,