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Backfiring Slightly & Big Hole In Start Of Exhaust?


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Changed plugs & leads successfully yesterday & now unless it's my imagination actually sounds even worse now althou my mechanically retarded ear isnt sure if it's still a misfire or just the loud noise coming from having a nice big hole in the exhaust (not sure of the technical terms, downpipe? as it's just where the join is as exhaust comes down from erngine bay before leveling out?) + it seems like that long ago when i last used her, ok only a week, but think it maybe just cause i didn't notice before cause it's so quiet inside with doors & windows shut

When i took her for a drive yesterday she was certainly popping a bit from the rear of the exhaust, would that be a result of the ropey exhaust, knackered cat or more likely still something more awry with the engine itself?

Pulled smoothly enough, zaust noise aside, although i certainly wouldn't say she was on full power.

I know it's hard to diagnose without hearing it or at least a better explanation & think i will take it somewhere to see what they think anyways but thought i'd see if anyone had any thoughts on best worst or otherwise case?

I recall there's no real aftermarket exhaust for LS400 so presuming i just get powerflow to make one do i have to get a cat put back in as a 1993 or can i get away without one legally speaking? although i do know a friendly MOT man who used to get me decatted RX7 through nudge budge ;) lol.

Ta

Si (hoping it's nothing too major as my confidence on working on the lex is growing after changing plugs seemed to go OK......)

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The backfiring will be the hole in the exhaust - unburnt fuel in the exhaust (especially on the overrun) then gets access to oxygen which makes it burn in the pipe. And it certainly won't do the cat any good, the burning fuel will make it overheat... Also the lack of backpressure in the exhaust will affect the cylinder pressures, which may also be the cause of your power loss.

Unfortunately getting it fixed is the only option, though I don't think changing the plugs and leads will have made any difference to your problem.

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cheers that is reassuring to some degree :D

Going to take it into powerflow tomorrow for a nice healthy quote on twin twin full system & might as well replace cats, since i will need them. On that note actually anyone know how to check when engine is dated? Car is late 93 but i guess it takes many months to build ship etc etc so being optimistic i might be able to prove engine is pre aug 02 or whenever it needs to be to avoid emissions, wont hold me breathe thou.....

Stuck a load of exhaust filler/repair putty stuff over hole just to make a desperate attempt for short term fix & notably someone had tried to do same before & looks like on the other downpipe, if thats correct phrase still, as well so probably just fell off recently, either way i smell some stainless steel credit card abuse around the corner.....lol

Ta

Si

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  • 2 weeks later...

well i spent nearly as much on exhaust as i did initially buying car although it does sound a lot better, i'll get some pictures up when i have a poke round me back end, so to speak :o lol

Didnt solve all the issues but no more backfiring at least.............

Si

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