adman77
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Registered: 19th Jan 07
User status: Offline
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I'm quite curious to know why my exhaust spits. After some mods to my 8v, 1.4 engine (K&N conical filter, 4x2x1 free flow exhaust, FSE fuel pressure regulator and Iridium plugs, ported and polished head, ported and polished intakes, enlarged and polished throttle body and 270* Piper High lift cam and Magnaflow race series end can), my exhaust has started making spitting sounds. This happens usually after I leave the throttle after revving her medium or hard. Most tuners here say that it's not a bad thing at all and it just shows that your engine is in a good state of tune. I just want to know what actually is the reason behind this. Can you guys please explain?
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DaveB
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Registered: 29th Dec 00
Location: Huddersfield
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too much fuel; most likely due to the fuel regulator. when you've closed the throttle its likely there will still be unburnt fuel in the combustion chambers, when your exhaust valves open this will enter the hot exhaust and pop/bang etc
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adman77
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Registered: 19th Jan 07
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But this used to happen even before I got the fuel pressure regulator installed
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TheCam
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Registered: 16th Mar 07
Location: Kirkcaldy
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Just sounds like your getting a little back fire, as Dave says, its unburnt fuel in the system. I wouldnt worry about it 
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Will_Sport
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Registered: 28th Jun 04
Location: Notts
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my standard corsa does it with a larger back box when its cold and you rev it a bit (like up to 3000rpm in 2nd), then let it go on over run for a bit, it'll pop cos engines tend to run rich when cold.
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Vaux Lad
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Registered: 15th Dec 04
Location: Stoke-on-Trent
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If youve got a cat fitted, i would worry about it.
Its probably the fse regulator making the engine run too rich.
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Superlite Ltd.
Member
Registered: 9th Jan 07
User status: Offline
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Bin the FSE. They change pressure over time with the weather 
With loud popping and spitting you may well be destroying your cat.
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johnhara1
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Registered: 19th Oct 06
Location: Newcastle upon Tyne
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Definately bin that FSE, they're shite!
I quite like the popping and banging my XE Corsa used to make  , that had a stupid FSE on aswell  (Not off me)
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Dave A
USER UNDER INVESTIGATION - DO NOT TRADE
Registered: 10th Dec 03
Location: County Durham
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the fse wont make it overfuel on run down as as soon as the throttle is closed the decel fuel map is lambda controlled. an fse that is incorrectly adjusted will only make a difference to fuelling when the lambda goes open loop at around 3000 rpm and more than 50% throttle.
if an exhaust is spitting its likely to be a missfire.
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DaveB
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Registered: 29th Dec 00
Location: Huddersfield
User status: Offline
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quote:
Originally posted by Dave A
the fse wont make it overfuel on run down as as soon as the throttle is closed the decel fuel map is lambda controlled. an fse that is incorrectly adjusted will only make a difference to fuelling when the lambda goes open loop at around 3000 rpm and more than 50% throttle.
if an exhaust is spitting its likely to be a missfire.
If there is too much fuel when he's driving; that hasn't been burnt - then when the throttle is shut the fuel is STILL in the combustion chamber with nowhere go except out through the exhaust manifold
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Huwsi
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Registered: 27th Apr 07
Location: Bangor, Gwynedd
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I bet you enjoy it really 
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adman77
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Registered: 19th Jan 07
User status: Offline
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Yes I do. I really do.
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gsirick
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Registered: 18th Feb 07
Location: mid-wales
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my saxo vtr used to pop and backfire but that had a 3" straight from down pipe to a 6" backbox, u could of classed it as a flame thrower lol
does your corsa have a cat?
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Dave A
USER UNDER INVESTIGATION - DO NOT TRADE
Registered: 10th Dec 03
Location: County Durham
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quote:
Originally posted by DaveB
quote:
Originally posted by Dave A
the fse wont make it overfuel on run down as as soon as the throttle is closed the decel fuel map is lambda controlled. an fse that is incorrectly adjusted will only make a difference to fuelling when the lambda goes open loop at around 3000 rpm and more than 50% throttle.
if an exhaust is spitting its likely to be a missfire.
If there is too much fuel when he's driving; that hasn't been burnt - then when the throttle is shut the fuel is STILL in the combustion chamber with nowhere go except out through the exhaust manifold
do you know how fast combustion happens I wont go into the technical side of your reply but it judt doesnt work that way.
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adman77
Member
Registered: 19th Jan 07
User status: Offline
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quote:
Originally posted by gsirick
does your corsa have a cat?
Nope. It's a straight pipe.
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