Omega Owners Forum
Omega Help Area => Omega General Help => Topic started by: gsizoli on 04 February 2009, 16:25:19
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Hi!
This quetion is addressed for mechanics.
Does anybody know what is the real function of the secondary air injection system?
As I know it's heating the cats till the operating tempearture is reached, (By feeding air into the exhaust manifold (secondary air), CO and HC are oxidized through afterburning at temperatures over 600°C to form water and carbon dioxide. The exothermal reaction also increases the exhaust gas temperature, which warms the catalyist more quickly.
) but a guy says it'"s not heating (it's heated by the exhaust gas) just blows air which mixes with the exhaust gas to protect cats from damage.
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i dunno what they do, but many people take them out and notice no difference
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its to fast warm your cats to keep emmisions down ! was only for banding at the time :y
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The secondary air injection is a system where by air is blown into the exhaust manifolds for the first few minutes of startup, any unburnt fuel then ignites in the front pieps and the cats heat up a bit quicker.
This is done by a large blower which is mounted in the passenger side front wing, the air blows through a tube into the vac operated shut off valve mounted on the radiator (vac operated so when at Wide Open Throttle there is no air injection plus there is ECU control to via a vac valve).
Courtesy of Marks DTM Oct, 2006
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its only purpose is to make people post questions on here about "whats that horrible noise, whats it for, how do i get rid?" so all can give a unanimous reply.... Unplug it! Thats all it does. :-)
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Usual use more energy to create less emmisions 'dangle berries'
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And what's wrong about reducing the CO and HC emissions?
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And what's wrong about reducing the CO and HC emissions?
It doesn't reduce CO(x) or HC though. It reduces NO(x)
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And what's wrong about reducing the CO and HC emissions?
It doesn't reduce CO(x) or HC though. It reduces NO(x)
Reducing CO and HC requires oxidizing conditions (as made by the secondary air). Reducing NOx requires reducing conditions (as made during the rich cycles at closed loop).
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And what's wrong about reducing the CO and HC emissions?
It doesn't reduce CO(x) or HC though. It reduces NO(x)
Reducing CO and HC requires oxidizing conditions (as made by the secondary air). Reducing NOx requires reducing conditions (as made during the rich cycles at closed loop).
Actually, you're right - my mistake for not reading the question fully before reading...
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But to answer your Q, it doesn't really help enough with emissions to make it worthwhile. Its removed from later UK spec cars.
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AFAIK, at least the 2.2 hasn't got it. I'm a bit curious what replaced it though. Better engine management, or some pre-cat on the down tube or something?
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AFAIK, at least the 2.2 hasn't got it. I'm a bit curious what replaced it though. Better engine management, or some pre-cat on the down tube or something?
nothing replaced it.
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Well, it was required to pass Euro2 emissions, so I guess something was done to still pass the later Euro emission codes.
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Well, it was required to pass Euro2 emissions, so I guess something was done to still pass the later Euro emission codes.
yep went twin cats and dbw throttle and cpp :y
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Well, it was required to pass Euro2 emissions, so I guess something was done to still pass the later Euro emission codes.
yep went twin cats and dbw throttle and cpp :y
None of those would affect emmissions....
Any improvement in emmissions must be done on the management side, though NOX reduced by lower compression ratio (rather than EGR)
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AFAIK, at least the 2.2 hasn't got it. I'm a bit curious what replaced it though. Better engine management, or some pre-cat on the down tube or something?
Correct, small pre-cats......these heat up much faster and hence no air injection......just an emission light that comes on when the pre-cats get tired!
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And what's wrong about reducing the CO and HC emissions?
At the cost of more pollution making the kit, extra energy to drive it, extra fuel to carry it around - I reckon it is a waste
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afaik, there was a proposal to introduce a new emissions requirement where the total emissions from key-turn through a simulated urban drive was to be capured and measured but pressure from the US got it blocked.
In response, Vx fitted the secondary air injection to the Omega which would reduce HC emissions by oxidising (burning) unburnt fuel in the manifold and down pipes and help the cats get to operating temperature more quickly.
Ford and Jaguar were both experimenting with massive 3-phase (AC) alternators on engines at Nottingham University, the alternators would put the engines under load to promote rapid warm-up and the electrical power was dumped into oil and water heaters (and on the diseasle Jags they had electric cabin heaters). I think the alternator fitted to the V6 diseasle was 100kW.
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And what's wrong about reducing the CO and HC emissions?
At the cost of more pollution making the kit, extra energy to drive it, extra fuel to carry it around - I reckon it is a waste
Can you give a ball park estimate of the extra energy consumption and relate that energy consumption to the benefits of having cleaner air in a city centre? My second car (a mazda 323) doesn't have a secondary air system, and it's a huge difference between the two cars how fast the cats starts working.
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And what's wrong about reducing the CO and HC emissions?
At the cost of more pollution making the kit, extra energy to drive it, extra fuel to carry it around - I reckon it is a waste
Can you give a ball park estimate of the extra energy consumption and relate that energy consumption to the benefits of having cleaner air in a city centre? My second car (a mazda 323) doesn't have a secondary air system, and it's a huge difference between the two cars how fast the cats starts working.
My 2.6 doesn't have SAI, I think that says a lot
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It says that the SAI's function has been replaced by something else. There's a big difference between replacing and removing.
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It says that the SAI's function has been replaced by something else. There's a big difference between replacing and removing.
Nope any effect it had is now managed by the ECU
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That's exactly what I meant. So when removing it from a car that had it fitted, the effect is gone->higher emissions.
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Well, it was required to pass Euro2 emissions, so I guess something was done to still pass the later Euro emission codes.
Our government put the price of fuel up so high that none of us could afford to drive!!! Less emissions ;)
Wwll done Mr Brown :-X