Omega Owners Forum
Omega Help Area => Omega General Help => Topic started by: turbonuts on 11 February 2007, 18:02:37
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hi there i have a 97 2.0 16 valve omega and when i start it when its cold the engine makes a loud wigning noise from the front passenger side if anyone can help me out that would be greatfull :y
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hi there i have a 97 2.0 16 valve omega and when i start it when its cold the engine makes a loud wigning noise from the front passenger side if anyone can help me out that would be greatfull :y
It is probably the secondary air injection pump that runs for few seconds to warm up the cats and reduce emissions. Nothing to worry about mate.
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well thanks for that mate a friend said that the cold start and it cost 500 pound to fix but i thorght i would ask the blokes in the know thanks again mate
:y :y :y :y :y
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unplug the pump, see if the noise stops ;)
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A genuine new pump is £350+VAT.
But they do nothing useful and even Vauxhall dropped them from newer models. As TB says unplug it and forget it.
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...even Vauxhall dropped them from newer models...
Everyone seem to be saying that.... :o
But in the 2001 sales brochure describing the 2.6/3.2 engines they say:
'Emission control: Electronic exhaust recirculation. Secondary air injection. Activated charcoal evaporation control canister. Lambda sensor and twin three-way closed-loop catalytic converters.'
So it seems that the EGR function is still there though it is now electronic i.e. without the machnical EGR valve, and that the secondary air injection pump is still somewhere in the system...? :-?
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...even Vauxhall dropped them from newer models...
Everyone seem to be saying that.... :o
But in the 2001 sales brochure describing the 2.6/3.2 engines they say:
'Emission control: Electronic exhaust recirculation. Secondary air injection. Activated charcoal evaporation control canister. Lambda sensor and twin three-way closed-loop catalytic converters.'
So it seems that the EGR function is still there though it is now electronic i.e. without the machnical EGR valve, and that the secondary air injection pump is still somewhere in the system...? :-?
No, those parts no longer exist. The lower compression ratio means no need for EGR, as little NOX anyway...
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...even Vauxhall dropped them from newer models...
Everyone seem to be saying that.... :o
But in the 2001 sales brochure describing the 2.6/3.2 engines they say:
'Emission control: Electronic exhaust recirculation. Secondary air injection. Activated charcoal evaporation control canister. Lambda sensor and twin three-way closed-loop catalytic converters.'
So it seems that the EGR function is still there though it is now electronic i.e. without the machnical EGR valve, and that the secondary air injection pump is still somewhere in the system...? :-?
No, those parts no longer exist. The lower compression ratio means no need for EGR, as little NOX anyway...
..but the sales brochure... it says.... :-/
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thank you for the replys and where do i un plug it wat do i need to look for
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thank you for the replys and where do i un plug it wat do i need to look for
Between bumper and NS Front wheel, look up under there, there will be a pump. Just unplug it...
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It's above the horns and about the size of a small football.
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No, those parts no longer exist. The lower compression ratio means no need for EGR, as little NOX anyway...
Sorry to hijack the thread, are you (or VX) saying that lower compression ratios result in lower NOX?
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According to http://www.autozine.org/technical_school/engine/petrol2.htm, this is what the EGR does:
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Exhaust Gas Recirculation (EGR)
Exhaust Gas Recirculation is a proven technique to reduce fuel consumption and emission. It does that by recirculating some of the exhaust gas back to the combustion chamber. Thus the effective engine displacement is reduced and drink less fuel. Inevitably, you may say this also reduce power output, so why not select higher gear and slow down the engine to obtain the same result ?
The answer is: not every one like this kind of cruising. If you drive in a hurry, you don’t like to reduce the engine speed as you want to accelerate as soon as overtaking opportunity comes. If you drive in traffic, which calls for intermittent acceleration and deceleration, you are not likely to select the 4th and 5th gear too. A considerable large portion of our daily driving is spent on the "low gear, high rev" pattern which does not optimize fuel consumption. This makes EGR worthy.
EGR recirculate some of the exhaust gas (probably up to 10%) back to the inlet valve via a recirculation pipe. The amount is determined by engine ECU and controlled by a valve at the recirculation pipe. When the ECU believes the engine is running at light load, it directs the exhaust gas back to the combustion chamber. As the exhaust gas is largely non-ignitable and takes no part in the combustion process, the fuel injection can emit less fuel without worrying failure combustion. As a result, the engine still run at roughly the same speed but power output, fuel consumption and emission are all reduced.
Yet this is only half of the story. Another large portion of the fuel and emission saved is contributed by the reduction of pumping loss. Pumping loss is the power used to pump the fresh air into the cylinder and pump the exhaust gas out, of course the "pump" is the piston. To reduce the power wasted in pumping in fresh air, we can pressurised the input air, that is, using turbocharger, or alternatively add some high-pressure, speedy gas into the input stream. In our case of EGR such gas is the exhaust gas.
To our environment, apart from the emission reduced via consuming less fuel, EGR also reduces NOx emission. How ? as the amount of combustible gas is reduced, temperature in combustion chamber is also reduced. Because NOx generates at high temperature, NOx emission is also reduced.
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Also, form the same source:
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Lower compression ratio means less energy loss in compressing air, i.e., the so-called "pumping loss". Moreover, lighter compression leads to lower temperature, thus reduces heat loss in cylinder wall and pistons. To compensate the reduction in real capacity, a supercharger is employed to increase the air density such that the engine actually resume 100% capacity. Of course, the supercharger must generates less pumping loss than those gain by reducing compression ratio.
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...even Vauxhall dropped them from newer models...
Everyone seem to be saying that.... :o
But in the 2001 sales brochure describing the 2.6/3.2 engines they say:
'Emission control: Electronic exhaust recirculation. Secondary air injection. Activated charcoal evaporation control canister. Lambda sensor and twin three-way closed-loop catalytic converters.'
So it seems that the EGR function is still there though it is now electronic i.e. without the machnical EGR valve, and that the secondary air injection pump is still somewhere in the system...? :-?
Just for informatiom, you do not need an EGR valve to introduce EGR to an engine, you can allow exhaust gas recirculation with a certain amount of valve overlap(it is called internal EGR) You could go up to 40% EGR like that.
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So putting one and one together, it seems that:
Lower compression = lower combustion temperatures = less NOx
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No, those parts no longer exist. The lower compression ratio means no need for EGR, as little NOX anyway...
Sorry to hijack the thread, are you (or VX) saying that lower compression ratios result in lower NOX?
Anything that cause the combustion peak flame temperature to exceed 2700 degreen Kelvin will result to NOx formation. As Markjay says below the lower compression reduces it.
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Just for informatiom, you do not need an EGR valve to introduce EGR to an engine, you can allow exhaust gas recirculation with a certain amount of valve overlap(it is called internal EGR) You could go up to 40% EGR like that.
Although to do this effectively you need a full VVT setup....
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Just for informatiom, you do not need an EGR valve to introduce EGR to an engine, you can allow exhaust gas recirculation with a certain amount of valve overlap(it is called internal EGR) You could go up to 40% EGR like that.
Although to do this effectively you need a full VVT setup....
Indeed!
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This is interesting, but I think that if you rely on the intake stroke of the piston to suck exhaust gasses back into the chamber then you will have serious gas flow issues in the exhaust manifold? The traditional EGR system seems to minimise this sort of unwanted turbulence by taking the exhaust gasses out of the combustion chamber with the gas flow and then introducing them back into the intake manifold rather then pump it back-and-forth?
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Are we saying here that if the secondary air pump causes problems you can just unplug and forget?
97' 3.0 Elite...
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Are we saying here that if the secondary air pump causes problems you can just unplug and forget?
97' 3.0 Elite...
;D yes... :y
Seems like we got carried-off with this theoretical discussion...
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Are we saying here that if the secondary air pump causes problems you can just unplug and forget?
97' 3.0 Elite...
Correct!
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Apologies again for the hijack, but clearly an intersesting subplot here.
Just to say that I remember something in the technical blurb for the second generation of "emission V8s" that Holden introduced in the early Eighties. They had improved emissions over the previous generation partly acheived through the use of a very mild performance camshaft which had an increased inlet/exhaust valve overlap. It's all starting to make sense.
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Excellent bit of advice there, I like solutions that include unplugging and forgetting :y