I think you are all talking about the wrong thing guys. The engine component red circled in the earlier post is NOT the EGR valve, that is the secondary air injection pump. This pumps air into the exhaust manifold on start up to warm up the CAT quicker. The EGR valve is located on the top if the inlet manifold, you can't really see it unless you remove the header tank and wiring trough, and you have to remove the inlet and outlet fuel pipes to remove it. The secondary air pump only runs on start up and so removing it will not really gain any performance. The Haynes manuel is right on this, I know as I am planning to fit throttle bodies, and have had most of this stuff out to see where everything goes.
By the way Col if you are still there how did it go on wednesday.
stereo-rob,that sounds like the electric fuel pump priming its self.
AJBek,how does the secondary air injection pump help warm the cat,how does air in the exhaust make the cat warm quicker,does it ignite when injected cause of the high temp?
So,how do you disable the EGR?
Do you just take the EGR valve off the inlet manifold and make a plate to blank the manifold off?
Rob, The whirring noise on start up is the secondary air injection pump, the red circled component from the earlier post, not the EGR valve which is just a small valve located next to the inlet manifold on a casting on the cylinder head, it doesn't make any noise. Dathers, I think this is how the system works (though much of this is informed guesswork and may be wrong). The secondary air injector pump, and fuel tank vent valve and the EGR valve are controlled by the ECU. On the ECOTEC engine this is set up to mimimise emmissions. On start up the engine is cold and therefore needs more fuel to get going. Also the cat is cold and doesn't work too well. This means on a normal engine there would be some unburnt hydrocarbons and nitrogen oxides produced until the engine warms up. On the ECOTEC engine what happens is on start up the secondary air pump starts to work which pumps a greater volume of air into the exhuast manifold under pressure. This increase in volume helps in two ways. Firstly it carried more air further down the exhaust pipe. If it wasn't there the exhaust manifold and down pipe would get very hot but it would take a while before the cat (located further down the exhaust) would warm up. This greater volume of air simulates higher RPM ,carries more heat to the cat and means you dont get a hot exhuast manifold and a cold cat. The second way it helps is because of the EGR valve. On start up the EGR valve is probably closed, but soon after it will open to allow exhust gas from the exhaust manifold back into the inlet system to allow any petrol still in the exhaust gas to be reburnt which again reduces emmissions. If the secondary air pump is also on, this pushes more of the exhaust gas through the EGR than normal (for any given RPM) and helps reduce emmissions. Once the engine is warm or running at higher rpm you don't need this additional help and the pump switches off. All this complex gear is no help at all when it comes to performance as hot exhaust gas in the inlet allows less cold air into the engine which you need for more power. Unfortunately the ECU will put up a fault code if it is disconnected, causing the warning light to come on and possibly affecting performance. However you don't need all this to pass the MOT. As long as the engine is fully warm and the CAT and lambda sensor work you should be fine. The earlier GSI C16XE engines didn't have EGR or secondary air injection, and they still passed the MOT.
As regards removing the EGR, making a plate to cover where the valve would normally be on the cylinder head would do the job mechanically, but you would still have the problem of the ECU fault code. I believe you can use a resistor to fool the ECU, but am not sure exactly what to do with it. It doesn't matter to me anyway as I am getting a mappable ECU with my kit.
cheers for the explanation,exellent!
I was thinking along the lines of taking the EGR valve off and blanking both the actual valve and the hole where the valve was origionally mounted,so the ECU would still think its there but in effect it wouldnt do any thing.do ya rekon that would work?
Ill leave the air injection thing if it only works at startup.
The c16xe reaches peak torque 500rpm earlier than the z16xe,what causes this?is the ecu program different or is it the EGR.
I also thought of buying an autronic mappable ecu with throttle bodys in mind for the futre,nothrottle bodies yet though,skint.
but could afford the ecu.what ecu you getting?
I am getting the MBE ECU, but only because that is what SBD supply. I have heard that emerald is pretty good as long as you are close to someone who can map it. As I stay up here it is much easier to get a premapped ECU from SBD, but if I stayed down south I might have got a different one, for example AndyH has a GEMS ECU which works well for him. As far as the EGR goes I think there is more to it than simply disconnecting the valve for the extra power (though you should see a small improvement). To get the same power as the C16XE I think you need to modify the head as well.