# spill valve on angle

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Hello every one,

I have a question about the spill valve on angle. I have installed a link G4+ GDI on an Audi A1 1.4i tfsi engine code CAXA. The problem with this engine, it has a normally closed spill valve where the link can only control a normally open spill valve. I am looking into different options to make it work when I came across the spill valve on angle. If you make this angle for examples 45 degrees, does it just extend its signal with the calculated energizing point as a start point or does it start energize the spill valve 45 degrees before this calculated point to achieve the desired rail pressure.

If it is the last option I can maybe 'hack' my way around not being able to drive a normally closed valve. If not, I will make a small board myself that will calculate the start point for energizing the valve in function of the crankshaft position. Then I can use this calculated energizing point of the link ECU as my endpoint.

Any other ideas are welcome.

thanks

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Best solution I can recommend is to move to the G5 setup that supports NC pumps natively. The pump control stuff is quite complicated with a few important differences between the NC and NO control methods, very specific timing requirements as it is all synchronous to engine speed and fuel pump solenoids also often require peak and hold drivers.

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Yeah i know that was what i wanted to but i am doing this for my final project in my bachelors degree and the school wanted a way to make this spill valve with this ECU work

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You'll want to power the output on maybe 5deg before the start of the lobe and then off partway through the lobe at the point that the remaining amount of lobe to the top of it is the amount of fuel that you want. So the start point is constant relative to the lobe with the end point getting closer to the peak of the lobe for less fuel and closer to the start of the lobe for more fuel.

In an NO you would be off until the same point as the end of the NC pulse and then on for a set number of degrees before the pump holds the solenoid shut with the pressure it has built up. This means your pulse is always the same length in degrees with the start of the pulse moving towards the peak of the lobe for less fuel and towards the start of the lobe for more fuel, turn it on too early though and you'll get no fuel as it won't build enough pressure within the hold angle to hold the valve shut.

Can you fit an NO style pump to the car? If you do your own software solution note that you need to keep track of the VVT angle of the cam that is controlling the pump as well as the crank position.

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I was also wondering if i could install a different pump but my university wants me to make this one work. For know i have vvt disabled so i could get this extra software running before.

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Definitely focus on just turning the output on with a peak and hold driver sometime before the start of the lobe and then use the start of the ECU's output as your off point then.

Note the pressure sensor is read synchronously by the ECU.

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Okay thanks. I just programmed an Arduino for tdc recognition as I assume there isn’t any way to let the ECU send out a puls on TDC?

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not without changing all your ignition outputs to fire at tdc instead of a variable angle beforehand. Don't forget you will have multiple lobes per engine cycle (often 3 lobes for 4cyl) and those lobes are spread across two crank revolutions as it is a 4 stroke motor.

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Yes I am taking all of that into account

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