4+4 injectors - which used when & how to tell?

[cupra14]

I understand my Cupra 2.0 280 has a set of 4 injectors (DI - direct injection ones) fed by a high pressure pump and another set of 4 from a low pressure pump.

When is each set used?

How can I tell?

The potential advantage of the 4 low pressure ones is they may reduce or prevent carbon fouling which the DI ones can cause.

Sorry if I've missed posts about this. Any other forums?

 

[LouG]

As I understand the system, the DI is the main system and operates throughout the engine operating profiles, the port injectors come in at high load/rpm profiles. That's how the Toyota D4S system worked. They are both high pressure systems, but DI is higher.

 

[cupra14]

I'm pretty sure about the high & low pressure pumps as the DI & others are shown as high & low pressure in SSP 606. Sadly its "explanation" (page 49) is not exactly clear and doesn't say how anyone could tell when the injector sets are actually being used.

 

[Chrispy]

SSP606 (mentioned above) has a nice map of speed/load and injection type.

To tell while running you can look in something like VCDS. There are live data channels for "number of injections" for each type. Whichever is increasing is the one being used.

Or if you happen to have thousands of pounds of data acquisition systems lying around you can fit current sensors on the injector feed wires and measure that (but a whole pulse is about 2ms so you need something fast like an oscilloscope).


There is also some strategy where if the engine has been running under direct injection for a long time it will use the port injectors to try and keep the intake valves clean.

 

[cupra14]

Thanks. VCDS while driving looks iffy but maybe!

 

[mm46]

The potential advantage of the 4 low pressure ones is they may reduce or prevent carbon fouling which the DI ones can cause.

Yes, they are preventing carbon build-up because they are cleaning the valves

As I understand the system, the DI is the main system and operates throughout the engine operating profiles, the port injectors come in at high load/rpm profiles. That's how the Toyota D4S system worked. They are both high pressure systems, but DI is higher.

Port injection is used under lower load
https://www.seat-mediacenter.com/ne...-leon-cupra-290-now-with-even-more-power.html

the gasoline direct injection is complemented under partial load by manifold injection

https://www.aachener-kolloquium.de/images/tagungsunterlagen/2011_20._ACK/A1.1_Wurms_Audi.pdf
page 8

Using the dual injection system allows the optimum fuel injection to be selected in every load range (intake manifold injection under low loads and direct injection under medium and high loads)

 

[LouG]

I'm pretty sure about the high & low pressure pumps as the DI & others are shown as high & low pressure in SSP 606. Sadly its "explanation" (page 49) is not exactly clear and doesn't say how anyone could tell when the injector sets are actually being used.

OK. I should have been clearer. Port injection generally runs around 40 - 60 psi, supplied by a pump which is considered high pressure compared to carbed engines and mechanical injection systems. Direct inject is generally around 2300 psi, and much higher in diesels.

 

[LouG]

Port injection is used under lower load
https://www.seat-mediacenter.com/ne...-leon-cupra-290-now-with-even-more-power.html

That's different to D4S. It seems strange to use port injection only under partial load. I'd have to see tech specs not just a brochure.

PS. I've just found that direct/port injection protocols are many and varied. Depending on the characteristics the designer wants, so it's quite possible VW use port injection only as a emmisions/cooling protocol and not peak power like Toyota.

 

[cupra14]

Thanks! Especially for the PDF link