[info] bosch 7506280 GDI driver

[AndreyB]

BMW 760 e65/e66 had separate electrics boxes just to drive direct injectors - those were the early days of GDI. Each v12 engine was running using two of these blocks - each box controls 6 lowZ injectors. Overall they had 5 separate control units to run that N73 v12 engine.

We got one of these boxes - bosch 7506280 from BMW 760 - to click a GDI injector. Two wires to GND, two wires to +12v. Low-side control signal - and it's alive Next step is hooking this to an oscilloscope.

Engine wiring diagram is located at https://github.com/rusefi/rusefi/wiki/BMW-N73

The larger chip says 30429, obviously google knows nothing about this 30429.

P-MQFP-44 chip is infineon sakc505 - that's a 8-Bit Single-Chip Microcontroller with CAN, datasheet is available.

[960]

This should be the diagram for the ECU:

GDI Driver CJ830:

MED7511C2_439_7.1.3.pdf

(143.98 KiB) Downloaded 868 times

MCU:

MED7511C2_439_7.1.2.pdf

(278.13 KiB) Downloaded 701 times

IN/Outputs:

MED7511C2_439_7.1.1.pdf

(378.46 KiB) Downloaded 689 times

[960]

Just saw your PCB picture.

Is this a pure GDI driver box?

Is it only controlling two injectors?

The big IC looks like the ASIC you find in all older Bosch ecus.

[AndreyB]

Is this a pure GDI driver box?

Is it only controlling two injectors?

Yes, just edited first post in this thread to make it less confusing

[AndreyB]

Do we know enough about typical GDI flow rate and typical rail pressure to know typical GDI pulse duration per engine cycle?

Are we interested to hook up an oscilloscope anywhere? Can we/do we need to measure current, voltage or what?

https://www.youtube.com/watch?v=SEP8Q6gHIEk

[Simon@FutureProof]

Without even looking to check I can say you are looking at anything from 12 to 35 bar for pressures depending on the injectors so pulse width is all over the place.

In terms of running the engine (ignoring emissions and knock limited stuff) then any pressure around 20bar will do and adjust the fuel from there.

Probably worth just fixing the pressure and adjusting fuel until you can start it as normal.

Are there no flow rates for those injectors published?

[AndreyB]

Those are OEM pigtails for that driver box. Cute how they did not have 12 thick wires on the right outputs plug so some injectors are using two small pins where some injectors are using one large pin.

[ssmith]

Without even looking to check I can say you are looking at anything from 12 to 35 bar for pressures depending on the injectors so pulse width is all over the place.

In terms of running the engine (ignoring emissions and knock limited stuff) then any pressure around 20bar will do and adjust the fuel from there.

Probably worth just fixing the pressure and adjusting fuel until you can start it as normal.

Are there no flow rates for those injectors published?

BMW N20/N55/S55 is 50-200 bar; newer engines push 300 or maybe 350 bar. Because of the relationship of pressure to flow rate, 200 bar is only 2x the flow of 50 bar (square root of the ratio). The engine in question here may be old enough that the pressures are lower.

For my N20, I run 50 bar at idle (785 RPM, 30 kPa MAP) and the injector pulsewidth is around 1.2ms. As far as I can tell, deadtime on these injectors is close to 0.0ms, though I'm sure it's closer to 0.1-0.3ms. At 6700 RPM making around 200-210 rwhp, MAP=182kPa, fuel pressure = 200bar, pulsewidth is 5.3ms. This corresponds to about 213 degrees of crank rotation, if I'm doing the math correctly. The limit is a little under 360 degrees, as the positive rail is shared between two injectors operating on opposite crank cycles.