GDI4 ECU current supply

sutol
Posts: 9
Joined: Sun May 07, 2017 5:29 pm

GDI4 ECU current supply

Post by sutol »

Hello!
I am planning ahead an electrical system for my track car. The ECU is GDI4 and I would like to use it to power directly most of the engine components which (as far as I see from the datasheet it can do):

- Lambda (heater)
- DBW (58-61)
- GDI pump (32,58)
- 4 GDI injectors (24-27,51-54)
- 4 low-impedance ID1050x injectors
- wastegate control solenoids (49,30)
- 4 COP coils (2-5)
- 2 VVT solenoids (33,34)

Current for all this is provided via pins 56 and 57? So what is the power rating of those pins and what amperage output (group of outputs) on PDM should I dedicate to ECU and all these consumers?
TimH
JT Innovations
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Re: GDI4 ECU current supply

Post by TimH »

Most outputs are low-side drives so it's more down to the current-sinking ability of the ground connections rather than the limit of the VBatt pins. DBW and GDi high side drives are the exception to that.

Datasheet and other documentation shows what each drive output is capable of. But, basically, what you are planning seems to be within the specifications of the ECU. But the H-bridge outputs are 4x half-bridge according to the datasheet whereas a DBW motor usually uses a full bridge - that's something I'd want to check with tech support.
sutol
Posts: 9
Joined: Sun May 07, 2017 5:29 pm

Re: GDI4 ECU current supply

Post by sutol »

Thank you, Tim!

Yes I understand that most of the components that I've listed would have the 12V coming to them from PDM, and ECU sinking/switching the grounds.
But how would the fuel outputs be wired if used for lo-side PWM? Say:
- two fuel pumps
- two water pumps
Is the fuel output used as a "PWM ground" in this case as well?

The two H-bridge outputs should be enough to control the DBW throttle, below is the factory ford schematics
throttle.jpg
throttle.jpg (69.01 KiB) Viewed 1923 times
TimH
JT Innovations
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Re: GDI4 ECU current supply

Post by TimH »

PWM using low-side drivers is still the ECU sinking current - no different to an injector drive.

However, it is generally not a good idea to drive fuel pumps or water pumps direct from the ECU - they just take too much current. If you want to PWM these, use external solid state relays.

DBW motor is generally 5-6Amps and fine - but, as said before, they are usually driven by a full bridge driver not a half bridge. A full bridge has control of both sides of the motor. A half-bridge drive may be just fine - it's just that I have no practical experience of driving them like that.
sutol
Posts: 9
Joined: Sun May 07, 2017 5:29 pm

Re: GDI4 ECU current supply

Post by sutol »

Yes Tim,
I've specified that in the post before that I mean low-side PWM, so having an SSR for example in-between the pump and Fuel output of ECU, and controlling the SSR SIGNAL GROUND.

Isn't the common practice to have two half-bridge outputs designated for DBW control, thus making a full-bridge?
H-BRIDGE #03 / DBW MOTOR +
H-BRIDGE #04 / DBW MOTOR -
stevieturbo
Posts: 961
Joined: Sun Dec 07, 2008 2:04 pm

Re: GDI4 ECU current supply

Post by stevieturbo »

Odd question.

This is in the S8 section.

You're asking about a GDI4 ecu ? ( ok, similar )

But then you also mention a PDM....3 different devices ? The ECU is not a PDM.

So exactly what do you have ?

And I would say NO....you cannot ( or should not ) drive high or constant load devices from the ecu directly. eg, fuel pumps, fans etc etc

injectors, solenoids, coils and the like are all momentary.
TimH
JT Innovations
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Re: GDI4 ECU current supply

Post by TimH »

There is no GDi4 section and, as I understand it, the GDi4 is a variant S8 anyway.

As said by Stevie, do not drive constant current devices such as pumps direct. Nor PWM high current devices (such as pumps).

And I can't see a way in SCal of assigning a pair of half bridges to a DBW motor. But maybe with the GDi4 that's the way to do it - I don't know - hence the suggestion to ask Syvecs tech support.
stevieturbo
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Joined: Sun Dec 07, 2008 2:04 pm

Re: GDI4 ECU current supply

Post by stevieturbo »

TimH wrote: Tue Jun 02, 2020 9:46 pm There is no GDi4 section and, as I understand it, the GDi4 is a variant S8 anyway.

As said by Stevie, do not drive constant current devices such as pumps direct. Nor PWM high current devices (such as pumps).

And I can't see a way in SCal of assigning a pair of half bridges to a DBW motor. But maybe with the GDi4 that's the way to do it - I don't know - hence the suggestion to ask Syvecs tech support.
The normal way of driving the DBW though from say an S8, IS with two of those outputs, even if only one is specifically assigned.

ie, +ve to HBridge 01, and -ve to Hbridge02 assigned as full bridge.

Or for a positive 12v PWM trigger to something instead of lo-side ( in my case this is a time delay relay that needs a 12v trigger ), I have this wired to HBridge03, and nothing to Hbridge04, again configured as full bridge.
TimH
JT Innovations
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Re: GDI4 ECU current supply

Post by TimH »

yes, but the GDi4 spec does not mention it having full-bridge capability. It's probably just not written very well. But I still commend checking with Syvecs as these little things are there to bite!
stevieturbo
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Re: GDI4 ECU current supply

Post by stevieturbo »

TimH wrote: Tue Jun 02, 2020 9:56 pm yes, but the GDi4 spec does not mention it having full-bridge capability. It's probably just not written very well. But I still commend checking with Syvecs as these little things are there to bite!
mmm good point. But if it's based on an S8....surely it would have ?
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