What are injector bank 1+2 doing?

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jesse408
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What are injector bank 1+2 doing?

Post by jesse408 »

I have the sequential mod done on the MS2 v 3.0 main board, and I have peak and hold boards installed.
In Tuner Studio, I have selected "external drivers".
In this case, what are my original (now unused) injector bank 1+2 drivers doing, if anything? I have not checked to see for myself. I'm just curious if the bank 1+2 circuit could be used to do something else like a programmable output or a tacho driver or something useful.
billr
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Re: What are injector bank 1+2 doing?

Post by billr »

Yes, they are available for other purposes if not being used for injectors. They can be pretty useful, since they are "high current" and are PWM-capable. One use I know of is for driving a fuel pump in closed-loop for fuel-pressure control.
grom_e30
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Re: What are injector bank 1+2 doing?

Post by grom_e30 »

on ms2 do you not still use the bank 1+2 cpu pins to control the peak and hold driver board? if that was the case i would assume the normal channels could not be re-purposed
1990 bmw 320i daily driver with m20b25 ms3 sequential fuel, 380cc injectors, d585 coil near plug, home made cam sync, launch control, fan control, vss, homebrew egt logging what's next????
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Re: What are injector bank 1+2 doing?

Post by racingmini_mtl »

The peak and hold drivers use the same processor pins as the main board drivers whether or not they are used with the additional driver modifications. So the output of the main board drivers cannot be used for anything else as there is nothing you can do to control them independently unless you do some major board modifications and find free processor pins.

What you get on the main board driver outputs at this time with the additional injector modification is not usable as each output is a combination of 2 injector channels.

Jean
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racingmini_mtl
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Re: What are injector bank 1+2 doing?

Post by racingmini_mtl »

billr wrote:Yes, they are available for other purposes if not being used for injectors. They can be pretty useful, since they are "high current" and are PWM-capable. One use I know of is for driving a fuel pump in closed-loop for fuel-pressure control.
Bill,

You're thinking of MS3 with MS3X. With MS2 and the additional injector channels, that's not the case.

Jean
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jesse408
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Re: What are injector bank 1+2 doing?

Post by jesse408 »

Thank you fellas.
Good to know.
billr
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Re: What are injector bank 1+2 doing?

Post by billr »

Sorry about the bogus advice, I definitely was thinking MS3!
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Re: What are injector bank 1+2 doing?

Post by dontz125 »

They may not be selectable in firmware as such, but there's nothing stopping you from selecting JS11 as a ProgOut or boost control and jumpering to R15 or R20, and driving those nice big Mosfets that way.
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Re: What are injector bank 1+2 doing?

Post by racingmini_mtl »

dontz125 wrote:They may not be selectable in firmware as such, but there's nothing stopping you from selecting JS11 as a ProgOut or boost control and jumpering to R15 or R20, and driving those nice big Mosfets that way.
Yeah but that still requires making sure the main board drivers are completely disconnected from the processor and the additional p&h drivers. That's not obvious to most. Moreover, those nice big Mosfets are not logic level so they need a fet driver which means you can't directly connect to R15 or R20 from a processor pin.

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Re: What are injector bank 1+2 doing?

Post by dontz125 »

Details, details ... Ok - clip / lift the PWM0/1 pins at the socket, make sure there's no shorting. Then jump JS11 etc to the U4-side of R14/17.
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Re: What are injector bank 1+2 doing?

Post by racingmini_mtl »

dontz125 wrote:Details, details ... Ok - clip / lift the PWM0/1 pins at the socket, make sure there's no shorting. Then jump JS11 etc to the U4-side of R14/17.
The 1st and 2nd injector channels are connected to the damping circuits (3rd and 4th are separate from the main board drivers). So that also has to be taken care of.

I understand the desire to reuse hardware but if you're talking about a "non-standard" modification (for lack of a better term) please be careful to examine and detail all the aspects of the modifications you propose. Failure to do so may lead to failures in someone else's setup and that could be expensive.

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dontz125
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Re: What are injector bank 1+2 doing?

Post by dontz125 »

Conceded. I hate blowing up my own stuff; blowing up other people's because they took a suggestion of mine is something I've managed to avoid so far.

That said ... If R32 & R36 were removed, ch3 & 4 would be isolated from whatever was happening in the INJ1 & 2 circuitry.

As an option, if jumpers were added from the bases of Q10 & Q13 to the 'join here' points of R14 & 17. At that point, an 'ON' signal from JS11 etc would trigger the FB circuits; an 'OFF' signal would cut the FB circuit but activate the FET driver.

Thoughts?
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racingmini_mtl
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Re: What are injector bank 1+2 doing?

Post by racingmini_mtl »

dontz125 wrote:That said ... If R32 & R36 were removed, ch3 & 4 would be isolated from whatever was happening in the INJ1 & 2 circuitry.
Removing the resistors would indeed isolate the injector signals from the main board driver circuits but that would be for channels 1 and 2. Channels 3 and 4 use the crystal pins which are already isolated from the drivers.
dontz125 wrote:As an option, if jumpers were added from the bases of Q10 & Q13 to the 'join here' points of R14 & 17. At that point, an 'ON' signal from JS11 etc would trigger the FB circuits; an 'OFF' signal would cut the FB circuit but activate the FET driver.
I'm confused. Unless you cut traces, the fet driver is connected to the MS2 card. Or are you talking about the same setup you mentioned before with the clipped pins? In any case, it seems a much better thing to remove the resistors rather than running the jumpers.

My recommendation is to not populate the main board circuits if you're going to use additional drivers. That leaves a good part of the board free as well as almost all of the heat sink locations. If you want other outputs, use the free heat sink locations and possibly some of the free component locations (as long as you don't use R32, R36) to make the minimal output circuit and even use the freed up connector locations; you'll obviously need some jumpers to connect those circuits. If the board is already fully populated, then don't use the main board injector driver circuits at all and if you do need more outputs, remove the few components needed to free up heat sink locations and the connector pins.

Jean
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dontz125
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Re: What are injector bank 1+2 doing?

Post by dontz125 »

racingmini_mtl wrote:Removing the resistors would indeed isolate the injector signals from the main board driver circuits but that would be for channels 1 and 2. Channels 3 and 4 use the crystal pins which are already isolated from the drivers.
*sigh* You know, I was looking at the schematic on your site, just before I typed that ...

Yes, that was 'part 2' of the previous mod - clip & isolate DIP40-21 & 22, remove R32 & 36, jumpers from the desired JS pins to R14 & 17, with the option of jumpers from R14/17 to R32/36 if flyback protection is needed / wanted.

I agree that with an unpopulated board it's probably easier to sort out your own components, but for a fully assembled board - home-built, store-bought, or even a 3.57 - I do think that the INJ1/2 circuits are a viable choice.
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