Number of injector outputs with MS3 processor board

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mega_user
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Number of injector outputs with MS3 processor board

Post by mega_user »

I have built a custom injector driver board to use with MS3 processor fitted on a V3.0 mainboard.
I have only 4 injector drivers controlling 8 injectors on a V8. How do I enter in Tunerstudio the correct settings so the software knows there are only 4 injector drivers active?
I suppose when I choose Main fuel outputs as MS3X fuel, the sotware assumes all 8 injector drivers are connected to injectors for a V8 setup.
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Re: Number of injector outputs with MS3 processor board

Post by Barton »

using a multipoint non sequential or batch fired injection like this (sorry I forgot don't turn on the injector trim)
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billr
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Re: Number of injector outputs with MS3 processor board

Post by billr »

I think you can simply set it for 4 injectors, the MS3 will only drive those "MS3X" outputs. I assume you are connecting your custom drivers to the header on the MS3 board itself, correct? That's what I am doing. I have an MS3X, but the injector drive bypasses it since I wanted P&H.
mega_user
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Re: Number of injector outputs with MS3 processor board

Post by mega_user »

Yes I'm using the MS3 board signals intended for driving the MS3X board from the header.

I built this board to test it, before using it on a future V12 project.

It is the same on a V12 engine using only six injector drivers from MS3X, each connected to 2 injectors.

I would also like to test the semi-sequential mode. It is possible for one injector otput to drive two injectors for the semi-seq mode? How does semi-sequential mode work?
Does it want all the injector drivers connected and then fires them in pairs? Or can can I use just the half of the injector drivers?

I checked the Megasquirt3_TunerStudio_MS_Lite_Reference-1.4.pdf (and 1.3 and 1.5) and Number of injectors setting (from the picture a few posts before) is not mentioned. While all the other setting are explained.

I tried entering 4 in this setting and the engine will not run as it should. It throws off the fueling completely.

Using only the first four injector outputs driving two injectors at once:
It runs fine with sequential off , 8 injectors and 2 squirts per engine cyle at 1.5ms at idle. Leaving it at 1 squirt per engine cycle and 3ms at idle it runs very poorly.
When trying semi sequential it will not run at all at idle. I have to lower the pulsewith to 1.0ms and it still runs rich. (also the injectors start to behave strangely at such short pulsewidths)
(everytime corrections are made to get to 13:1 to 14:1 AFR at idle)

The question is. Will MS3 run semi-sequential with only 2 injector outputs connected to 4 injectors, or 3 to 6 or 4 to 8 , 5 to 10 or 6 to 12?
If so, how to enter the correct settings?
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Re: Number of injector outputs with MS3 processor board

Post by jsmcortina »

:msq:
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mega_user
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Re: Number of injector outputs with MS3 processor board

Post by mega_user »

This is the msq. The Fuel VE table is still prety rough. But the car drives nice.

sequential off , 8 injectors and 2 squirts per engine cycle. 1.5ms at idle
req fuel 11ms

When tested with semi-seq req fuel must be set at 2ms. (Fuel VE table staying the same) and it will still run rich at 12:1 and only 1msec PW.

How to tell to the MS3 sotware that it should use only 4 injector outputs (in my case) to run semi-sequential ?


Checking the manual again:

"Semi-Sequential - Fire injectors in pair and allow the angle of injection to be specified, does not
require a cam sensor. Injectors should be wired in the same manner they would be wired for fully
sequential injection."

I suppose MS3 needs all the injectors drivers wired up to the appropriate injectors to run semi sequential.

I have another question , from the manual
"Off - Use batch injection. On MS3X outputs or on MS3-Pro, the channels are divided into two
groups, and all injectors in a group are squirted simultaneously."

Which injectors are in which group? 1 to 4 in group one and 5 to 8 in group 2 in the case of a V8 engine?
This explains why it needs 2 squirts per engine cycle to run decently. But it actually runs 1 squirt per engine cycle since the batch fire injector groups are alternating.
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Re: Number of injector outputs with MS3 processor board

Post by mega_user »

Did some more research through the user manuals. MS2 with two additional injector drivers will run 8 cylinder semi-sequential with 4 injector drivers.

Will there be an upgrade to bring MS3 semi-sequential to MS2 semi-sequential logic?
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Re: Number of injector outputs with MS3 processor board

Post by jsmcortina »

The code doesn't expect you to run eight injectors from four outputs when the MS3X is the standard way to control things.
You likely can work around it by setting four injectors and doubling the injector cc to calculate the correct Req Fuel.

James
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mega_user
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Re: Number of injector outputs with MS3 processor board

Post by mega_user »

It will run only in batch mode. Setting it to 4 injectors I can not get it to idle. No req fuel change and VE table changw will help it. The engine runs like it is running on 4 cylinders.

This means that for a 12 cylinder engine an additional 4 injector driver board is a must. It will not run a V12 semi-sequential from 6 injector drivers.
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Re: Number of injector outputs with MS3 processor board

Post by billr »

Post an MSQ with the correct injector flow. Post the resistance of your injectors. Let's at least have all the facts to work with.

What vendor are the P&H drivers from, or is it your own design?

What is your intake configuration (dual-plane, single plane, individual runner, ITB, etc)?

Post an MSL of it running and idling poorly. (And please, be sure it is taken using the MSQ posted!)

Has spark timing been verified with a simple timing light on all cylinders?

Have you tried firing it with various injector disabled, to verify which cylinders aren't firing due to fueling?

It may help to post a sketch of how you have the injectors wired.
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Re: Number of injector outputs with MS3 processor board

Post by jsmcortina »

You are running old firmware. Consider upgrading to current.

James
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mega_user
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Re: Number of injector outputs with MS3 processor board

Post by mega_user »

The injector driver board is designed as suggested in the MS3 manual for a V12 configuration. Basically a copy of the MS3X injector driver schematics. But with only four injectors drivers.
Before installing it into a future V12 project I decided to test it on a V8 engine. And conveniently test it in semi-seq mode, since it should run a little beter than in batch mode.

Injectors are standard high impendance Bosch 14Ohm 280cc. Single throttle body . Efi manifold with a plenum and 8 runners.

I did not made an MSL datalog at the time.

The timing was checked. At idle, at 3000 and 5000 rpm. It is rock solid.

All injectors are firing. They are wired in pairs like coils in wasted spark configurations.


The engine is being worked on right now, for a mild rebuild and more power, since it runs really nice with MS3 even in batch mode and on 4 injector drivers.
After it is done I will load the latest firmware and test the injector board again. By then I should also get an MS3X and let it run with all 8 injectors.


It is possible that no one ever thought of running semi-seq setup on 4 injector drivers with 8 injectors? Since when choosing MS3X outputs the software assumes
all the injector drivers are connected to the appropriate injectors. But it would be nice to run a V12 semi-seq on 6 injector drivers. There are even some V10 out there.

I explained the engine behavior in previous posts, what happens when testing the various setting. In batch mode it will run fine.



I still have one last question unanswered and can not find an answer in the manuals or the forums :

Per the manual
"Off - Use batch injection. On MS3X outputs or on MS3-Pro, the channels are divided into two groups, and all injectors in a group are squirted simultaneously."

Which injectors are in which group? 1 to 4 in group one and 5 to 8 in group 2 in the case of a V8 engine?
This explains why it needs 2 squirts per engine cycle to run decently. But it actually runs 1 squirt per engine cycle since the batch fire injector groups are alternating.


As said before after all is done I will load the latest firmware and test the injector board again. By then I should also get an MS3X and let it run with all 8 injectors.
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Re: Number of injector outputs with MS3 processor board

Post by jsmcortina »

mega_user wrote:it would be nice to run a V12 semi-seq on 6 injector drivers. There are even some V10 out there.
For these engines it is 'expected' that the MS3X board is in use.

For V12 semi-seq it is assumed that 6 injector drivers are being used.
For V8 semi-seq it is assumed that 8 injector drivers are being used.

James
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Re: Number of injector outputs with MS3 processor board

Post by billr »

"Postby billr » Fri Jul 28, 2017 8:58 am
I think you can simply set it for 4 injectors, the MS3 will only drive those "MS3X" outputs."


I'll upgrade that to "I know you can simply set it for..." Before I bought the MS3X and P&H boards I drove my 8 injectors from four old Cherry CS453 P&H ICs, two injectors paralleled on each driver.
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Re: Number of injector outputs with MS3 processor board

Post by mega_user »

Great to hear that. It would be great if the manuals will be updated with this information.

jsmcortina wrote: For these engines it is 'expected' that the MS3X board is in use.

For V12 semi-seq it is assumed that 6 injector drivers are being used.
For V8 semi-seq it is assumed that 8 injector drivers are being used.

James
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Re: Number of injector outputs with MS3 processor board

Post by jacky4566 »

Ok I'm confused.

You are running 8 injectors tied in pairs using the MS3x outputs.

Why can he simply not tie the pairs to Outputs 1-4 and use semi sequential mode? Yes all 8 output will fire but that doesn't matter if 4 of them get ignored.
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Re: Number of injector outputs with MS3 processor board

Post by rabid »

jsmcortina wrote: For V12 semi-seq it is assumed that 6 injector drivers are being used.
For V8 semi-seq it is assumed that 8 injector drivers are being used.

James
Interesting. Then I assume a 4 cylinder would require that 4 injector drivers are used even with semi-sequential. I am trying to run two batches of two injectors in semi-sequential on a 1.6L miata because the class rules prohibit modding the wiring to get the extra wires into the ecu.
jacky4566 wrote:Ok I'm confused.

You are running 8 injectors tied in pairs using the MS3x outputs.

Why can he simply not tie the pairs to Outputs 1-4 and use semi sequential mode? Yes all 8 output will fire but that doesn't matter if 4 of them get ignored.
I agree. Isn't there going to be pairs of outputs firing simultaneously? So just wire up to one of each pair? (This assumes you don't overload the output)
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Re: Number of injector outputs with MS3 processor board

Post by racingmini_mtl »

rabid wrote:Isn't there going to be pairs of outputs firing simultaneously? So just wire up to one of each pair? (This assumes you don't overload the output)
Yes and yes. If you have to run the injectors in 2 pairs due to the wiring then you simply 'lose' 2 injector outputs that cannot be used for other purposes. And 2 high impedance injectors can be driven by one injector output; that won't overload the driver.

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Re: Number of injector outputs with MS3 processor board

Post by V12StealthHunter »

Feel free to tell me to RTFM here but how are you guys physically wiring your paired injectors. Typical Bosch EV14s are 12ohms. So in parallel its only 6ohms. Will that not overload the high impedance injector driver?

For anyone who lands here doing V12 research, as far as I can tell from the docs online, the MS3Pro can be configured to run 12 sequential injectors.

And want to second that this piece of information was very hard to find. These assumptions could be documented better.
mega_user wrote:Great to hear that. It would be great if the manuals will be updated with this information.
jsmcortina wrote: For these engines it is 'expected' that the MS3X board is in use.

For V12 semi-seq it is assumed that 6 injector drivers are being used.
For V8 semi-seq it is assumed that 8 injector drivers are being used.


James
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