Peak and hold injector driver board

[racingmini_mtl]

1. FR302DICT-ND / http://www.elfa.se/pdf/70/07010192.pdf
2. 13FR100E-ND / http://www.elfa.se/pdf/60/06002927.pdf
3. 39KEBK-ND / may I use 1/8 or 1/4W resistor - I can't find 1/6W

Hi,

1. FR302DICT-ND is rated at 3A while the part you refer to is only rated at 2A. The package is also different but would fit on the board since it is smaller.

2. Your replacement is electrically appropriate but will not physically fit on the board because it is bigger than 13FR100E-ND

3. 1/8W will work fine as long as you select a part that will fit on the board.

I don't know if you intented to buy boards from me or just wanted to duplicate the circuit. If you wanted to use my board, then you will have a problem with the sense resistor (13FR100E-ND) so you'll need to find another replacement. If you just want to do you own circuit then you're fine with your replacement if you select the one rated for 3W. In both cases, you should find a replacement diode rated at 3A or more.

Regards,
Jean

[racingmini_mtl]

2. Your replacement is electrically appropriate but will not physically fit on the board because it is bigger than 13FR100E-ND

I re-read the specs and the value has only a 5% precision. You should look for a sense resistor with a 1% precision to have the best results.

[schwepes]

thanks!

[risu]

To simplify wiring and to save space, DIYers etc could also make a small PCB which would be connected into MS FET-driver 8-pin socket in place of the actual driver? 2 channel PWM output could be done with the original MS FETs and TIP42. New tiny board would only have driver chips and DIL8-connector on it.

[racingmini_mtl]

To simplify wiring and to save space, DIYers etc could also make a small PCB which would be connected into MS FET-driver 8-pin socket in place of the actual driver? 2 channel PWM output could be done with the original MS FETs and TIP42. New tiny board would only have driver chips and DIL8-connector on it.

Would you care to elaborate on this? I'm not sure what driver chips you're talking about and how you would control the opening and PWM phases (or peak and hold). These are taken care of by the MS software normally or by the LM1949 in the case of my board and they vary depending on battery voltage.

In addition with the V3.0 PCB, you would still need to wire the flyback damper circuit away from the CPU and onto this new board. With the V2.2 PCB, you'd have to connect the flyback board. These circuits are completely eliminated with the P&H board because they become unnecessary.

regards,
Jean

[risu]

I was thinking about little pcb which consists of two so8 LM1949 and those 0.1 resistors and it would fit to normal DIL8-socket. Normally there's no need to relocate TIP42 which is already on MS-board, and FETs too.

FETs leg on MS-board would have to be disconneted from MS-board and it would be connected to this new PCB:s resistor. Though I'm not sure if it's a different GND in MSv3. At least on 2.2 it's the same ground with driver and fets. It's just a thought to minimize space and components. I admit I haven't searched through the datasheets so there might be something I've missed.

I've no intention to dismiss your effort with current layout, looks like you've done a good job with it.

[racingmini_mtl]

I was thinking about little pcb which consists of two so8 LM1949 and those 0.1 resistors and it would fit to normal DIL8-socket. Normally there's no need to relocate TIP42 which is already on MS-board, and FETs too.

FETs leg on MS-board would have to be disconneted from MS-board and it would be connected to this new PCB:s resistor. Though I'm not sure if it's a different GND in MSv3. At least on 2.2 it's the same ground with driver and fets. It's just a thought to minimize space and components. I admit I haven't searched through the datasheets so there might be something I've missed.

I've no intention to dismiss your effort with current layout, looks like you've done a good job with it.

I didn't think you were dismissing my work. I just didn't get what you ment at first but I got it later after my last post.

Even though it's an interesting idea, there are a few things that could make this impractical. The first thing is that the LM1949 is no longer available in an SO8 package, at least not that I could find. The second aspect is that the LM1949 is designed to drive a single injector. You probably could cheat and drive 2 injectors but you'd have to change the sense resistor (half the resistance and 4 times the power rating) and make sure the injectors are well matched so that they both receive the same current and open at the same time. There might also be a need to change the FETs because I'm not sure what can be driven by the LM1949.

Another point is that the LM1949 requires a non-inverted pulse signal which is not what is provided by the current code versions on MS1 and MS2. There could an inverter on the board or the code could be changed but that last option, while not difficult, would also require a change of the pull-up resistors to pull-down resistors. This is similar to what is done on Microsquirt.

The last point is that the MSV3.0 and V2.2 have differences in their injector driver circuit. That could require 2 different daughter boards depending the PCB version. It would also be nice to be able to use the sense resistors already present on the V3 board.

All these concerns might no be big issues. Actually, I'll have a look in more details at all those to see what would be the best solution in terms of small footprint and minimal connections.

Jean

[SuprAdam]

Hey...

I have an MSII V3.0 board and I am wondering about adding more injector drivers to the board.

I am using this unit on an inline 6 cylinder (supra motor) so I obviously have 6 injectors. As I am sure you all know the MSII board has two injector drivers, so using a 6 cylinder I would be wasting alot of fuel setting up 3 injectors to each driver.

Using the peek and hold expansion boards, would I be able to get away with adding one expansion board (4 injector drivers) and using the two original drivers, totalling 6 drivers? Or do you have to get rid of the original drivers when adding the expansion board? In that case, how do I use only 6 drivers? Can only 2 drivers be populated on one of the expansion boards without issues?

Option 2
Now I don't know if this is even possible but is there anyway to add ONE more injector driver to the original PCB? In the proto area or something, at least that way I can use the injectors in wasted spark, still wasting fuel but not as much as with 3 on one driver.

Obviously sequential injection is preffered but if I can easily get away with just piggy backing one more driver on...

I am not sure if it makes a difference but they are low impedence 680cc injectors.

Thanks.

[jsmcortina]

In what way are you wasting fuel? I think you misunderstand how the fueling works.

James

[racingmini_mtl]

SuprAdam,

There is a slight misunderstanding. The peak&hold board adds injector drivers but it does not add injector channels. So even if you were to put 1 or 2 boards you would still only have 2 channels so 3 injectors per channels.

Also, you have to understand that you will not be wasting fuel by putting 3 injectors per channel. Each injector will still inject the correct amount of fuel just not according to some pre-defined timing. If you want more details look at the Megamanual for an explanation why you don't need sequential injection.

Having said that, under certain very precise circumstances, sequential injection might be of benefice. I will be working on modifying the MS2/extra code to provide sequential injection for up to 4 cylinders but this will lose the PWM capability of the V3.0 drivers and will require some hardware modifications to the MS2 board. The peak&hold board will then be very useful. I might also implement the possibility to have semi-sequential injection for engines up to 8 cylinders but this will be for a later version.

Jean

[SuprAdam]

Ok now I am confused.

What is the diference between injector drivers and injector channels?

And if I have 3 injectors per channel, are they not going to be injecting as batch fire? 3 per combustion cycle? When really I only need two per cycle.


Ignition is 1-5 3-6 2-4

What is the point of having the expansion boards to add injector drivers if in the end they are all coming into only 2 channels?

Help?

[jsmcortina]

With any current Megasquirt you are going to be firing two banks of injectors. This works just fine on thousands of cars (and bikes) so no need to worry. In the early stages of an install it is very easy to over complicate things in the mind.

Connect three injectors to one bank and three to the other. Be sure to get the V3 board though for better support of low-z injectors.

James

[racingmini_mtl]

Ok now I am confused.

What is the diference between injector drivers and injector channels?

And if I have 3 injectors per channel, are they not going to be injecting as batch fire? 3 per combustion cycle? When really I only need two per cycle.


Ignition is 1-5 3-6 2-4

What is the point of having the expansion boards to add injector drivers if in the end they are all coming into only 2 channels?

Help?

The injector driver is the electronic circuit that drives the injector(s). The injector channel is what the code sees for the control of the injectors. The code uses the channel to turn on or off injectors and to pulse them (PWM). With MS, there are 2 injectors channels and 2 injector drivers. Each driver can drive many injectors but the code only controls 2 different sets of injectors.

The reason for the p&h board is that low-Z injectors need a peak and a hold phase to function correctly. With the standard MS drivers, this is done by first turning on the injector for full current (peak) and then through PWM where the injector is turned on and off very rapidly which gives a result similar to lowering the battery voltage and thus reducing the current (hold). With the high-resolution code (MS1/extra and the old HR code), the code loses the ability to do the PWM phase to gain the high resolution. That's where the p&h board comes into play because it has a specialized chip (LM1949) that automatically performs the peak and hold phase by sensing the current and controlling this current. These drivers only drive a single injector so that why you need as many of them as you have injectors but they are still controlled by the 2 channels.

As for the rest, do as James said. You'll see that you can actually have the injectors fired 1, 2, 3, or 6 times per engine cycle (720 degrees) and that there are pros and cons for these possibilities. Read the Megamanual over a few times and trust the people here when they tell you stuff that doesn't seem intuitive.

Jean

[Dohc Rocks]

I just ordered my Peak and Hold board today.

I am going to be running four 1000cc injectors on a Dodge Neon with a turbocharged 2.4 engine that I built. I am running a 50 trim turbo with hopes to step up to a 60-1 or a GT35R in the future.

I'll be sure to update how everything works.

That said, if this things does indeed work as it should then this should be a must buy on the shopping list of anyone running the high res code with low inpedance injectors.

[2001dodgeneonrt]

is there a diagram for connection between the 2 boards on ver 3.0?

[racingmini_mtl]

is there a diagram for connection between the 2 boards on ver 3.0?

There's no diagram as such. There's only a description on my web page. I'll see about making a diagram.

Jean

[Dohc Rocks]

I received both my board and Digikey shipment today.

I must say the board although simple in design is well laid out and plenty beefy. Assembly was a snap and after reading and rereading this post, I have everything all assembled and ready to go. I was surprised just how many parts you removed from the mainboard when adding in the Peak Hold board.

Here's a shot of my finished project.


I chose to use the SPR1 - SPR4 pinouts in the DB37 as my new injector connections... primarily because they were...well.. right where I needed them.

My setup BTW is:

Dodge 2.4L DOHC - fully forged
50 trim turbo
MSnS-E High Res
1000cc injectors
1020 Spearco intercooler
Lots of custom stuff like manifolds, brackets and the like.

Shooting for 450 whp and possibly a 60-1 next year.

[racingmini_mtl]

Nice and clean setup!

I'm wondering if you have wires under the board going from the SPR1-4 holes near the DB37 to the actual DB37 pins. If not, you might have problems because I don't think the board traces can handle the injector current.

Jean

[ca434sbc4]

I chose to use the SPR1 - SPR4 pinouts in the DB37 as my new injector connections... primarily because they were...well.. right where I needed them.



Caution - the DB37 contacts are only rated for 5 amps.

You may want to run the P&H outputs via a beefier connector (GM weatherpack for instance) good for 10 amps/pin.

[ca434sbc4]

I chose to use the SPR1 - SPR4 pinouts in the DB37 as my new injector connections... primarily because they were...well.. right where I needed them.



Caution - the DB37 contacts are only rated for 5 amps.

You may want to run the P&H outputs via a beefier connector (GM weatherpack for instance) good for 10 amps/pin.