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> MicroSquit Conversion, Giving this a try
N_Jay
post Oct 8 2016, 07:13 AM
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QUOTE(Mark Henry @ Oct 7 2016, 04:57 PM) *

QUOTE(N_Jay @ Oct 7 2016, 04:57 PM) *

I see where the manual talks about the resistors slowing down the opening.
I am not sure the peak and hold would be as good as building a constant current driver (or is the engineer in me over designing?)

Maybe just put a capacitor across the resistor?

I have a hard time believing that one, the resistor limits current but slowing it down? That's like putting a throttle on light.

I've run 2.0 D-jet injectors with no issues, my engine now has Siemens deka 55 lbs low impedance injectors. BTW stock 2.0 injectors can handle 200 hp easy, stock engine you won't be seeing any more than 35% duty cycle.
The only issue I see with low impedance is the resistor pack gets hot and needs to be away from things that could melt. If you are making your own resistor pack mount them on a aluminum plate for a heat sink.


The difference between resistance and inductance.
The injector is a coil, so the resistance is when you measure steady-state (DC) with an Ohm meter.
The inductance will be significantly higher, because the coil will resist inrush of current.
The greater the impedance of the power supply (The internal resistance of the battery and all resistance prior to the coil), the slower this ramp up of current (and hence the opening of the injector) is.

But as I said, probably over engineering.
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N_Jay
post Oct 8 2016, 07:20 AM
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QUOTE(Dtjaden @ Oct 7 2016, 06:10 PM) *

QUOTE(N_Jay @ Oct 7 2016, 01:57 PM) *

QUOTE(Dtjaden @ Oct 7 2016, 03:12 PM) *

I appreciate all of the intelectual comments. I am afraid they will most likely confuse the OP. If he simply find follows the recommendation in the Megasquirt/Microsquirt manuals all will be good.

By the way 2.0 injectors check out at slightly less than 2.5 ohms when cold.


I see where the manual talks about the resistors slowing down the opening.
I am not sure the peak and hold would be as good as building a constant current driver (or is the engineer in me over designing?)

Maybe just put a capacitor across the resistor?

The reason for a peak and hold driver is that it provides a burst of current to open the injector and then drops the current to a lesser level that keeps the injector open. You get the best of both worlds - fast opening and lower average current.

A capacitor across the resistor would do the opposite of what is needed, it would slow both the opening and closing.


The Peak and Hold gets high owning current and low average holding current by PWM the signal. Not a bad solution as long as the PWM does not let the injector start to close.
I don't see how a capacitor across the resistor would slow the opening or closing?
Sized correctly, it would bypass the resistor for the initial inrush, and then as it charged the resistor would be the primary current limit. As for closing, I would have to give it some more thought. (Been a while since I did any circuit design work)

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N_Jay
post Oct 8 2016, 07:30 AM
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QUOTE(Mblizzard @ Oct 8 2016, 07:41 AM) *


Ok still thinking about the placement of the resistors. Because the ground is common to both the injectors and they essentially fire at the same time would there not be another 2.5 Ohms of resistance in the circuit?

If so, placing the resistor in the location shown would make more sense as the 3 Ohm recommend by the DIYautotune would give the needed resistance.



The order of the resistor and the injector in the flow of current between the source (the battery switched by the "Fuel Pump" relay) and the return path (Provided by the injector "output" of the MS unit) does not matter.

The resistor limits the current flow to an amount that the injector can handle given the highest duty cycle expected. (Plus some margin)

Thinking of one side as "Grounded" rather then just a return connection can add confusion.

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Phoenix914
post Oct 8 2016, 08:37 AM
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Since my engine is out, I'm thinking it would be a good idea to mount a 36 tooth trigger wheel in case I want to add a new injection/ignition system later.


Although I can't add to the discussion about how the injection and ignition systems work, I can comment on resistors in the system. If you place resistors in series in a circuit, they don't add linearly. They add like 1/R = (1/R1) + (1/R2).

So if you have a 2.5 and a 3 ohm in series, the total resistance will be 1.36 ohms.

Just sayin' (IMG:style_emoticons/default/smile.gif)
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stugray
post Oct 8 2016, 09:15 AM
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QUOTE(Phoenix914 @ Oct 8 2016, 08:37 AM) *

Since my engine is out, I'm thinking it would be a good idea to mount a 36 tooth trigger wheel in case I want to add a new injection/ignition system later.


Although I can't add to the discussion about how the injection and ignition systems work, I can comment on resistors in the system. If you place resistors in series in a circuit, they don't add linearly. They add like 1/R = (1/R1) + (1/R2).

So if you have a 2.5 and a 3 ohm in series, the total resistance will be 1.36 ohms.

Just sayin' (IMG:style_emoticons/default/smile.gif)


Actually you have that backwards. Resistors in series DO add.
Resistors in parallel use the equation you posted above.

And having a capacitor installed across the coil will cause it to open slower because some of the current that would have gone into the solenoid (inductor) will go into the Cap instead.

And when the drive circuit removes the drive current (PWM or otherwise), the CAP will begin discharging into the inductor providing extra current which would cause the total current to drop less abruptly causing the solenoid to close more slowly.
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Mark Henry
post Oct 8 2016, 09:19 AM
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You guys are really over thinking this stuff....
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Dtjaden
post Oct 8 2016, 09:29 AM
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QUOTE(MikeM @ Oct 8 2016, 08:08 AM) *

QUOTE(Bartlett 914 @ Oct 8 2016, 08:29 AM) *

Good Job. I used to take my 914 on long trips regularly. I was doing 20K in the summer months alone. This is the way these cars should be used. I really loved it. I think next year I will start this again

Sounds like a great trip. The east coast is fantastic!!
Mike

(IMG:style_emoticons/default/agree.gif)
The Megasquirt Hardware manual, page 53, the last section on the page explains ALL that you need to know. Just follow their recommendation and all will be good!
From the manual:
4.10.2.4 Low impedance injectors - Injector Resistors
This method has been used by many OEMs as a simple approach to driving low-z injectors. The installer has the option of installing a power resistor (typically with a 20 to 25 watt rating) in series with each injector (in effect converting them to high impedance.)
The series resistors will slow down the opening of the injector slightly, so it is suggested that the resistance of the resistors be kept to a minimum but staying within the 14A limit of each injector channel. One resistor must be used for each injector - do not try to share resistors.

For typical 2.5ohm low impedance injectors, the following resistances can be used

2 Injectors per channel - 4.7 ohm resisters per injector

Following this recommendation is a photo and a wiring pictorial. Follow this and you will not go wrong.

In the 914 World we may think that Megasquirt is new technology t has been around for over 15 years. The Megasquirt developers DO know what they are doing.
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Dtjaden
post Oct 8 2016, 09:31 AM
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QUOTE(stugray @ Oct 8 2016, 08:15 AM) *

QUOTE(Phoenix914 @ Oct 8 2016, 08:37 AM) *

Since my engine is out, I'm thinking it would be a good idea to mount a 36 tooth trigger wheel in case I want to add a new injection/ignition system later.


Although I can't add to the discussion about how the injection and ignition systems work, I can comment on resistors in the system. If you place resistors in series in a circuit, they don't add linearly. They add like 1/R = (1/R1) + (1/R2).

So if you have a 2.5 and a 3 ohm in series, the total resistance will be 1.36 ohms.

Just sayin' (IMG:style_emoticons/default/smile.gif)


Actually you have that backwards. Resistors in series DO add.
Resistors in parallel use the equation you posted above.

And having a capacitor installed across the coil will cause it to open slower because some of the current that would have gone into the solenoid (inductor) will go into the Cap instead.

And when the drive circuit removes the drive current (PWM or otherwise), the CAP will begin discharging into the inductor providing extra current which would cause the total current to drop less abruptly causing the solenoid to close more slowly.


(IMG:style_emoticons/default/agree.gif)
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stugray
post Oct 8 2016, 09:31 AM
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QUOTE(Mark Henry @ Oct 8 2016, 09:19 AM) *

You guys are really over thinking this stuff....


That's why I was trying to stay out of it but:

(IMG:http://www.914world.com/bbs2/uploads_offsite/imgs.xkcd.com-10819-1475940661.1.png)

It's like when my teenager asks; Dad can you help me with my math? And I realize 40 minutes in that I probably should have tried to explain it without the Calculus....
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McMark
post Oct 8 2016, 10:56 AM
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Seriously. Low impedance injectors need a resistor pack. 1.8 engine had them. Use one of those. Done.
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Mblizzard
post Oct 8 2016, 01:10 PM
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QUOTE(McMark @ Oct 8 2016, 08:56 AM) *

Seriously. Low impedance injectors need a resistor pack. 1.8 engine had them. Use one of those. Done.


Never seen one of those. Anyone have photo?
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Mblizzard
post Oct 8 2016, 01:10 PM
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I know some of the discussion may seem trivial to some but this is how we learn.

Agree or disagree. Not really relevant. This will be a long process for me and I will always welcome input. Some of us may learn a few things along the way. Thanks to everyone for helping out.
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N_Jay
post Oct 8 2016, 01:12 PM
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QUOTE(stugray @ Oct 8 2016, 10:15 AM) *



And having a capacitor installed across the coil will cause it to open slower because some of the current that would have gone into the solenoid (inductor) will go into the Cap instead.


I did not say across the coil, I said across the RESISTOR.
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Phoenix914
post Oct 8 2016, 01:17 PM
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QUOTE(stugray @ Oct 8 2016, 11:15 AM) *

QUOTE(Phoenix914 @ Oct 8 2016, 08:37 AM) *

Since my engine is out, I'm thinking it would be a good idea to mount a 36 tooth trigger wheel in case I want to add a new injection/ignition system later.


Although I can't add to the discussion about how the injection and ignition systems work, I can comment on resistors in the system. If you place resistors in series in a circuit, they don't add linearly. They add like 1/R = (1/R1) + (1/R2).

So if you have a 2.5 and a 3 ohm in series, the total resistance will be 1.36 ohms.

Just sayin' (IMG:style_emoticons/default/smile.gif)


Actually you have that backwards. Resistors in series DO add.
Resistors in parallel use the equation you posted above.

And having a capacitor installed across the coil will cause it to open slower because some of the current that would have gone into the solenoid (inductor) will go into the Cap instead.

And when the drive circuit removes the drive current (PWM or otherwise), the CAP will begin discharging into the inductor providing extra current which would cause the total current to drop less abruptly causing the solenoid to close more slowly.


Thank you sir, may I have another!

(IMG:style_emoticons/default/headbang.gif)

Brain not wired right this morning.
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jcd914
post Oct 8 2016, 03:08 PM
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QUOTE(Mblizzard @ Oct 8 2016, 12:10 PM) *

I know some of the discussion may seem trivial to some but this is how we learn.

Agree or disagree. Not really relevant. This will be a long process for me and I will always welcome input. Some of us may learn a few things along the way. Thanks to everyone for helping out.


A couple points to bear in mind as you are soaking in all the info you can and as you decide what and how you are going to proceed.

Low impedance injectors with resistor packs have been used by several manufacturers and yest this slows the injector opening but it is insignificant, especially if you start think about the speed of the analog D-jet/L-jet systems compared to the speed of a digital Mega/Micro Squirt system.

Keep it simple, there are a lot of people that have set up Mega/Micro Squirt systems that are not engineers or techo wizards. Don't over complicate a setup, it is not necessary.

If you are going with MicroSquirt rather that MegaSquirt, be sure to reference the MicroSquirt manual for specifications. There have been a few thing referenced in this thread that were from the MegaSquirt manual. The 2 systems are very similar and many thing apply to both but some things do not.

The specific reference that I know is different is the amperage rating for the injector drives. MegaSquirt has a high amperage rating on the injector drivers than does MicroSquirt.
The MicroSquirt drivers/heatsinks are smaller to fit in the smaller ECU housing and can only handle 5 amps (per the MicroSquirt manual)

I don't know how or what other differences exist and my focus has been on learning about MegaSquirt, since the car I bought had a MegaSquirt equipped engine. It is not up and running yet, so I am just studying the system for future tinkering.

Good luck
Jim
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cgnj
post Oct 10 2016, 11:50 AM
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Hi,
waited till I had something of value to add.Grabbed a few ac pulleys and I don't see any cranktrigget that uses the locating pin will not support the stock ac pulley.

So your AC choices are trigger wheel in distributor, Mark or thedubshop trigger wheel, plus this from dlee http://www.914world.com/bbs2/index.php?sho...=192917&hl=

Carlos
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Mblizzard
post Oct 10 2016, 12:23 PM
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QUOTE(cgnj @ Oct 10 2016, 09:50 AM) *

Hi,
waited till I had something of value to add.Grabbed a few ac pulleys and I don't see any cranktrigget that uses the locating pin will not support the stock ac pulley.

So your AC choices are trigger wheel in distributor, Mark or thedubshop trigger wheel, plus this from dlee http://www.914world.com/bbs2/index.php?sho...=192917&hl=

Carlos


Just heard from Mario. No go on the mini cam. it uses a crank trigger.

Will likely use my stock dizzy, locked out on advance, with Petronix to get signal to ECU.

Made some progress. Wired in MAP sensor yesterday.
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N_Jay
post Oct 10 2016, 04:54 PM
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Is anyone using a MAF sensor or an O2 sensor with there MS setup?

If so, which ones, mounted how?
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Mueller
post Oct 10 2016, 10:04 PM
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QUOTE(N_Jay @ Oct 10 2016, 03:54 PM) *

Is anyone using a MAF sensor or an O2 sensor with there MS setup?

If so, which ones, mounted how?


No need for a MAF, you use the map sensor.

Pretty much any newer WB02 sensor, the manuals should have the recommended and proven units. (buy a new one, don't cheap out on used)

http://www.megamanual.com/PWC/

RTFM (IMG:style_emoticons/default/smile.gif)
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jd74914
post Oct 11 2016, 05:57 AM
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QUOTE(Mueller @ Oct 10 2016, 11:04 PM) *

QUOTE(N_Jay @ Oct 10 2016, 03:54 PM) *

Is anyone using a MAF sensor or an O2 sensor with there MS setup?

If so, which ones, mounted how?


No need for a MAF, you use the map sensor.

Pretty much any newer WB02 sensor, the manuals should have the recommended and proven units. (buy a new one, don't cheap out on used)

http://www.megamanual.com/PWC/

RTFM (IMG:style_emoticons/default/smile.gif)


14point7 makes some very reliable, low cost O2 sensor controllers. I've had better luck with them than Innovate products over the last few years and they are much cheaper to boot! (IMG:style_emoticons/default/smile.gif)

I would recommend getting a Spartan 2 over an Innovate LC/LM/1/2/etc. or any of the AEM products.

http://www.14point7.com/products/spartan-lambda-controller-2
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