MicroSquit Conversion, Giving this a try Options

[Mblizzard]

Maybe I am not picturing it correctly, but how does it go between the crank and fan and NOT space the fat out further?

There is a thick washer under the fan that gets replaced. (IMG:style_emoticons/default/smile.gif)

And that is my issue. That washer has already been replaced by the existing pulley for the AC. So I am not sure that I can get everything in there and have it aligned correctly.

[Mblizzard]

Ok let’s be clear. I am not no wiring expert! But as I understand things the micro squirt controls the injectors by providing ground. Meaning the controller switches ground on an off as needed to fire the injectors. Because I have low impedance injectors I have to use resistors. Below is the guidance from the manual on how to wire.

Based on this it shows the resistors on the controller side which is ground. (IMG:style_emoticons/default/WTF.gif)

This can’t be correct can it? Especially when it stats than an individual resistor is required for each injector.

The resistors have to go on the 12v wire don't they?

The order of devices in series is immaterial.

Question, how much voltage and current at are the injectors designed for?
What is the current the MS is designed to sink?

Lets say the injector resistance is around 2.5 Ohms and I am adding another 3 Ohms so that would be about 2 amps based on 12V.

[N_Jay]

Ok let’s be clear. I am not no wiring expert! But as I understand things the micro squirt controls the injectors by providing ground. Meaning the controller switches ground on an off as needed to fire the injectors. Because I have low impedance injectors I have to use resistors. Below is the guidance from the manual on how to wire.

Based on this it shows the resistors on the controller side which is ground. (IMG:style_emoticons/default/WTF.gif)

This can’t be correct can it? Especially when it stats than an individual resistor is required for each injector.

The resistors have to go on the 12v wire don't they?

The order of devices in series is immaterial.

Question, how much voltage and current at are the injectors designed for?
What is the current the MS is designed to sink?

Lets say the injector resistance is around 2.5 Ohms and I am adding another 3 Ohms so that would be about 2 amps based on 12V.

So are they looking for 2A at about 6V?

Does anyone have the actual specs?

[cgnj]

[quote name='N_Jay' date='Oct 7 2016, 10:20 AM' post='2408530']
Maybe I am not picturing it correctly, but how does it go between the crank and fan and NOT space the fat out further?[/quote]
I'm certain that it doesn't.

[/quote]
It would seem a Dist trigger wheel could easily have two missing teeth and give you the same trigger as a crank wheel, but could also give you came timing should you ever want sequential FI and/or not run wasted spark.[/quote]
P.S. Not arguing, just asking to learn.
[/quote]

Why would you want to do this? There is a part that already does this. How is the controller going to tell the difference between one missing tooth and another? Is the part your asking about widely available? No. Does it have and acceptable configuration as pictured to repace a crank trigger? No. Let it die. This is what makes barn finds. C.O.T.S is the way to go. (Commercial of the shelf).

Carlos

[N_Jay]

Maybe I am not picturing it correctly, but how does it go between the crank and fan and NOT space the fat out further?

There is a thick washer under the fan that gets replaced. (IMG:style_emoticons/default/smile.gif)

I don't recall, but have not built a Type4 in over 20 years.

I was looking for an easy way with minimum engine rework.

[Dtjaden]

Ok let’s be clear. I am not no wiring expert! But as I understand things the micro squirt controls the injectors by providing ground. Meaning the controller switches ground on an off as needed to fire the injectors. Because I have low impedance injectors I have to use resistors. Below is the guidance from the manual on how to wire.

Based on this it shows the resistors on the controller side which is ground. (IMG:style_emoticons/default/WTF.gif)

This can’t be correct can it? Especially when it stats than an individual resistor is required for each injector.

The resistors have to go on the 12v wire don't they?

The order of devices in series is immaterial.

Question, how much voltage and current at are the injectors designed for?
What is the current the MS is designed to sink?

Lets say the injector resistance is around 2.5 Ohms and I am adding another 3 Ohms so that would be about 2 amps based on 12V.

So are they looking for 2A at about 6V?

Does anyone have the actual specs?

The specs are clearly stated in the appropriate Megasquirt manual, MS2V3 Hardware Manual.
http://www.msextra.com/doc/pdf/MS2V30_Hardware-3.4.pdf
While the specification is 7 amps at 12V (6 volts does not come into this at all) per channel for the output transistors they don't want to drive them at full rating. The manual clearly states the resistor values (both resistance and wattage) and has a wiring pictogram.

As was stated earlier the resistor could be on either side of the injector although their diagram shows the resister installed between the injector and the MS controller. The controller does pull the injector lines to ground. With the resistor values suggested by the Megasquirt manual the current is kept under 2 amps.

Microsquirt is electrically a Megasquirt II version 3

[N_Jay]

Ok let’s be clear. I am not no wiring expert! But as I understand things the micro squirt controls the injectors by providing ground. Meaning the controller switches ground on an off as needed to fire the injectors. Because I have low impedance injectors I have to use resistors. Below is the guidance from the manual on how to wire.

Based on this it shows the resistors on the controller side which is ground. (IMG:style_emoticons/default/WTF.gif)

This can’t be correct can it? Especially when it stats than an individual resistor is required for each injector.

The resistors have to go on the 12v wire don't they?

The order of devices in series is immaterial.

Question, how much voltage and current at are the injectors designed for?
What is the current the MS is designed to sink?

Lets say the injector resistance is around 2.5 Ohms and I am adding another 3 Ohms so that would be about 2 amps based on 12V.

So are they looking for 2A at about 6V?

Does anyone have the actual specs?

The specs are clearly stated in the appropriate Megasquirt manual, MS2V3 Hardware Manual.
http://www.msextra.com/doc/pdf/MS2V30_Hardware-3.4.pdf
While the specification is 7 amps at 12V (6 volts does not come into this at all) per channel for the output transistors they don't want to drive them at full rating. The manual clearly states the resistor values (both resistance and wattage) and has a wiring pictogram.

As was stated earlier the resistor could be on either side of the injector although their diagram shows the resister installed between the injector and the MS controller. The controller does pull the injector lines to ground. With the resistor values suggested by the Megasquirt manual the current is kept under 2 amps.

Microsquirt is electrically a Megasquirt II version 3

I was wondering about the specs on the injectors not the MS.

If you put 13.8v across a 3 ohm resistor in series with a 2.5 ohm injector (we really need the impedance not resistance here) the injector will see about 6.25 V and about 2.5 A

[jcd914]

From a MegaSquirt manual:
"Injectors are either high impedance or low impedance. High impedance injectors (usually about 12-16 ohms) can take a 12 supply directly, without a form of current control. Low impedance injectors (generally below 3 ohms) require some form of current limiting."

From the MicroSquirt manual:
"The fuel injector drives will max out at 5 amps each, enough to drive one low-impedance (or 4 high-impedance) injector per bank. To get everything to fit without lots of heat sinking, MicroSquirt® uses the ST VND5N07 from STMicroelectronics to drive the injectors. This is not a 'peak and hold' driver, but it does clamp the current at 5 amps, so it can be used with one low-impedance injector per bank, however the close time may be a tad higher (or you can use resistors). For up to 4 high-impedance injectors per bank, it should work fine."

So you need to keep the injector amperage below 5 amps per driver.
You can add resistors to the circuits for your original low impedance injectors. The resistors can be added either before of after the injectors it does not matter electrically, they just have to be between the power source and the MicroSquirt control unit.
The 1.8 L-jet 914s used a resistor pack with a single power supply wire connected to all 4 resistors which then supplied a reduced voltage to the injectors. There are other EFI cars (older cars) that also used resistor packs for 4 injectors but whether you could find a resistor pack with the correct resistance, who knows.

MicroSquirt has 2 injector drivers so you can wire and run the injectors in 2 batches just like the OE injectors were paired.

There are calculators online to figure out how much resistance you need to add based on injector resistance and the amperage limit you are after.

Jim

[Dtjaden]

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.

[JamesM]

The DubShop CHT sensor is installed under one of the engine tin screws. It uses the GM sensor element in deferent housing.

If you are going to continue to use the 914 ignition you can't use the DubShop mini cam sync since it replaces the distributor. If you don't want to use a crank trigger wheel (which I strongly reccommend) your only option is using coil/points triggering.

Without using an ICV it will be difficult if not impossible to get hands off (really foot off) start up. You will need to use the accelerator for the first few minutes to keep the engine running until it reaches operating temperature.

The mini cam is the next stage. Starting with the coil for the tac signal for the fuel only stage.

I understand that there might be some variance in the use of the dizzy timing approach but I guess I just don't know enough about the crank trigger to determine why it would be better.

My goals are a low cost, dependable, and drivable system. Not trying to see great HP gains just a reliable system.

Can you point me to an ICV?

I trigger using a Pertronix unit inside a distributor with a locked out advance mechanism. a 36 tooth wheel would be more accurate but I have had no problem triggering timing from the dizzy. Output is to a Mallory highfire 6-al.

I also run a stock CHT. The biggest downside is that the stock CHT grounds through the engine rather than back through the ECU common ground. It adds an extra step in that you need to set the curve in the MS tune to match the sensor. Two wire sensor should in theory have less chance of interference.

ICVs are not mandatory, especially if you only drive in warm climates. I am using a stock 1.8 CSV which is not tuneable via the MS but provides the same function of allowing more air in when cold. If you want to go with a full stepper motor ICV I believe (dont quote me on this one) the ICV from a water-cooled vanagon will work.

It runs pretty good https://youtu.be/kk9_5ewkIOU

[N_Jay]

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?

[Mark Henry]

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?

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.

[Mblizzard]

From a MegaSquirt manual:
"Injectors are either high impedance or low impedance. High impedance injectors (usually about 12-16 ohms) can take a 12 supply directly, without a form of current control. Low impedance injectors (generally below 3 ohms) require some form of current limiting."

From the MicroSquirt manual:
"The fuel injector drives will max out at 5 amps each, enough to drive one low-impedance (or 4 high-impedance) injector per bank. To get everything to fit without lots of heat sinking, MicroSquirt® uses the ST VND5N07 from STMicroelectronics to drive the injectors. This is not a 'peak and hold' driver, but it does clamp the current at 5 amps, so it can be used with one low-impedance injector per bank, however the close time may be a tad higher (or you can use resistors). For up to 4 high-impedance injectors per bank, it should work fine."

So you need to keep the injector amperage below 5 amps per driver.
You can add resistors to the circuits for your original low impedance injectors. The resistors can be added either before of after the injectors it does not matter electrically, they just have to be between the power source and the MicroSquirt control unit.
The 1.8 L-jet 914s used a resistor pack with a single power supply wire connected to all 4 resistors which then supplied a reduced voltage to the injectors. There are other EFI cars (older cars) that also used resistor packs for 4 injectors but whether you could find a resistor pack with the correct resistance, who knows.

MicroSquirt has 2 injector drivers so you can wire and run the injectors in 2 batches just like the OE injectors were paired.

There are calculators online to figure out how much resistance you need to add based on injector resistance and the amperage limit you are after.

Jim

Thank you sir. That is most helpful! First of many questions solved.

[Mblizzard]

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.

Spot on. measure 4 tonight. All between 2.5 and 2.6.

[Dtjaden]

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.

[Dtjaden]

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.

Spot on. measure 4 tonight. All between 2.5 and 2.6.

So all you need to do is use 4.7 ohm resistors as specified in the Megasquirt/Microsquirt documentation.

[Dtjaden]

Blizzard - what are you doing for A/C on your car. I am interested.

[Mblizzard]

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.

Spot on. measure 4 tonight. All between 2.5 and 2.6.

So all you need to do is use 4.7 ohm resistors as specified in the Megasquirt/Microsquirt documentation.

Glad I just got in a set of 3 ohm resistors! Guess I will be buyin more!

[Mblizzard]

Blizzard - what are you doing for A/C on your car. I am interested.

Not clear on this question. Granted I am on my second glass of wine. Or is that second bottle? Who's counting? (IMG:style_emoticons/default/beer3.gif)

I have a dealer installed DPD system. On the next engine drop I am replacing the York compressor with a Sanden. But other than that I am just running the deal installed set up.

[Mblizzard]

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.

Spot on. measure 4 tonight. All between 2.5 and 2.6.

So all you need to do is use 4.7 ohm resistors as specified in the Megasquirt/Microsquirt documentation.

Glad I just got in a set of 3 ohm resistors! Guess I will be buyin more!

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.