Megasquirt info

The last thing i need to figure out is how the stock ignitor is wired up. Then can hopefully start it.

In the FSM, EF & EC Page 92, Ignition Signal

The stock (88t) ignitor has L, G/B, and B wires.

L = 12v when car is on (IGN)
G/B = Trigger, what you connect MS pin 36 to
B = Ground

Ok, i understand that. i guess i should have re-worded what i was trying to say. Using Pin 36 and the stock ignitor requires NO mods to the ecu correct? Only if i was trying to use the internal ignitor i have to make sure R57(i think) is not solderd in.

Thanks so much for your Help Bloz up. Its a little rought when theres only a handful of people using this computer on this engine. Hopefully i get all the settings right and such so it can run.

I have never used R57. I used my MS with the OE ignitor, and with the VB921/BIP373 (I blew the VB up). As long as you don't have R57 installed, you can use either. You can also have the VB/BIP installed (if it already is) and use the OE ignitor, as long as you jumper JS10 to IGN.

Be careful of your MegaTune settings. For the VB/BIP/OE driver, coil output signal must be "inverted", since it's not firing the coil directly.

http://www.megamanual.com/index.html. This is for MS2.
Wiring the Coil to the High Current Driver

To use the high current driver (with the VB921 dedicated coil driver IC), you must install the high current ignition driver circuit at step#65 of the assembly of your V3 main board.

Make sure you did not install R57. If you have installed it, remove it (or cut one lead to disable it). R57 is located about 1 inch (25mm) from the DB37, and 1 inch (25mm) from the heat sink. R57 interferes with the signal from the processor to the VB921, so it must be removed, or else your dwell and timing will be wrong.

If you have connected the high current driver, you installed jumpers:

IGBTIN (near the heat sink side of the DB37 on the bottom of the board) to JS10 (under the 40-pin CPU socket on the bottom of the PCB)

IGBTOUT to IGN - near the Heat sink end of the DB37 on the bottom of the PCB (this brings the ignition control signal out on DB37 pin #36)

Wiring the high current circuit to the coil is very easy. You need to supply a switched 12 Volt supply to one side of the coil, to the positive (+) terminal. Use the fuel pump relay for this source, as the coil will then not be powered during a stall, etc. Put a 10 Amp fuse in this wire. The other terminal (negative (-)) is wired to pin 36 of the MegaSquirt® DB37 (this connects to the relay board terminal S5, if you are using the relay board).

http://www.megamanual.com/357/intro.htm For MS3.57

Functionally, the V3.57 board operates identically to the V3 main board with only minor alterations for additional support and functionality.

The differences on the V3.57 board (compared to the V3 thru-hole main board) are:

Majority of the passive devices (capacitors, resistors) and some of the active semiconductor devices (transistors, etc.) have been converted from thru-hole to surface mount. The package size for most devices is 0805 (0.080" x 0.050"), with a few 1206 and 2502 case sizes.

Tach input selection jumper JP1 is now on 0.100 inch header.
-Placing a jumper across positions 1 and 2 enables the variable reluctance (VR) circuit.
-Placing a jumper across positions 2 and 3 enables opto-isolator ("Hall") tach input.

Tach selection jumper J1 is for routing the signal-conditioned tach signal to the processor. Only one jumper is used, the remaining positions are open.
-A jumper on pins 1 - 2 enables the opto-isolator.
-A jumper on pins 3 - 4 enables VR (variable reluctor) operation (non-inverted).
-A jumper on pins 5 - 6 is for an inverted VR signal.

The three front-panel LEDs have been converted to surface mount devices. These cannot be easily viewed through the standard LED end-panel holes, but are easily visible with the case lid off. If front-panel LEDs are desired then the surface mount units are removed and jumper wires installed in place. Also, since the LED drivers are often used for alternative output applications with the spare outputs, there is a new 1K Ohm pull-up resistor connected to the driver transistors, and this connection is available on the PAD1, PAD2, and PAD3 PCB terminals (see schematic for details).

There is a unpopulated pull-up resistor on the tach input line (R57) that can be added to provide bias for Hall sensor and other input sources.

The prototype area has not been implemented on the V3.57 board. Instead there is an unpopulated DB-15 PCB-mount socket (at the same end of the case as the DB-9), with the signals brought out to a series of pads (on 0.100 inch centers). The DB-15 socket is provided to allow I/O connector expansion (it will also require a custom end-plate with an additional cut-out for the DB-15). There are also additional mounting holes located in this area to allow the use of custom expansion boards.

The MAP sensor has been moved higher on the PCB, but still mounts underneath.

The output of the optional ignition driver IGBT (VB921) is hard-connected to pin 36 on the DB-37 connector. No jumpers are required.

The two VR input circuit potentiometers (R52 and R56) have been replaced with a 5-turn surface-mount variant.

The processor pin jumper ports JS0 through JS12 have been brought outside of the processor and arranged in 0.100 inch spacing. There is no change in the pin/jumper name assignments, and these have the same functions as with the V3 thru-hole main board.

The fuel pump and fast idle solenoid outputs are now driven by a power driver IC (Integrated Circuit) from ST, the VNS3NV04D. This device will drive up to 3.5 amps continuous and has a clamp voltage of 40V.

On the fast idle output there is a diode hat minimizes power dissipation on the driver chip for PWM fast idle applications.

The 32 KHz crystal (for MegaSquirt-I) is a surface-mount version

So based on the MS3.57 i shouldnt have to do anything???? I guess the only way to really know is to open the computer up. It says its "built in" so no jumpers are required. Am i reading something wrong?

Ah, I see. I've never messed with the SMT board. Just use the VB/BIP driver in this case. But keep your dwell down. I burned mine out at 2.5ms or so of dwell, so that's apparently too high.

So based on that i should be able to wire the stock resistor up just like you said

L = 12v when car is on (IGN)
G/B = Trigger, what you connect MS pin 36 to
B = Ground

and set the dwell at 2.0 then cross my fingers and go from there

Not quite, since you are using the MS driver, you fire the coil directly off of that.

You need to connect pin 36 to the L (pin 3 on stock ECU) wire, and remove the power transistor. This should be the ground of the coil. Check it with a continuity tester (with everything related disconnected), I am going off memory here.

Setup like this then 36 going to NEG side of coil

Yup, and you can disconnect the OE power transistor.

I use the nissan power transistor, i think is better and stronger.

how would you use the oem transistor on MS3

That's how is appears to me too. Large heatsink, and lasted longer at 2.0ms dwell than the MS VB unit. Haven't tried the BIP unit. Of course, setting my dwell properly using a scope is what I really need to do.