Magnum ignitons on MS-II step 2: Camshaft Position Sensor input & wheel decoder

[Matt Cramer]

I've taken another look through the manual - these mods are not particularly easy to do in the 1.0 release family, so I'll make this for 2.0 beta codes and higher.

After getting a clear RPM reading from the crank trigger, the next thing to check is the camshaft (distributor) trigger. It's a 5 volt Hall effect sensor.

There's one thing that complicates this one: The MS-II V3.0 is running out of inputs if you're using our standard harness. You'll probably want the stepper IAC wires, so the only pins you can grab are the spare pins (not in the harness, but you can add a wire there) or you can disable the on/off fast idle output. Your choice. If you have a V3.57, you can use the DB15 connector here.

If you're using the spare input pins, they're labeled SPR1 through SPR4. These correspond to pins 3 through 6 on the DB37. Follow these steps:

1. Connect the SPR pin of your choice to JS10.
2. Split the output of the camshaft position sensor so it goes to both the appropriate spare input on Megasquirt and the stock PCM.

If you're using the fast idle pin 30 as an input, follow these steps:

1. Remove D8 and Q4. (If you're assembling from a new unit, just leave them out along with R19, Q20, and R39).
2. Use the hole on the banded end of D8 as your input pin. Connect this to JS10.
3. Split the output of the camshaft position sensor so it goes to both the appropriate spare input on Megasquirt and the stock PCM.

Next we set up the basic wheel decoder. We won't worry about trigger angles yet as we're just using this as an RPM input for now.

1. Change it back to 8 cylinders (it was set to 16 in step 1 testing of our experiment).
2. Under Basic / Advanced user, enable spark output if you have not already done so.
3. Under Tach Input / Ignition Settings, make the following changes:

Ignition Input Capture: Falling Edge
Spark Mode: Toothed Wheel
Spark Output: Going High (Inverted)
Number of Coils: Single Coil
Spark A output pin: D14

Burn these to the ECU.
4. Under Trigger Wheel Settings, make the following changes:

Trigger wheel arrangement: Dual wheel
Trigger Wheel Teeth: 8
Missing Teeth: 0
Tooth #1 Angle: 0 (this is going to be changed later)
Wheel speed: Crank wheel
Second trigger active on: Rising and Falling

Burn these settings to the ECU.

You'll need to turn the ECU off and back on again after making these changes.

Check to be sure you are getting RPM.

Next step after this is found to work will be to set up the actual trigger angles.

[4x4 98]

So if we have there steps done we can fully adjust the timnig of the ignition with the MS and not with the stock ECU and we will get no MIL??

I am not using the stepper motor, I going to use injectors for propane with the peak and hold boards, so wich one I can use the best??

Is it possible to have dual tables, one for propane and one for gas??

Thanks and greetings,


Erik.

[Matt Cramer]

Once all these steps are done the Megasquirt can control fuel and ignition. This step still ends with fuel only control and is for completing having the Megasquirt read the factory sensors. Once that's done you will need to find the trigger angle and then set it for spark control.

The MS2/Extra code does have a table switching setup, but the peak and hold drivers aren't something I have any experience with. Same goes for whether the stock ECU will throw any codes - the steps are, so far, incomplete.

[4x4 98]

Thanks for the reply Matt.

The peak and hold boards only control the injectors the timing is controlled by MS.

They must be used if you use injectors wilth a low internal resistor or else the MS will be dying because of the high amperage.

I am not going to use the stepper IAC so wich wire or input I need for it?

Thanks and greetings,

Erik.

[Matt Cramer]

We've had customers run LPG injectors off the Megasquirt without peak and hold boards - you can use the flyback circuits, which are on the V3.0, instead.

[4x4 98]

Done a little work today, put al the wires in the truck had not enough time to connect them.

On the original ECU the pin for TPS is A23 from the black connector.

The cranckshaft position sensor is A8 from the black connector

Tonight I am going further and let you know.


Greetings,


Erik.

[4x4 98]

hello Matt,

I have a qeustion, if we have a clear signal from the cranck sensor do we need to use the camsensor?

Greetings,


Erik

[mtlcafan79]

Yes. You need two wheels to sync so that it knows when it's on the compression stroke.

[Matt Cramer]

hello Matt,

I have a qeustion, if we have a clear signal from the cranck sensor do we need to use the camsensor?

Greetings,


Erik

If the 5.9 had a four tooth crank wheel, it would have been possible to go without cam sensor input since each tooth would correspond to a spark event. However, there are eight teeth on the crank wheel, so only half the teeth correspond to a spark event and the other half are used for detecting changes in RPM. You need the cam sync to tell which is which.

[4x4 98]

Ok I have been wiring(AGAIN) today.

I want to use pin 1 on the db37 but it wont work because I have the original MS wiring harness wher I can put no extra inputs on, so I must use one wire off the IAC stepper wires.

The wires on the stock ECU :

Camshaft sensor : A18 in the Black connector on the ECU
IAT : A15 in the Black connector on the ECU
CLT : A16 in the Black connector on the ECU
TPS : A23 from the black connector on the ECU
CPS : A8 from the black connector on the ECU

[4x4 98]

I have done the modifications on the MS

I have used pin 3 as the second input for the cam trigger and connected it to js10.

I have a RPM reading now but it is only 200 rpm.

The engine wont start again with the MS connected.

I use the ms now only for reading the sensors : IAT, CLT, TPS, O2 and the CPS and the cranck.

So what I am doing wrong?

Thanks and greetings,


Erik.

[mtlcafan79]

Have you logged your starting attempts yet? I always log when I'm trying something new. MegaLogViewer will show you tons of information. I had several occasions where the logs showed me what I was doing wrong.

Have you tried posting on msefi.com or msextra.com yet? Post up a .msq file and people can look that over for you to make sure you have that part correct.

[Matt Cramer]

It actually doesn't sound like you are doing something wrong at this point: It appears the PCM doesn't like sharing its sensors. So you will need to get the spark control running before it fires up. I'll try to get the how-to on that section written up ASAP.

[4x4 98]

I am not familiar with megalogviewer, how do I use it?

Can I use it with only the inputs I use?

Thanks and greetings,

Erik.

[4x4 98]

I have tried to make a logfile :

http://img.photobucket.com/albums/v140/activate1/test.png

Let me know what you think.


Thanks and greetings,


Erik.

[Matt Cramer]

It looks like it's working correctly so far. We'll just need to get on to the directions for adding spark control. Today's a bit busy but I will try to have them by the end of the week.

[4x4 98]

Hello Matt,

I hope it is working fine so far, the starnge thing is when the engine is running on the stock ECU and I plug the db37 in the engine dying immediatly, I have only the inputs connected no ignition or injectors, thats the strange thing for me...

I will send you the files.

Thanks and greetings,


Erik.

[4x4 98]

Hello Matt?

Already written step 3??

Thanks and greetings,


Erik.