MoTeC Global Forum

Hi i have a M800 ecu which l use for my SBC drag truck. I have recently changed the engine for a GM LS engine. On the original SBC I used a MSD crank trigger system with four rotating magnets on the front pulley. This had a 2 pin connector plug (orange and blue wires) Now on the LS I have the 24x black sensor which is 3 pin. How to I wire the new sensor to work with the M800 system please.
Thanks Kev

Hi Kev,

The attached files should be able to assist in the wiring and setup of this sensor.

Stephen
I know I must be appearing stupid but I have some questions about the above transplant. I have wired the 3 wire crank sensor and now have some settings to alter. What values do I put in the following boxes?
1- Ref/ Sync mode.
2- Crank Ref Teeth.
3-Tooth ratio.
4-Crank index pos.
5-Ref sensor type.
6-Ref sensor edge pol.
7-Ref trigger voltage.
8-Sync sensor type.
9-Sync sensor edge pol.
10- Sync sensor voltage.
I have an idea on some of these but am not 100 percent sure.
To recap the engine is a 05 5.3 LS with std GM sensors and a 24x reluctor wheel.
Thanks for any help you can give me.
Kev

Hi Kev,

The attached document will be able to assist you with this.

Stephen,
Thanks for your help it was most useful. The next issue is the firing order. I have changed the order in the ECU easily enough and pressed R and saved changes. When testing the firing order is the old small block order not what I have changed it to. Do I have to physically rewire the injectors to change the order. Is there not a way the ECU can alter this.
Thanks Kev

Hi Kev,

Mx00 series ECU's are wired in firing order, the firing order parameter in the ECU Manager does not change the firing order of the injectors or coils, it provides a visual link in the Manager to which output is wired to which cylinder, so that if you need to add a trim to Cylinder 3 (as an example) you do not have to remember that it is the 7th to fire so you need to add the trim to Injector output 7 to do this.

If you need to change the firing order of the injectors and/or coils, it is typically easier to do so by repinning the connector end of the loom.

kevdachev wrote:Stephen
I know I must be appearing stupid but I have some questions about the above transplant. I have wired the 3 wire crank sensor and now have some settings to alter. What values do I put in the following boxes?
1- Ref/ Sync mode.
2- Crank Ref Teeth.
3-Tooth ratio.
4-Crank index pos.
5-Ref sensor type.
6-Ref sensor edge pol.
7-Ref trigger voltage.
8-Sync sensor type.
9-Sync sensor edge pol.
10- Sync sensor voltage.
I have an idea on some of these but am not 100 percent sure.
To recap the engine is a 05 5.3 LS with std GM sensors and a 24x reluctor wheel.
Thanks for any help you can give me.
Kev

I'd think Motec should have a base map file for a standard old LS engine that should get you started without needing to do too much individual settings.

Stephen,
Had the loom altered by a Motec dealer fitted it and the truck started, but I have a few issues
1- Engine is running extremely rich, punching out black smoke, will the engine not follow the air/fuel ratios from before?
2-When the map sensor is connected to a vacuum source the engine revs up on its own.
3-With the engine running the diagnostic errors page show the ref/sync syncronised yet on a ref/sync capture I am only seeing the green square trace for ref and no yellow sync trace.
Thanks for your help again.
Kev

Hi Kev,

1, Are you using the same map as from the old engine? If so, you will need to retune the engine. There is some scope within the closed loop function if you have a lambda sensor installed and the closed loop enabled to adjust the fuelling, but this still needs for the tune to be within around 10% of the target. The M800 uses a mS based fuel map, so it is just going to be driving the injectors at that pulse width, not knowing how much fuel is actually being delivered.

2, I would need to see more data on this.

3, That is correct for this RefSync mode and it's wiring. As the Crank trigger is wired into both the Ref and Sync inputs, these are the only ones captured and they will overlay on top of each other. The RefSync Capture does not look at the Digital inputs that the Sync is wired into.