Megasquirt Info Thread

Whizbang · 04-04-2009, 02:33 PM

Alright so starting tonight or tomorrow im starting my Megasquirt wiring. Figured i would give out some general info as i work through it all. Might come in handy for some others. For starters, i am only using it for fueling, so some of the things i do would not apply if you wanted to have ignition control.

Below are two similiar wiring diagrams. One is specifically for the Rx7 running the CAS, the other is if you are planning on using the Dizzy. I am using the dizzy with a CDI box to make the signal usable. Now, if you are planning on using ignition control, you can not just use the "tach out" from the CDI as a signal for the megasquirt. But for fueling, it will work just fine.

Whizbang · 04-04-2009, 02:36 PM

As far a sensors go, there are several ways you go about things. There is plenty of info on the megasquirt web forums related to sensors, but for the Rx7 almost everything is useable. The IAT (intake air temp) sensor will read off by 10 degrees. You can use a resister and figure it back to correct reading, but i just elected to drill and tap for using a GM sensor (which reads true). Mostly because i have an after market manifold and i have to drill and tap for it anyway.

The TPS, coolant temp sensor, etc will all work with the megasquirt.

NoDOHC · 04-04-2009, 10:21 PM

How about the stock MAP sensor, will it work? Are you using an S5 TPS?

TheDriver216 · 04-04-2009, 10:38 PM

Mega squirts come with a 2bar map with most of the kits... i have mine with a 4bar... you can use a gm 3bar as well...

RotaryProphet · 04-04-2009, 11:41 PM

Quote:

Originally Posted by TheDriver216

Mega squirts come with a 2bar map with most of the kits... i have mine with a 4bar... you can use a gm 3bar as well...

The normal units come with a 2.5 bar (~22psi boost) map sensor. 3 and 4 bar units are also available in the same form factor.

Also, it should be noted that the top wiring harness (for using the stock cas) requires internal mods to the Megasquirt to fire spark. It's also possible to build a second VR input sensor and use both inputs on the stock unmodified CAS.

vex · 04-04-2009, 11:53 PM

My question is however: how many inputs/outputs can you have max?

RotaryProphet · 04-05-2009, 10:21 AM

Quote:

Originally Posted by vex

My question is however: how many inputs/outputs can you have max?

Just two fuel injection outputs, but up to 4 spark outputs, plus a bunch of other random stuff. Unfortunately, a lot of the other stuff requires mods to the board.

vex · 04-17-2009, 08:32 PM

Quote:

Originally Posted by RotaryProphet

Just two fuel injection outputs, but up to 4 spark outputs, plus a bunch of other random stuff. Unfortunately, a lot of the other stuff requires mods to the board.

So there's no way to increase the total input/output count? say, have 4 spark out, 4 inj out, 18 aux out, bunch of inputs, etc.? Could I do it if I soldered in some more components or something?

RotaryProphet · 04-18-2009, 12:57 PM

Quote:

Originally Posted by vex

So there's no way to increase the total input/output count? say, have 4 spark out, 4 inj out, 18 aux out, bunch of inputs, etc.? Could I do it if I soldered in some more components or something?

Aux outputs and inputs can be had by using the general purpose IO board, but not for spark or injector outputs.

There's also a router board that lets you do sequential fuel/spark control.

Both of the boards are still in beta testing, and both talk to the MS unit via the CAN bus.

Being a programmer myself, I've been working on various stuff of my own. My overall project is a modular ECU, but I've been testing with smaller scale projects. Right now on my desk I have a little computer designed to read two MAP sensors and control four actuator outputs designed to control a sequential turbo setup & electronic wastegate.

I might be in a position to offer aftermarket programmable sequential control soon, but a full ECU is a long way off.

vex · 04-18-2009, 01:45 PM

Quote:

Originally Posted by RotaryProphet

Aux outputs and inputs can be had by using the general purpose IO board, but not for spark or injector outputs.

There's also a router board that lets you do sequential fuel/spark control.

Both of the boards are still in beta testing, and both talk to the MS unit via the CAN bus.

Being a programmer myself, I've been working on various stuff of my own. My overall project is a modular ECU, but I've been testing with smaller scale projects. Right now on my desk I have a little computer designed to read two MAP sensors and control four actuator outputs designed to control a sequential turbo setup & electronic wastegate.

I might be in a position to offer aftermarket programmable sequential control soon, but a full ECU is a long way off.

Please keep us posted on this. I don't mind having to write code, but writing machine code is a new territory for me so I may not be in a good position to help in any sorts, but knowing that it is possible to control aux inputs/outputs is good knowledge, as is the ability to do sequential fuel/spark is a big plus to me and may cause me to sway my previous decisions on ecu.

jamespond24 · 04-05-2009, 11:39 AM

Does the CAS only need the Ne- & Ne+? What about the G- & G+?

RotaryProphet · 04-05-2009, 04:20 PM

Quote:

Originally Posted by jamespond24

Does the CAS only need the Ne- & Ne+? What about the G- & G+?

To use the CAS on the standard (unmodified) MS board requires grinding two opposing teeth off of the 20 tooth wheel in the CAS, then disregarding the 2 toothed wheel.

The "better" solution is to build a second VR input circuit on the MS board, and use both wheels in the CAS without modification. Honestly, either way works just fine in most circumstances.

jamespond24 · 04-05-2009, 10:52 PM

Ok I bought an MS1 V2.2 and I'm having problem finding the right software and firmware. I tried the MT 2.25p3 and couln't get the COM to work on my laptop.

RotaryProphet · 04-06-2009, 08:36 AM

Quote:

Originally Posted by jamespond24

Ok I bought an MS1 V2.2 and I'm having problem finding the right software and firmware. I tried the MT 2.25p3 and couln't get the COM to work on my laptop.

www.diyautotune.com has a software section that should be able to help you out. They have a big package with pretty much anything on it.

Whizbang · 04-05-2009, 11:57 PM

im still confused on how to run the injectors. since it has two outs, would i have the injectors that are firing at the same time run one rotor at a lower pulse width?

04-04-2009, 02:33 PM	#1
Whizbang Respecognize! Join Date: Jul 2008 Location: Δx = ħ/2Δp Posts: 3,190 Rep Power: 21	Megasquirt Info Thread Alright so starting tonight or tomorrow im starting my Megasquirt wiring. Figured i would give out some general info as i work through it all. Might come in handy for some others. For starters, i am only using it for fueling, so some of the things i do would not apply if you wanted to have ignition control. Below are two similiar wiring diagrams. One is specifically for the Rx7 running the CAS, the other is if you are planning on using the Dizzy. I am using the dizzy with a CDI box to make the signal usable. Now, if you are planning on using ignition control, you can not just use the "tach out" from the CDI as a signal for the megasquirt. But for fueling, it will work just fine. __________________ For current updates and event coverage check out Follow on Twitter! @WhizbangRally Whizbang Rally's Webpage \| Facebook

04-04-2009, 02:36 PM	#2
Whizbang Respecognize! Join Date: Jul 2008 Location: Δx = ħ/2Δp Posts: 3,190 Rep Power: 21	As far a sensors go, there are several ways you go about things. There is plenty of info on the megasquirt web forums related to sensors, but for the Rx7 almost everything is useable. The IAT (intake air temp) sensor will read off by 10 degrees. You can use a resister and figure it back to correct reading, but i just elected to drill and tap for using a GM sensor (which reads true). Mostly because i have an after market manifold and i have to drill and tap for it anyway. The TPS, coolant temp sensor, etc will all work with the megasquirt. __________________ For current updates and event coverage check out Follow on Twitter! @WhizbangRally Whizbang Rally's Webpage \| Facebook

04-04-2009, 10:21 PM	#3
NoDOHC The quest for more torque Join Date: Sep 2008 Location: Sheboygan, Wisconsin Posts: 855 Rep Power: 17	How about the stock MAP sensor, will it work? Are you using an S5 TPS? __________________ 1986 GXL ('87 4-port NA - Haltech E8, LS2 Coils. Defined Autoworks Headers, Dual 2.5" Exhaust (Dual Superflow, dBX mufflers) 1991 Coupe (KYB AGX Shocks, Eibach lowering springs, RB exhaust, Stock and Automatic)

04-04-2009, 11:53 PM	#6
vex RCC Loves Me Not You Join Date: Jul 2008 Location: Influx. Posts: 2,113 Rep Power: 20	My question is however: how many inputs/outputs can you have max? __________________ The Official FC Radiator Thread My Project Thread: Cerberus CCVT Virginia Rotary Group

04-05-2009, 11:57 PM	#15
Whizbang Respecognize! Join Date: Jul 2008 Location: Δx = ħ/2Δp Posts: 3,190 Rep Power: 21	im still confused on how to run the injectors. since it has two outs, would i have the injectors that are firing at the same time run one rotor at a lower pulse width? __________________ For current updates and event coverage check out Follow on Twitter! @WhizbangRally Whizbang Rally's Webpage \| Facebook

04-04-2009, 10:38 PM	#4
TheDriver216 Rotary Fanatic Join Date: Feb 2008 Location: Cleveland, Ohio Posts: 159 Rep Power: 18	Mega squirts come with a 2bar map with most of the kits... i have mine with a 4bar... you can use a gm 3bar as well...

04-05-2009, 11:39 AM	#11
jamespond24 Rotary Fanatic Join Date: Feb 2008 Posts: 157 Rep Power: 18	Does the CAS only need the Ne- & Ne+? What about the G- & G+?

04-05-2009, 10:52 PM	#13
jamespond24 Rotary Fanatic Join Date: Feb 2008 Posts: 157 Rep Power: 18	Ok I bought an MS1 V2.2 and I'm having problem finding the right software and firmware. I tried the MT 2.25p3 and couln't get the COM to work on my laptop.