dizwiz24

Or do i need it in place to control gages, CCM, or some other functions ?

Phobos84

With an aftermarket ECU you can control everything but you need to get an ECU that has the I/O that you need. I use a Holley Terminator. I can't for the life of me get the NPN square wave output for the speed signal to work with my Intelitronix speedometer. So I tied it into my VSS (for now). The Megasquirt ECU's have more options as far as how many and what type of I/O than the budget Holley stuff. Of course the Holley Dominator is the king and can make you a margarita at 6000 rpm but it's also over $2K just for the ECU. Holley tuning software is MUCH easier to learn and use. They offer amazing online support for tuning and there are a lot of pros that don't charge that much if you get stuck. Just understand that the lower end Holley ECU's (Terminator and HP) really only have NPN (ground signal) for outputs. So if the gauge you need to run will run off that then your good to go. If not then you may be wiring a basic voltage divide to convert to a positive signal.

If you want to go this route you might want to eliminate the CCM. Not sure if it can work without the factory ECU.

dizwiz24

good info, thank you.

Im trying to figure out if i can completely remove my 1993 ecu box from the
car and use it in another 1993 c4 project car that is missing its ecu.

19corvette91

not without losing some functions.......I added a holley hp ecu to my 1991 but retained my factory ecm in order to retain the speedo. Still working on the air conditioning

Phobos84

So this might be a little nerdy, but in my car I ran out of I/O on my Holley Terminator. So I use a Click PLC to deal with all the I/O needed for my nitrous. When all the conditions are met it activates an input on the Holley telling it to run the progressive nitrous. That way it saves a ton of inputs on the Holley. These controllers are super cheap and fairly simple to program. They can't run an engine. But could very easily run AC or even abs if you wanted. Depending on how you configure one they typically are under $200. Automation Direct sellers them out of Texas. They wrote an article a few years ago about people using them in race cars to monitor suspension load. It could replace the CCM if you wanted to keep all the functions of the car. But you would need to write the program. Lots of online support and tons of YouTube videos that teach the basics.

I've been writing code for plc's for 13 years now. So if you needed help just ask.

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AZSP33D

I have the HP with a 1986 setup (so no CCM, fully functioning dash other than fuel flow which only would work properly with the stock injectors anyway)... but it does have some capability for frequency type inputs and pulse width modulation outputs. No flexible extra hall effect sensor inputs. Can't tell you how to set it up, as I haven't, but here are some details on the inuts and outputs... and you can download software for free and play with it.

The HP has 4 unassigned inputs, at least some of them can be F 5 2 T H G.

The HP also has 4 unassigned outputs, half can be H P+ other half G P-

The Dominator has like 36 inputs and 49 outputs that are flexible for use (not inclding the standard fixed stuff).

What do the designations mean? From the instructions:

9.1 Inputs
There are seven types of inputs that can be configured. The following lists them and reviews wiring recommendations. The designation on the Pin Map (Inputs) is given first, then a description.
1. “H” – Switched 12V or “High Side” input – This input will be triggered when system voltage is applied. Minimum triggering voltage is 4.5V. Do not exceed 24V.
Wiring: Connect up to any voltage source that is desired to trigger this input. See NOTE 1 above.
2. “G” – Switched Ground or “Low Side” input – This input will be triggered when a ground is applied.
Wiring: Connect up to any ground source that is desired to trigger this input. See NOTE 1 above.
3. “5” – 0-5 volt sensor input – Any 0-5 volt sensor input such as a TPS, MAP sensor, pressure transducer, and many others.
Wiring: Wire the signal wire from the 0-5V sensor used into the appropriate pin. Any 0-5V sensor requires a +5V reference voltage and a sensor ground. Each HEFI connector that has 0-5V inputs has its own +5V reference voltage output and sensor ground. These need to be properly wired to each 0-5V sensor used.
It is acceptable to have multiple sensors share the same +5V and ground reference lines. Be sure to solder, heat shrink, etc. wires properly as poor connections will cause for inaccurate or faulty sensor readings.
Do not use +5V reference or ground sources from other controllers or power supplies to support the sensor, or sensor accuracy may be compromised.
4. “2” – 0-20 volt sensor input – Any 0-20 volt sensor input
Wiring: Connect to desired voltage input.
5. “T” – Thermistor temperature input – Most coolant and air temperature sensors are a 2 wire “thermistor” design.
Wiring: Connect to one side of the thermistor device. Connect the other side of the thermistor device to a “Sensor Ground” input pin to the ECU (same pins for a 0-5V sensor).
6. “F” – Frequency or a Digital Speed Input – Designed for a digital voltage input from a speed/rotation sensor. A Hall-Effect sensor is the common sensor used. Voltage range can be 4.5 to 24 volts.
Wiring: A Hall-Effect sensor has 3 wires: Power, Ground, and Signal. Most sensors can be supplied with battery voltage (12V), a few require a 5 volt reference. Check with the specifications of your specific sensor. Although not usually needed with a Hall-Effect sensor, it is always advised to use a shielded/grounded cable to wire them (all three wires can be shielded). The following is advised when wiring a Hall-Effect sensor.
Signal – Run the sensor signal wire into the Pin Mapped channel
Power – Either supply with clean switched power, or if it is not used for another purpose, you can power from Pin P1B-B20 which is a clean 12V power source. If the sensor requires 5 volts, use a +5V reference line.
Ground – It is best to connect to an IPU (Inductive/Magnetic Pickup) or Sensor Ground.
Shield Wire – If using shielded/grounded cable, connect the shield ground wire to the ECU only. It is best to connect it to an IPU ground.
7. “S” – Inductive Speed Input – Designed for an A/C voltage input from a speed/rotation sensor. A magnetic sensor is the common sensor used. The minimum arming voltage is 50 mV.
Wiring: It is highly advised to always use a shielded/grounded cable for any inductive signal. They are very susceptible to noise. An inductive sensor has two wires - a “positive” and “negative”. Connect the positive lead to the “S” input pin that was Pin Mapped. Connect the negative side to an IPU ground.

9.2 Outputs
All PWM (Pulse Width Modulated) and switched outputs are rated at a maximum of 2A. If a device will draw more than 2A, some type or relay must be used. If the output is PWM, do not use a “switching” relay, but rather a solid state type relay designed to be pulse width modulated.
There are four types of outputs that can be configured. The following lists them and reviews wiring recommendations. The designation on the Pin Map (Outputs) is given first, then a description.
1. “H” – Switched 12V or “High Side” output – will output system voltage level.
Wiring: Connect the pin to the device to be triggered. See NOTE 1 above.
2. “G” – Ground or “Low Side” output – will output a ground trigger.
Wiring: Connect the pin to the device to be triggered. See NOTE 1 above.
3. “P+” - 12V Pulse Width Modulated output – Outputs a high side pulse width modulated output to control items such as a progressive nitrous solenoid or a PWM IAC – will output system voltage level. See NOTE 1 above.
Wiring: Connect the pin to the device to be triggered. A PWM device has 2 wires, connector the other side of the device to ground.
4. “P-” – Ground Pulse Width Modulated output – Outputs a low side pulse width modulated output to control items such as a progressive nitrous solenoid or a PWM IAC. See NOTE 1 above.
Wiring: Connect the pin to the device to be triggered. A PWM device has 2 wires, connector the other side of the device to a voltage source.