Jump to content

Finding the right ECU


Recommended Posts

Hey guys, 

I am currently running a megasquirt MS3Pro and while I really love its user friendly interface and tons of in/out options I am truly tired of its failures from poor quality control. It has failed 3 times now from mfg defects and as frustrating as wiring in a whole new setup is...I believe its time. 

Looking at the "which ecu is for me" page on the main website it looks like the G4+ Extreme is what would most closely match what I have currently but I wanted to ask to be sure. 

My setup is this:

Small Block Ford v8. Approx 1000 hp but semi-daily street driven

Single Turbo - e85 - non-intercooled

Full sequential fuel and spark with 8 individual coils - 2200 cc high imp injectors

36-1 crank wheel (hall sensor) with single tooth cam syncronizer (vr sensor)

Sensors used CLT, IAT, MAP, TPS, Knock, Exhaust backpressure, Fuel Pressure

4 port mac boost solenoid controlled by the ecu - pwm duty cycle based on RPM vs Map (1 pwm output)

Electric fan (1 std output)

Staged fuel pumps. 1 constant, 1 active at 110kpa (2 std outputs)

Meth injection ECU controlled - duty cycle based on RPM vs Map and uses 2 outputs. One for pump on/off, one to pwm a fast valve. (1 std and 1 pwm out)

Transbrake/2 step ecu controlled (1 std output but later may need pwm for a bump box)


Another issue I have with my current ecu is IAT heat soak during short period shutdowns. The only fix in this old setup is to increase afterstart enrichment for a long period of time for 140+ clt temps. My setup is non-intercooled and the intake charge pipe runs between the motor and radiator. While IAT's are reasonable during driving, it soaks to 180-200F during 2-5 min shutdowns - like stopping at a gas station and makes restarts painful. Tuner studio has limited ability to adjust for this so I am wondering about the Link abilities as well. 

I have looked at other ECU's and the EMU Black almost fits the bill but limited outputs and having to use Aux outs for the 7th and 8th injectors plus the need for wasted spark make me consider elsewhere. 

I really just want to make sure I am not missing something with the g4+ extreme capabilities. 

What dedicated outputs does the extreme have not counted in the 10 aux outs? Are there dedicated outs for Fuel pump and Fan?

Sorry for the short story. Any advice is greatly appreciated. 

Link to comment
Share on other sites

Its a shame about the amount of people who fall in the MS3 trap, it seems good valve but isn't really a good product for anything other than a hobbyist, I have replaced about 5 in the last year because of various issues.

I counted that you need 7 outputs (on my fingers) so excuse me if I missed one.

The Xtreme has 8 ignition and 8 Injection outputs as well as 10 Aux Outputs, none of the outputs are preconfigured but they do have some constraints.

Your best bet is to familiarise yourself with the software, the help file has all the wiring diagrams and information about the outputs you need.

You can download the software here:


I have attached a picture of the config from the sample map.


Screen Shot 2018-02-18 at 19.48.25.png

Link to comment
Share on other sites

Thanks Clint. 

I have downloaded the software since making the post and have played a little. 

I didn't mention that I also have a stepper IAC valve and I am not seeing any direct control in the software but I may be missing it. The EMU black needed to bridge 2 outs to drive an IAC coil so I am not sure about the Link. 

Link to comment
Share on other sites

Is the Stepper IAC a 3, 4 or 6 wire ?

3 Wire IAC Valves use 2 Aux Outputs

4&5 Wire IAC Valves use 4 Aux Outputs.

If you run out of outputs then the only 3 options for you are:

  • If you have cams that give smooth idle and not too much electrical load then you can delete the IAC and you can use Idle Ignition Control, which works very well.
  • Convert to a 2 wire IAC ( Ford EECIV Type)
  • Or go for the Thunder.
Link to comment
Share on other sites

Unfortunately it's a 4 wire, 2 coil stepper. 

That was one of the big draws for me on the MS3Pro. Dedicated outputs for tach, fan, iac, etc then had tons of high current and pwm outputs still available. 

Of course there are 2 things I can modify. 

Transbrake control isn't a must. I can just activate it with a button and have that button also act as an input to the ecu for 2 step activation. 

Then I can use only one output for the meth fast valve and just put the pump on a switch which also activates the meth control. That frees up 2 outputs and gives the extreme enough to work my stepper valve. 

Link to comment
Share on other sites

Join the conversation

You can post now and register later. If you have an account, sign in now to post with your account.

Reply to this topic...

×   Pasted as rich text.   Paste as plain text instead

  Only 75 emoji are allowed.

×   Your link has been automatically embedded.   Display as a link instead

×   Your previous content has been restored.   Clear editor

×   You cannot paste images directly. Upload or insert images from URL.

  • Create New...