Megasquirt - a story of injection

[Shaunp]

Shaun, Where were you planning to fit your filter and pump?


SA laws don't allow any fuel lines or pumps inside the boot unless it's engineered and completely blocked off from passenger compartment (inc gases). That leaves me with very little room for a surge tank (tucked up behind diff perhaps?).

The sump like you're doing would probably work best for me. Was thinking my filter & pump could be tucked up between tank and rear valance with a check valve to stop it draining back. Only concern I have is in a rear end collision it would get crunched.

I'm going to mount it under the floor somewhere maybe where Boof had his or Ill make a bracket and mount it in-front of the tank in the axle tunnel. I figure I'll weld some tabs around the tank to tie the lines to.

[ozbilt]

Shaun, Where were you planning to fit your filter and pump?


SA laws don't allow any fuel lines or pumps inside the boot unless it's engineered and completely blocked off from passenger compartment (inc gases). That leaves me with very little room for a surge tank (tucked up behind diff perhaps?).

The sump like you're doing would probably work best for me. Was thinking my filter & pump could be tucked up between tank and rear valance with a check valve to stop it draining back. Only concern I have is in a rear end collision it would get crunched.

I'm going to mount it under the floor somewhere maybe where Boof had his or Ill make a bracket and mount it in-front of the tank in the axle tunnel. I figure I'll weld some tabs around the tank to tie the lines to.

Bolt the tank in place using riv-nuts. Use bolts that are longer where you need them to clamp lines in place & use P clamps.

[Shaunp]

Shaun, Where were you planning to fit your filter and pump?


SA laws don't allow any fuel lines or pumps inside the boot unless it's engineered and completely blocked off from passenger compartment (inc gases). That leaves me with very little room for a surge tank (tucked up behind diff perhaps?).

The sump like you're doing would probably work best for me. Was thinking my filter & pump could be tucked up between tank and rear valance with a check valve to stop it draining back. Only concern I have is in a rear end collision it would get crunched.

I'm going to mount it under the floor somewhere maybe where Boof had his or Ill make a bracket and mount it in-front of the tank in the axle tunnel. I figure I'll weld some tabs around the tank to tie the lines to.

Bolt the tank in place using riv-nuts. Use bolts that are longer where you need them to clamp lines in place & use P clamps.

good plan

[Dwayne]

Is upgrading from a 1 to a 2 etc just adding a daughterboard?

[boofhead]

an MS1 to MS2 is a daughter board plus power circuit changes
a MS2 to MS3 is a daughter board plus case changes

[Husky65]

So I was thinking about how I'm going to wire the MS in, and came up with a rough schematic. I'd like you fellas to go over it and let me know how crap I am at it ?

I would like to use a bussmann relay/fuse box as I already have a new one sitting on my shelf. This has two common terminals. One is for +12 that powers all the fuses and then can be connected to the relays. And the other is meant to be for a common ground for the relay ground pins. As I don't want all the relays to be on the same ground(due to using the MS to switch ground on for the fuel pump fuse), I would like to use the ground terminal as an ignition +ve terminal, as all the relays are switched by ignition. I will then use ground as the 'signal' wire to the relays.

I have a power cable that goes from the battery in the boot to the starter terminal, and as this cable goes right past where I want to put the fusebox, I would like to tap into this battery cable with a splitter to supply power to the fusebox.

Below is a schematic and some pictures of the bussmann relay/fuse box. Please, any advice/opinions...don't hold back

[Dwayne]

Looks good to me, but might be worth getting a 2nd opinion if you don't want the car to catch fire immediately.

[hybrid]

You'd need to double check the capability of the fuel pump transistor.
I'm not sure it has the capacity to drive 4 relays. You could upgrade it if you really wanted to go that way.

What I do is power the positive side of the relays for injectors, coils, fans etc from the fuel pump relay output.
So the FP output on the MS only activates one relay. And that relay does the rest.

I do like that box concept though.

[Husky65]

Yup got ya. Do the coil and sensor relays need to be connected to the ecu. If not I can run all the relays to chassis ground except for the fuel pump relay

[hybrid]

- Yes, O2 can be powered from that separate relay. If it has separate GNDs for heater and sensor, the sensor GND should go to MS sensor GND and heater GND to the engine with the other main MS GNDs
- MAF - not sure, haven't used one (are you using this with blower?)
- IAC - yes it can be powered from that separate relay
- Crank depends on the type of sensor. VR doesn't need any power - it generates its own voltage. Hall Effect will need external power, but depends on the sensor. Mine is powered by 5V VREF and GND is connected to sensor GND.

[Husky65]

Not sure if I'm going to use maf but will run a wire anyway just in case. That sensor relay is there basically to power any sensor that needs 12v ignition power. Not sure on what vr sensor I'll be using yet.

So a revised schematic would be like this.

[hybrid]

Yes and you could draw a link from Pin87 on the fuel pump relay to pin 85 on the bottom 3 relays if that box setup can do that. Looks like a common power rail though.
You don't really need/want to have any of those powered (except maybe MAF) while the fuel pump is off.

The fuel pump transistor is a 2N2222A.
Looks like it can handle 800mA continuous.

You could measure the coils of those relays, as long as they were drawing <200mA each, you could drive all 4.

You could switch the transistor to something like a BC639 which will handle 1A, so would easily handle all 4.

[Husky65]

Yeah pin 85 is a common rail, you don't have access to it underneath the fuse box, so I can't use the power from the fp relay to switch the other relays.

Silly me forgot the fan relay will be grounded by the fan control output of the MS. So the fuel pump ground will have to ground 3 relays if I run it that way.

So these are the latest 2 schematics options:

[lukep6470]

I am using an EECIV harness with a Microsquirt adapter cable. It only has 2 relays. One for the Fuel Pump and one for everything else. I just have one 20amp (I think, might be 30) going to the main power feed for the harness.

This setup has run fine for a daily driver for the last 5 years. The Megasquirt solution does help with troubleshooting though.

[lukep6470]

I am using an EECIV harness with a Microsquirt adapter cable. It only has 2 relays. One for the Fuel Pump and one for everything else. I just have one 20amp (I think, might be 30) going to the main power feed for the harness.

This setup has run fine for a daily driver for the last 5 years. The Megasquirt solution does help with troubleshooting though.

Say that the thermo fan is a completely different non-ecu circuit.