[tristessa]

Hey all. Looking at using Speeduino to get this car running more reliably. It's currently fueled with a single side-draft Zenith/Stromberg 175CD2 with a points distributor, the engine is a 2.3L inline 4-cylinder with two siamesed intake ports and never came with fuel injection. I'm using this thread as an inspiration, but looking to use an NO2C Speeduino for controlling the TBI unit because I don't need the complexity and features of MS for this. Planning to run it as fuel only at least at first....and maybe for all time, I mostly just want to get rid of that #%$#$ing carburetor because I'm tired of having to screw with it every time the weather changes slightly.

I've already collected a Mega2560, the TBI unit and an NO2C that I just finished assembling and loading the firmware last night. I have the fuel pump, VR conditioner, IAT and CLT sensors on the way, going to carve the adapter out of some aluminum this evening.

Is there anything else I'll need at first?

And is setting up the configuration of the base tune in TunerStudio really that easy?

Thanks!

[jonbill]

some find it easy, some less so. you'll need a crank position signal and throttle position sensor too, and probably connect the MAP sensor to the throttle body. what is the 'TBI unit' you referred to?

[tristessa]

Single-barrel TBI from a late '80s Chevy Cavalier 2.5L. Has a single injector, a TPS and an IAC valve built into it, along with a nipple for a MAP sensor, and will be feeding all four cylinders through the intake manifold. Looks like this only mine isn't this clean yet:

Kinda hard to do port injection when there's only two intake ports feeding four cylinders, hence looking at doing a throttle-body injection.

If I'm using the "basic distributor" option and using the Speeduino for fuel only, do I actually need a crank signal? I didn't get the impression that was needed for a use like I'm planning.

[jonbill]

yep, basic distributor works.
Sounds like you've got all the bits you need.

[tristessa]

Cool. I'm 3D printing a case for the ECU and going to print an adapter for the stock air cleaner duct that has a place for the IAT sensor, but the model for that can't be finished until the TB is mounted in place. I figure it'll be a good use for the spool of NylonX filament(carbon fiber reinforced nylon) I've got sitting on the shelf, but the ECU case is just ABS because it's much cooler under the dash.

[PSIG]

Unless you can do deep-port injectors injecting on the valve (so the other cylinder doesn't steal the fuel), the common option is to feed lots of squirts as a constant flow of fuel so each cylinder gets its share. Playing with the injection timing (end-point) should help find that sweet spot at various speeds for even fuel distribution. Good luck!

[tristessa]

Finally getting back on this after a soggy winter/spring and the emergency home repairs that came from it.

TBI is mounted, CLT is intalled, fuel pump mounted & hoses run, O2 sensor installed in the exhaust pipe just past the cast iron manifold. I've 3D printed an adapter to sit between the TBI and the factory air cleaner assembly, which also serves as a mount for the IAT sensor. I'm 90% done with the wiring harness, but I'm a little stumped on connecting to the points-and-condenser ignition system for "basic distributor" mode, and what I need to isolate & protect my Speeduino from whatever stray voltage spikes might come from the ignition.

From the NO2C I have VR1+/VR1- wires, and on the ignition coil I've got + and -, with the - terminal going to the distributor. Is it just coil - to VR1- with an optoisolator in between for protection?

Thanks!

[PSIG]

If you are controlling ignition with a points distributor, the points wire is disconnected from the coil and moved to VR1+ (with 5V pullup jumper ON), creating a 5V-0V signal. The coil(+) is connected to +12V as-usual, and the coil(-) will be connected to an ignition driver (coil module or 'igniter') or 'smart' coil connected to IGN1 signal output.

If running fuel-only with stand-alone ignition; most commonly the coil(-) signal is fed to VR1+ through a signal conditioner. A conditioner that can handle up to 450V coil flyback voltage and condition to 5V-0V is required. That is most common, but there are other signal source options.

The Toyota PRW-2 ignition coil driver is one of many common and inexpensive coil driver modules to choose from:

PRW-2_ignition_module_sm.png (50.7 KiB) Viewed 4080 times

[tristessa]

Cool, thanks for that. Years ago I used a points distributor to trigger a Ford TFI module and coil, and I think I've still got the module around in a box somewhere if it would be useable for this, otherwise I'll order in the Nissan module.

If I were to connect the points to VR1+, the IGN output to the coil and zero out the timing maps in TStudio, would that leave the spark timing entirely up to the centrifugal & vacuum advance in the distributor? I'd*like* to leave the ignition system alone as much as possible and just use Speeduino for fuel. Trying to keep it as original-looking as possible under the hood, so coil packs or coil-on-plug is a no-go.

[PSIG]

Cool, thanks for that. Years ago I used a points distributor to trigger a Ford TFI module and coil, and I think I've still got the module around in a box somewhere if it would be useable for this, otherwise I'll order in the Nissan module.

The TFI or a zillion other modules can work for a coil driver, so go for it if that suits you. Note all drivers will need a heat sinking mount, and that may be simpler with certain modules. One of my favorites for this work is the DSM/Subaru/Ford J121 module. Small and very robust. Connectors are easy to find (standard Bosch/TE/AMP Jr Power Timer) or just solder to the pins. Using the TFI module as a coil driver, the wiring is TFI pin:

1. Block GND
2. Coil(-)
3. Switched 12V
4. NC
5. Speeduino IGN1 @ 12V
6. Switched 12V

If I were to connect the points to VR1+, the IGN output to the coil and zero out the timing maps in TStudio, would that leave the spark timing entirely up to the centrifugal & vacuum advance in the distributor?

Yes, you could, and there's a thread about this. Set-up like that (including coil driver), the only difference is locking the advance and adding stock timing values to your table, also described in another thread. Appearance would be identical, and would be my next step.