8 replies to this topic

[cooperpooper]

Hey Everyone!
About a year ago I made my first post here asking how to go about setting up my stock 1999 Japan Spi mini on a speeduino ecu. Well a couple months ago I decided to pull the trigger and try it. I have since extended the factory engine harness into the car and adapted it to plug into my speeduino ecu, as well as added a 14point7 brand wideband sensor for tuning purposes.

I have gotten the easy sensors such as tps, map, and temp sensors calibrated and working. and have also learnt I need to replace my ignition coil with a smart coil to work with the speeduino. I believe some people have used the ngk u2003 coil from a vw golf, but are there other smart coils that would also work?

The main point I am currently stuck on is the wiring and set up for the single injector. So far I have measured the resistance of the bosch 0280 150 682 injector to be 1.3 ohms so i will be adding a 8ohm resistor in series with the signal wire from the ecu as the speeduino only works with high impedance injectors.

Going off this wiring diagram (https://www.manualsl...?page=19#manual) there are only two wires that go from the original mems ecu to the injector. Based off this manual on page 13(http://britishminico...r/RoverMEMS.pdf), those wires connect to pins 1 and 24 which are for injector pulse 4 and injector pulse 1 respectively.
I’m pretty confused here, visually i have seen that the wire to pin 1 (injector 4 pin) connects to the negative terminal of the injector and the wire from pin 24(injector 1 pin) to the positive terminal of the injector. But how would I adapt this to work with the speeduino? My idea was to have one signal wire for cylinder 1&4 and another for cylinder 2&3 from the speeduino to the single injector. Am I kind of on the right track here or completely missing the mark?

Sorry for the long post but just thought I would add every piece of information i have so far.
Thanks! Felix

[Avtovaz]

what coil is on it now? you dont need to replace it. it it ran the dizzy, then you can run that, as a guess you could use a bosch 222067034 . if it had a non driven coil pack you need a bosch 0227100200 ignition amp. These units turn the signal from teh ecu to the coil from a 5v signal to a 12v signal.

 

go down to number of injectors, change it to 1, and itll fire the first injector output to run the single injector. Itll pulse it 4 times per engine cycle  

 

dont forget to wire in the heater plate on the bottom of the inlet, from what i gather, the fuel is sprayed onto it, it atomises and the spray then gets sucked to where it needs to be minimising charge robbing issues. they even used this on late carb engines on cars like fords. 

 

Use rover Mems on the set up type and hopefully itll decode your Mini flywheel trigger pattern automatically. if not pm me and i know the guy who coded my set up in but id need a pic of your flywheel.

 

this time next year hopefully ill be doing the same as i have a Lada 2103 im going to be running on a Lada SPI unit. 

Edited by Avtovaz, 01 March 2025 - 11:04 AM.

[cooperpooper]

Thanks for the reply! right now the factory mpi coil is on the car. You’re right i could just add an ignition amp but the smart coil i mentioned is not much more expensive then the amp itself so I just thought I would replace the 25 year old coil with it and save the amp step.

So If I just wire the injector into one signal output it will be able to fire enough times per cycle? I don’t have to trick the ecu into thinking there’s more than just the one injector? I’ll definitely give that a try.
I am still confused where the injector gets its power from? or is the signal wire acting as power and then the other wire going to pin 1 on the original ecu is the ground?

To wire in the heater plate, My plan was just to use one of the programmable low current outputs on speeduino and connect the wire going to the heater relay, then just program the output to turn on when coolant temp is below 75 c and off when above that temp. I believe that is how it was configured from the factory. But could I possibly do away with it completely and just use proper fuel enrichment settings when the engine is cold, or would this not have the same effect?

I have used the rover decoder and i think it has successfully worked as i get a rpm signal of ~250 when cranking. My only concern is I’ve read that the mpi (or some i really don’t know) had a trigger wheel with a 17-17 pattern and spaced 180 degrees apart, therefore the ecu wouldn’t be able to tell where tdc is. But i don’t really have a way to get a look at the flywheel to confirm this or not.

[sonscar]

Are you using wasted spark?Tdc firing stroke is less important if so.The injector is usually 12v live switched on one pin and the ECU earth's the other pin.I am not mini specific but injection is usually of this format.Steve..

[cooperpooper]

Yes wasted spark is my plan so thank you that calms me down, not to mention it was wasted spark from the factory with just the crank signal so i’m pretty confident it will be okay.

That is how I thought they are normally wired as well, but the two wires from the injector go into the mems ecu.
I could try to wire the injector into the speeduino using a 12v switched and ground through ecu. I’m just worried i’m going to wreck the injector by having improper wiring as i know they are near impossible to find anywhere anymore.

[Avtovaz]

oh right ok so the injector witht eh standard ecu probably got it power, you need to give it 12v and the ecu will ground it.

[cooperpooper]

Ok great thanks! 

I'll try with giving it power from the same switched 12v that is powering the wideband sensor, and then just grounding it to the injector 1 pin on the speeduino. If I find I need to trick the ecu into thinking  there are multiple injectors I can always add another ground/signal to the injector 2 pin

 

I'm guessing the 8ohm resistor will have to be added in series with the ground/signal wire going into the speeduino, as this is what the speeduino manual states: "If "Low-Z" ("peak and hold" or PWM-controlled) injectors that are lower impedance are used, the wiring will require series resistors on each injector to avoid damaging the board with excessive current."

 

Does anyone have any info on what the injector duty limit or open time should be for a setup like this? 

[Avtovaz]

yes think you are right on the wiring of the injector. The duty cycle, when you goto speedyloader pick a car tune file, then just stick with the major things, i dont think from what i remember duty cycle is much different on most type of injector. I think my R100 was running 90%, but i think that is max.

 

what type of speeduino do you have and where did you get it?

 

i had ua4c.

[cooperpooper]

So I just measured the voltage that is going through the injector cricuit currently when cranking with the mems ecu plugged in and its only between 0.5v-1v, which doesnt really make any sense at all right? maybe im measuring wrong? It should be 12v, or at least it will be if i wire it like above, and I really dont want to fry this injector.

 

I have a ua4c speeduino from wtmtronics.