Posibble to drive 8 injectors from the KA ECU? Highly technical!

[node]

This question is for the engineers and ultraknowladgeable ONLY!

Would it be posible to use some high power op amps, one for each injector to run an aditional injector? Almost like hooking up 4 aditional injectors in parallel with the stock ones but, without an extra electrical load on the ECU.

I was thinking that I could use a simple follower circut on each of the injector wires from the ECU. I could then run a set of secondary injectors anywhere I see fit.

The curcuts would each only be dealing with like 50Hz MAX @7000 rpm so some cheap radio shack parts should even work.

The idea of the system would be to avoid having to buy those expensive 550cc or larger injectors. The aluminum intake would be quite easy to machine out holes for another fuel rail.

[WDRacing]

I already have a system that lets you use 4 additional injectors, no splicing into the stock harness. The main problem with your design is there is no way to trigger the suninjectors set. They can't be on all the time, only under boost.

Keep working though, thats how I get things done all the time. Simple trial and error.

WD

[ca240]

hey i was kinda thinkin about somethin along these lines of the additional injectors as an alternative to larger ones...i've got my intake manifold all disassembled and stuff and there is a little screw lookin thing with a hex head on each one of the runners...could you make some adaptor to put in there and put the injectors into the adaptors or somethin?...it doesn't look like those screws are holdin in anything...if you dont know what i'm talkin about post a pic of a ka24e intake mani...the lower part..thanks

[fiznat]

what WD said, you cant just dump fuel all the time, you gotta have it in porportion to the boost. I suppose you might be able to rig up some sort of resistor dealey that worked off of a MAP sensor, but I think it would be overly complicated... not really worth it when you can get a specialized extra injector controller from SDS that references both RPM and the MAP sensor.

[bruinbear714]

You can easily tap off the injector wire and feed that into a power transistor to control an additional injector. Of course, you will need some sort of fuel controller to alter the MAF voltage so that the ecu will halve the duty cycle. In fact, you can drive as many additional injectors as you want, provided that the power transistors can handle the loads, and that the fuel pump can keep up.

I just think that's too much work to get additional fuel into the cylinders.... the method I have been working on is a AFC (pretty much like the SAFC) that intercepts the MAF, looks up a modifier value based on tps and rpm, and puts out a "corrected" value to the ecu. The table is going to be 16x16 or 32x32 if there are enough RAM on the microcontroller that I am using. The tables can be adjusted in real-time with a laptop through a serial port.

I have the pcb drawn out and layed out. I just have to get off my lazy *** and write the micro-controller code for it and the vb app to talk to the unit. :ylsuper

Once that gets perfected, I'm going to plop in either the Z32 or the Q45 MAF and either 370cc or a top feed rail + 72lb injectors and re-adjust the unit. That'll give a lot of headroom for gobs of boost later down the road.

[node]

The main idea with aditional injectors would be to add some small ones 200 to 300. That way the total max fuel volume per runner would be like 500cc(stock injectors +ghetto injectors). I could then trim down the extra fuel with a SAFC or emanage.

So cheap junkyard low flow injectors + home depot fuel rail + some sort of fuel management * ElcheapO T3 = Ghettofabulous horsepower!

bruinbear714 Sounds like you know whats up. So I could just use a simple current follower circut right? Or should I just get some high power transistors and set them to saturate above 4V?

Do you know if the ECU output is square wave or does it spike and then level out in some sort of peak hold type wave?

[WDRacing]

You could do the extra injectors with a hacked MAF for ultra cheap. Thats your best bet right there.

WD

[bruinbear714]

Not sure about what you mean by saturating above 4V, but if you use an n-mosfet with the injector connected to +V and the drain of the fet, have the source grounded, and have the gate connected to the primary injector wire through a small value resistor, you could control an additional injector. Even though you will be operating the fet as an on/off switch, it'll still heat up, so you will then have to worry about heatsinking the device, etc etc.

It's more trouble than it's worth. I've thought about this method a while back and figured there are much easier implementations of getting more fuel into the engine.

[node]

Yea I think is worth the money to buy bigger injectors and an FPR. I hadent considered all the extra time I would be spending getting the mess up and running correctly.

I think Im going to use 3rd gen RX7 FD 550s. Anybody running those? I think the 3rd gen uses side feed but the 2nd gen uses top feed.

[fiznat]

<-- 4 extra MSD 50#ers on a JWT fuel rail inside the intake runners, controlled by a SDS EIC. halfway there.

[IvoryJ30t]

This question is for the engineers and ultraknowladgeable ONLY!

Would it be posible to use some high power op amps, one for each injector to run an aditional injector? Almost like hooking up 4 aditional injectors in parallel with the stock ones but, without an extra electrical load on the ECU.

I was thinking that I could use a simple follower circut on each of the injector wires from the ECU. I could then run a set of secondary injectors anywhere I see fit.

The curcuts would each only be dealing with like 50Hz MAX @7000 rpm so some cheap radio shack parts should even work.

The idea of the system would be to avoid having to buy those expensive 550cc or larger injectors. The aluminum intake would be quite easy to machine out holes for another fuel rail.

no sense in using an operation amplifier in a digital circuit. use darlington transistors.

even then its still more trouble than its worth, because after you go through the trouble of making the transistor pack, you have the problem of spraying fuel into a manifold designed for air [uneven distribution]

[IvoryJ30t]

nevermind the part about the manifold, i missed the part about the seperate fuel rail and injectors. also the mosfet will have a better reaction time than darlington transistors, you dont want to skew the lag time of the injectors. if they are farther away from the ports, and opening slower than the base injectors, your ****ing up the flow.

but that should debunk it anyway. your going to drill the manifold, get an extra fuel rail, plumb both rails, drive the additional injectors, BUT YOU WONT BUY HI FLOW INJECTORS???

come on.

[node]

Hehe yea silly but, I am just trying to find the cheapest rout to go here. Im not trying to waste your time. Like I said, I think Ill be using 550cc injectors. I just thought it would be a cool idea to kick around.

I dont think lag time would be an issue no matter what is used to drive the extra injectors. We are only looking at like 50hz. (Max rpm)/(2 four cycle motor) = injector pulse per min

bruinbear714, So are you using a basic stamp type microcontroller to build your AFC? If so how are you planning on generating the signal to send to the ECU? Have you looked at the OOPic? I think it has built in D/A and A/D converters.

[bruinbear714]

Hehe yea silly but, I am just trying to find the cheapest rout to go here. Im not trying to waste your time. Like I said, I think Ill be using 550cc injectors. I just thought it would be a cool idea to kick around.

I dont think lag time would be an issue no matter what is used to drive the extra injectors. We are only looking at like 50hz. (Max rpm)/(2 four cycle motor) = injector pulse per min

bruinbear714, So are you using a basic stamp type microcontroller to build your AFC? If so how are you planning on generating the signal to send to the ECU? Have you looked at the OOPic? I think it has built in D/A and A/D converters.

Well I don't want to say too much without giving away the design, but I'm using a Zilog 8-bit microcontroller that has 12 10-bit a/d converters onboard, and an external 12-bit d/a, on a custom pcb that's around 3"x3". Programming for the microcontroller is done in ASM, while programming for the interface software is in VB, how fun. :oface If you want to talk, AIM to BRUINBEAR714.

[huguetpj]

...the method I have been working on is a AFC (pretty much like the SAFC) that intercepts the MAF, looks up a modifier value based on tps and rpm, and puts out a "corrected" value to the ecu. The table is going to be 16x16 or 32x32 if there are enough RAM on the microcontroller that I am using. The tables can be adjusted in real-time with a laptop through a serial port.

I have the pcb drawn out and layed out. I just have to get off my lazy *** and write the micro-controller code for it and the vb app to talk to the unit. :ylsuper

Once that gets perfected, I'm going to plop in either the Z32 or the Q45 MAF and either 370cc or a top feed rail + 72lb injectors and re-adjust the unit. That'll give a lot of headroom for gobs of boost later down the road.

I thought about that possibility a while back, but once you get the fuel going what about spark? That's why I'm still betting on hacking the ECU... by the way bruin, any news on that front?

[bruinbear714]

I thought about that possibility a while back, but once you get the fuel going what about spark? That's why I'm still betting on hacking the ECU... by the way bruin, any news on that front?

Spark can also be handled by the mcu doing the adjustment... you would need to tap into the ignition wire from the ecu and feed that into a delay circuit that can be controlled digitally by the mcu.

As for re-programming the ecus, I've reprogrmamed the KA24E ecu to adjust the rev limiter and that worked. I left it at 5000 and the car wouldn't rev past it.

For the KA24DE, I havn't had time or the resources to look into that since I've decided to just fork out the cash and go the emanage route.

[huguetpj]

Spark can also be handled by the mcu doing the adjustment... you would need to tap into the ignition wire from the ecu and feed that into a delay circuit that can be controlled digitally by the mcu.

But then it gets complicated...

Quote »As for re-programming the ecus, I've reprogrmamed the KA24E ecu to adjust the rev limiter and that worked. I left it at 5000 and the car wouldn't rev past it. .[/quote]And so I've heard, but the E is easy... jeje

Quote »

For the KA24DE, I havn't had time or the resources to look into that since I've decided to just fork out the cash and go the emanage route. [/quote]Me neither. I need to get myself a universal programmer to read the versatile ROM thingy but I've had no job for months and money is scarce.

I'm too pondering the emanage route.

[bruinbear714]

But then it gets complicated...

Not really... I already wrote the program on a zilog microcontroller to adjust the maf voltage every x milliseconds. I suppose I could add an extra output to the delay circuit to control the delay everytime the zilog updates a new voltage.

[huguetpj]

Not really... I already wrote the program on a zilog microcontroller to adjust the maf voltage every x milliseconds.

That's the easy part

Quote » I suppose I could add an extra output to the delay circuit to control the delay everytime the zilog updates a new voltage. [/quote]I haven't really taken a look at the spark circuit, but I'm guessing (simplisticly speaking) that the ECU controls a relay for each plug? Or are the relays internal to the ECU? If they are external and the uC can work delays then I'm guessing it ain't that hard, just need a MAP sensor and your almost set. Hmmm...maybe I could use the Motorola uC I have lyign around.... :pface

Anyway I think we are way of topic here, maybe you wanna drop me an email to further discuss this.

[node]

[quote=" bruinbear714

Spark can also be handled by the mcu doing the adjustment... you would need to tap into the ignition wire from the ecu and feed that into a delay circuit that can be controlled digitally by the mcu.[/quote]

That wouldn't be to hard to do. You could use an el cheapo OOpic or similar microcontroller and a map sensor. The whole process could be handled by a simble equation like (MAP voltage*Constant) = Delay for output to igniter. That would retard timing X ammount per PSI. I will try this when I finally go high boost.

[Jonny 290]

Install another 4 injectors, plumb into fuel rail.

Build 4 drive circuits that switch on and off with the original injectors. You've got drive signals at the ECU, which is where I'd recommend pulling the circuit off of.

Injectors run with pulsewidth modulation, so there are no analog values to worry about from the injectors to the ECU. On and off.

If the new injectors are running at the same duty cycle as the originals, at any given time, your fuel correction is simple. Adjust for an EFFECTIVE injector size equal to the sum of the old and new injectors. Example: 270cc KA injectors + 370cc SR injectors = 640cc/min of injection.

Do the math, set your SAFC, and you should be good to go.

[node]

Exactly what I was origanally thinking. Couldent have said it better myself.

[bruinbear714]

That's the easy part



I haven't really taken a look at the spark circuit, but I'm guessing (simplisticly speaking) that the ECU controls a relay for each plug? Or are the relays internal to the ECU? If they are external and the uC can work delays then I'm guessing it ain't that hard, just need a MAP sensor and your almost set. Hmmm...maybe I could use the Motorola uC I have lyign around.... :pface

Anyway I think we are way of topic here, maybe you wanna drop me an email to further discuss this.

I just posted my thoughts on how to design a piggyback system that can do air flow adjustments, duty cycle adjustments, and retard timing. Its on the secret area on my website.

[huguetpj]

I just posted my thoughts on how to design a piggyback system that can do air flow adjustments, duty cycle adjustments, and retard timing. Its on the secret area on my website.

Then maybe you wanna drop me an email with the secret location on your site.... :pface