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EFI Wiring Fundamentals

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Discussion and questions related to the course Motorsport Wiring Fundamentals

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Zac, while you are talking rx7 loom bits I might pick your brain and ask about the wiring course progress/content. I am trying to stick with the apexi ecu i have in my s8 and just add a few bits and pieces to allow high power with ancillary component operation on single turbo water injection. I have a billet coil kit with r35 COP but the sub harness is set up for 3 channel. I want to make a new sub loom and drop back to just the trailing channels so I can run more dwell (leading and trailing on each rotor on the same channel). I have already bought an ecu loom extension so that I can wire in my plex combustion logger without chopping things up. I will need to buy new connectors/pins/wiring for the ignition sub loom and buy a deutsch/round pin crimper for additional wiring of water injection level sensors/control and the plex "mil spec" round connectors. (I already have the crimp/pin tool set that Haltech sell for blade type connectors, and the plastic pin install remove for the round pins on the plex logger).

G'day Michael. The wiring content is progressing, not as fast as we'd like though, same story, everything takes longer than you expect. The first course, which is the reformat of the wiring fundamentals will be out early next month, fingers crossed.

We had a bit of a talk about your setup, and we've decided that you can keep your Apexi ECU. Just not in your car. On a shelf would be fine though ;-). I think with your performance goals, you would be better suited moving to a more capable and modern aftermarket ECU. Even a relatively cheap entry level ECU, like the Link Monsoon will let you achieve better results, easier, then sticking with the Power FC. I can say this because I have a Power FC in my FD, but its level of tune is far, far below what you're shooting for.

You need to be very careful if you want to fire your leading and trailing plugs on each rotor at the same time. Its a thing that people do, but it has the effect of increasing the ignition timing over all, so you can think you're running a relatively conservative ignition map, but in reality things are a bit closer to the edge than you realise.

Is there a reason you want to run more dwell? I wouldn't have though the dwell requirements of the R35 coils would be hugely different to the original coils, and if you're not getting any ignition misfires, increasing the dwell wont help you out at all, it'll just heat up the coils more and possibly cause them to fail faster.

I'm super jealous of your Plex Combustion logger! They look like an awesome bit of kit and I'd love to have a play with one, one day. Are you going to be doing any combustion pressure logging? If so, what are you going to use for a pressure transducer? Cool stuff. You will need a Daniels Manufacturing AFM8 tool to crimp the Soriau/Autosport pins correctly, with the right positioner head. The positioner head you need will be in the manufactures documentation for the connectors.

I'm happy to sign up for the electrical content first if you prefer but if you have plug part listing for the ignition and the solenoid control and/or pin outs in English as only the earlier stuff seems to be common. My intention is to run an optical level switch to drive a positive side relay to intercept power to boost/turbo control solenoids pwm/switched earthed by the factory loom and a hobbs switch to trigger pre-turbo water injection with the level switch dropping wastegate control if low and the factory loom secondary control switching triggering a smaller secondary water injector.

If you have a browse through this: Original Build Thread, i have plug listings in there somewhere that should have the info you're after.

I'm not sure what you're trying to achieve can you explain what you're doing a little more? I've read it a couple of times, but still cant figure it out... It is the end of the day though... ;-). First thing I'd note though it you need to be careful with the specs on and optical switch being used in a PWM application, as their internal switching times can be pretty slow.

Also, hit up this webinar from the archives: Rotary Ignition Tuning, should have some relevant info.

Hi Zac, thanks for your detailed replies. I'm very much aware of the spilt timing stuff. My intention was to slowly wind in the split while still using the 3 channel sub loom with all the combustion logger stuff hooked up, adjusting total advance to suit. I have 2 R7240.11 plugs which have been modified to accept Optrand sensors. I haven't found a lot on the r35 coils but saw comments on the guild page from guys reflashing gtrs that factory at load they were in the 3.8ms range. The apexi is 2.5 out of the box and if i extend port and want some overrev even 3ms is pushing DC really hard. I suspect I will need the dwell to fire through the WI. I have followed a lot of build threads and those that have been successful and consistent, especially without good pwm control to more carefully match water flow have all had CDI or IGN01A coils running decent dwell, including Green Bros. I know the R35 coils are well regarded but there is only so much energy a physically small coil can extract from a 13V supply in 2.5ms and in waste spark you are looking at 1/4 the available time relative to a sequential piston motor. After seeing a modern SAE paper (happy to forward) with chamber flow dynamics I'm very confident that for high loads at least I won't lose anything power wise with zero split and correct timing.

WI will be pre-turbo boost presurised tank with spray systems air atomizer. As used by a bunch of guys in the US, Omar at Raceonly in Sydney and Green Brothers on their drag sled. If I do move to a better ecu I will go to a single higher flow nozzle and 3d PWM map.

Optical level sensor is just a fail safe for water injection, I would use it to trigger a relay that intercepted positive power to the boost control solenoid, low water, i only get spring pressure.

Positive side hobbs switch to power primary and secondary atomiser solenoids, the secondary earth going to a secondary turbo switch wire in the standard loom so i can control switching rpm, assuming there is at least one with the correct logic sense.

My intention is to run a 4 channel thermocouple controller to allow rotor trimming and compressor inlet and outlet temps. As well as wideband in the dump, 2 channel plex knock monitor and grab what channels i can from ecu plug spacer beyond crank signals, and Map sensor that the available inputs on the combustion logger allow.

I have an engineering background and some reasonable resources available to me but no significant experience of quality auto electrical work. I do have the ability to borrow very good pressure transducers and DMMs for setup and testing. I intend to buy a 4 channel scope for myself. Not sure if I get a light bench unit or something like a pico?

I will be in NZ for 2-5 weeks at some stage in the next few months for measurement collaboration work, depending if i take recreational leave as well. I may have to opportunity to bring the logger, If I took a few days before and after official work it would mean I could leave the logger with you guys for a couple of weeks.