Looking for some help with sequential fuel injection for a 1.6 engine.
I just picked up an Electromotive Gt and plan to run it on my FP miata.
I need to provided a camshaft angle signal to the ems for sequential fuel injection. I am looking at modifying a cas to do the job. My first question, is there one cas that is preferable to modify? I have not seen the inside of a 94-97 cas. For signal I thought about having a plate machined to provide the rising edge to trigger the signal, and making the appropriate modifications to the housing of the cas to hold the sensor. Does this sound like a viable solution? This stuff is a bit over my head, but will be worth the trouble and headache as it will allow my tuner to trim the injectors and even up cylinder temps.
One of the other reasons I have chosen to go with the electromotive is the ability to use a potentiometer to control mixture on the fly. If the car is running a bit rich or lean of target AFR adjustment is as simple as moving a slider one direction or the other. I lost a qual session at RA due to a miss calculation on fuel, the electromotive once properly configured, will prevent this from happening.
Any ideas, pics, or dyi instructions on modifying a cas to provide the needed signal are greatly appreciated.
Last edited by hingstonwm; 10-11-2012 at 05:56 PM.
I'm honestly not sure it's possible anymore to make a distinction (by year) as to which engines are going to have the optical style sensor (with a slotted flat plate) as opposed to the magnetic sensor (with two concentric cups with teeth stamped into them.)
If you can find a magnetic-style sensor, you can easily cut one of the two teeth off of the CMP cup and not have to machine any fancy new parts.
You can see that the larger, outer cup has four evenly-spaced teeth. That's the "Crank" signal.
Barely visible beneath it is another cup with two teeth. That's the "Cam" signal, and if you slice of one of those teeth, you'll have an absolute phase reference.
None of this should be necessary.
Regardless of whether they had an optical or a magnetic CAS, the '90-'97 engines all produced exactly the same CAS pattern.
One of the two CMP teeth is longer than the other, such that it's high during an entire rise-fall cycle of CKP, whereas the other CMP tooth is high during a CKP rise, but low during a CKP fall:
This is enough information for most ECUs to figure out the difference and run fully sequential. The stock '94-'97 ECUs worked this way, as do the MS2/3, the Hydra, etc. I don't know anything about Electromotive, but it's worth investigating whether it can run sequential withou havig to modify your CAS. When speaking to the Electromotive crowd, you may find that they refer to our CAS pattern as "4G63", as that was the Mitsubishi engine which it was originally installed on.
Electromotive at least up to the Tec3 needed a single pulse somewhere from 90 to 3 degrees before TDC.
If I remember correctly, I had to modify the NA CAS quite a bit to get that to occur. I used the inner wheel and removed one of the teeth maybe. Then I drilled a hole for the tiny little locating pin on the center shaft rotor thing to reposition it so it would fall in that 90-3 degree range. You only have to get it close because you do get some adjustability on the CAS for timing.
The four-tab wheel is keyed to the shaft which is keyed to the cam. The inner/bottom/smaller wheel is keyed via a pin to the top/outer/bigger wheel. Drilled the new hole in the top wheel to relocate the bottom one. Smaller wheel has the second tab removed.
It works with either setup. Just put some opaque tape over the holes in the optical CAS and/or drill new holes where you need them. HVAC aluminum tape is cheap and easy and you probably want some anyway.
I would recommend against tape on something that spins at double crank speed in a race car, but maybe I'm paranoid :-)
Half crank speed.
The aluminum tape might work. Honestly, I've never really checked to see how much clearance there is between the sensor and the plate. If it's wide enough for a piece of tape to fit comfortably, then by all means have a go at it.
I will send a pm to Hustler, to see if he is interested in selling. I am running a 60-2 crank wheel, so I only need the cmp signal. I will need to index the cas and see if I can just rotate it and trigger the signal within electromotive's parameters. If not then I will need to index, unless Hustler is willing to sell his.
Quick update, I picked up a cas off eBay for 90 bucks. Luck was on my side as it is the magnetic pickup type. I will have to go through my wiring harnesses, but I'm sure I have one that has the cas connector. I am running electromotives 60-2 trigger wheel, so I won't need the cmk signal. The cas that is currently on my engine is gutted, the new one will be modified and take its place, so I can setup sequential fuel injection. I am hoping that sequential fuel injection will also give me a more accurateafr readout on my uego.
Update. after reading the manual I need a signal between 180 and 6 degrees btdc. It looks like I can acheive this without modifying the timing in the cas. I took a few pics, not sure if the pulse is triggered as the tooth enters the magnetic field or after it passes.
the goal of the pics is to shoe relative position of the tooth on the cas as compared to crank angle. let me know what you think. The crank position wheel was removed so I could see the timing on the cam wheel.