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I am converting an older Motoronic system to modern control system. I am trying to make all the parts in a way that will work with a handful of control systems so I can help many owners with whatever system they prefer.
I am going COP, so the distributor and ignition rotors are being removed. I need to make a blanking plate for the distributor caps, so thought it would be a good opportunity to include a more modern hall sensor and a multi-section trigger. (The current config is a rear-mounted single-window hall sensor and stamped trigger wheel, which is difficult to service and notorious for connector issues).
The flywheel is a 60-2 configuration. I can machine an ignition rotor replacement with a 6-1 configuration pretty easily.
My question, since under the circumstances I can make just about any configuration here that I want, what cam trigger reference do you find to be ideal for the most flexible use with multiple controllers, and do you prefer a mild steel target, or embedded magnets for maximum signal reliability?
The sensor will be oriented in the 90deg position, so will be reading the "face" of wheel, versus the edge. Current concept here without the tooth deleted:
Very few aftermarket ECU's will work with a missing tooth crank and multitooth cam unless you closely duplicate an OEM pattern. So for your application the best options would be either just a simple single cam tooth or a single long cam tooth that is high for 180deg and low for 180deg. The advantage of the "long tooth" option is some ECU's will sync quicker with that option. Note there is no advantage with having more cam teeth as an aftermarket ecu is only using that sensor to determine what phase of the 4 cycles the engine is in.
As for the sensor itself my suggestion for a cam sensor is hall effect for best compatibility with a wider range of ecu's. This is because reluctors will output a very low voltage at distributor speeds when the engine is cranking slow and some ecu's have very little options to adjust the arming threshold etc.
Edit - I missed the bit about the magnets. Definitely avoid the flying magnet type. Stick with a sensor that has the magnet built in (most do) and use a soft mild steel as the target. The flying magnet type are more work (all magnets need to be inserted same polarity etc), less reliable, and they dont give any advantages (until you get up to large diameter trigger wheels and want to use aluminium).
Simple single window sync is easy to implement, and I can change the rotor design pretty quickly. The sensor shown is a Honeywell SNDH-H3C-G03 hall sensor, so will work with any ferrous target material.
I do some industrial controls, where having a multi-segmented wheel gives confidence to the integrity of the flagged event (missing tooth) because the timing between the predictable teeth can be analyzed for erroneous patterns. Sometimes it bleeds over into my thinking for car stuff too.