Test car: 1992 Mazda Miata 1.6
Trigger: Cam angle sensor, 4 primary 2 secondary at cam speed
Must use these types of settings to ignore one of the secondary triggers: http://www.vems.hu/wiki/index.php?page=MembersPage%2FFero%2FMitsubishiEVO
Other notes:
Injectors are paired up in the factory harness. This is horrible, but no changing it for plug-and-play
Fuel pump is controlled by the air flow meter, so we used a P-ch mosfet to switch 12V to pin 1C which drives the coil of the fuel pump relay that is used when cranking in the stock application.
Intake air temp sensor is located in the air flow meter - we supplied an extension to GM style open element air temp sensor
There are many different engine variants in the Miata NA family. This should apply to the 1989-1993 segment. Later engines had a crank mounted primary trigger and ECU controlled fuel pump.
Problems:
Minor, but annoying is cranking takes 2.5-4 seconds to sync. Fires right up after sync and it starts signaling the coils, but the very long crank is noticeable and gives a poor impression. Not sure what can be improved here without looking at both rising and falling edge of secondary trigger to see if it's the "long" window or "short" window.
Prior problems that are solved:
ECU voltage is accurate with ignition on, engine not running (~11.7V) - With engine running ecu displayed voltage is very high (17V), but measured voltage at ECU input is normal 14.4V. ECU on bench calibrates perfect with lab power supply. Trying to identify the problem here.
- Solution was to replace R13 (75k) R6 (22k) and c4 (100nF) - found that R6 was broken and had too high of a resistance. Extremely uncommon. The R6 resistor was approx 38k even though it was labeled 2202 which is 22k. Likely a mechanical break that got worse with vibration and moving the board around.