I've just installed my freshly built MS2 into a 1995.5 Miata and I'm having an issue with getting a good cam signal. Here's the background (a bit long winded) but just to make it easier to diagnose.
I performed the tach input mods as described by DIYAutoTune's documentation. I.E.
1. Jumper Tachselect to VRIN & TSEL to VROUT
2. CMP (pin5) to JS10 with a 1k 1/4w resistor inline and a 5v pullup (470 ohm 1/4w from 5V proto)
3. CPK (pin24)
4. VRIN with a 5V pullup (470 ohm 1/4w from 5V proto)
I have the crank and cam signals both in shielded wires with the shields grounded to pin#2 on the DB37 and run completely separate from the rest of the harness. These wires run through an empty heater core hole to the MS (mounted on the firewall) while the rest of the wires route through the factory grommet all the way on the passenger side of the car.
TunerStudio ignition settings are as follows:
Spark Mode: 4G63
Ignition input capture: Falling edge
Spark output : Going low
# Coils : Wasted Spark
Spark A output Pin: D14
Cam input: Cam input
When using the composite logger the check the cam and crank signals I have a nice consistent squarewave from the crank sensor. However, the cam comes in as an impulse or spike. See screenshot below:
Has anyone seen this before? I've tried adjusting the pots (R52 and R56) with no success. Lowering R56 beyond 5 turns clock wise and the crank signal disappears. I started with R52 all the way counter clockwise. I kept turning up to 8 turns clockwise and no change. I'm getting to the end of my rope here and have no idea what I'm missing. I also tried rising edge with no change to the log. Any help from some of the MS experts or someone who has had this problem and fixed it would be greatly appreciated!