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my car is running extremely rough during idle and misses horribly during acceleration. in an attempt to identify the issue i unplugged all sensors i could access from topside, and i found that when i unplug the crank sensor (located near the pulley) everything seems to run smoothly again. thinking the crankshaft position sensor faulty i ordered a new one but observed no improvement, the issue remains. once again i went over the engine testing various ground points, fuses, etc. finally i checked for voltage from the crankshaft position sensor plug off the harness and i receive an extremely weak output signal instead of the target 5v.

can anyone suggest some possible causes for this?

vehicle info:

1992 Mazda MX-3 GS V6
HEI Ignition Mod w/ Blaster Coil
New 10mm plug wires and NGK Iridium spark plugs
Coolant Temp Sensors replaced (both)
TPS replaced and tested within spec.
New O2 sensors (both)
SS Autochrome Headers
Custom 2.5" exhaust mandrel bent piping.
DIY Cold Air Intake
VAF cleaned and tested within spec.
EGR cleaned
IAC cleaned

Do you have any CEL codes? If the crankshaft sensor wasn't giving a code I don't see a need to replace it, and yes the car will run without it - I've confirmed that, but I don't think it's your issue. It might be just a secondary thing covering up the real problem. You need to start with the basics: figure out codes (since you unplugged everything you'll definitely have some codes now), check to make sure your timing is accurate, etc.

was the HEI mod done recently ?

where did you get 10mm wires?

the HEI mod was done several months ago, ran fine for quite some time. There's a CEL code now for most everything that was unplugged: knock sensor, coolant temp sensor, TPS, and...crank sensor (02), but there were no codes at all prior to pulling said sensors. the plug wires were purchased from eBay along with the spark plugs, something I had bought intended for use with a KLZE that hasn't happened yet (Also it turns out they are 9mm, i confused them with the 10mm wires that are on the 240. oops). My roommate decided to install them when one of my old plug wires went faulty (during the HEI mod actually) and they've stayed on since.

obviously, the car will run with the sensor unplugged...hence the title of this thread. But you can't pass GA emissions with a check engine light on, and i'm uncertain if it will pass emissions in it's current state (say, if i were to pull the bulb out of the cluster).

At this point I want to check the resistance and voltage from the ECU-side of the harness, but I can't seem to locate a wiring diagram to help me identify the correct wires. the online repair manual does not include the wiring diagram surely someone on this site has some knowledge of the ECU pinout.

my next trip to the pull-a-part yard will likely include a few ECUs to test and play with...but i'm running out of money and without a car it's hard to find work. i'm dying here guys, i could really use some sound advice.

Check your timing points. Timing is off.