I need some help getting my vvt motor running, I've gone over my wiring 2-3 times now and it all seems correct. So far all I can tell is I'm not getting spark and don't think I'm getting any signal from the crank sensor. I'm terrible at diagnosing electrical stuff, so if anyone is able to chime in and help out I'd appreciate it. Car is a '90 chassis with brain-built ms3x, engine is '02 vvt, the megasquirt worked fine with the previous 1.6 in the car.

 

well your right, your not getting any crank signal. have you check the sensor gap on the crank? did you change the wheel decoder settings in MS?

 

Yes and yes, gapped the sensor with a credit card. Could it just be a bad sensor? Is there any way to test that the sensor works?

 

waving a metal object in front of the powered sensor will generate a voltage change on the signal wire.

 

So, I checked wiring again, all voltages appear to be correct, went ahead and replaced the sensor just to see if that would do anything and still don't have crank signal.

 

You say voltages are correct, your red/white wire on the harness going to the crank sensor has 12 volts when the key is on run?
The black/light green ground wire has a hard 0 for voltage when compared to the block? I would also check for resistance, should be very low.
Check the resistance of the white wire all the way back to the MS. it should be very low. If it is then your wiring is correct and the problem is in the MS or the sensor.
(these colors are guesses based on the VVT swap thread sorry if I made a mistake)

Sounds like a new sensor did not replace your problem, maybe look again at the megasquirt. perhaps adjusting the trim pots?

Did you try Y8's suggestion? might be hard to set up if you do not have the right equipment. You might need an analog voltmeter to see the needle move.

 

Sensor has 12v, testing the sensor by waving a screwdriver in front of it goes from 4.9v to .9v. I have not checked resistance, but I'm gonna have a look inside the ms to make sure all the correct jumpers are installed. Should anything be different for it to use the nb sensors? It previously worked fine on my 1.6 with cas.

 

Trigger pattern needs to be miata 99-05 instead of 4G63.

 

Already changed

 

Were you measuring the signal voltage at the ecu? If it was at the sensor I would measure again at the megasquirt.

 

Just checked and got the same voltage at the sensor connector as i get at the ecu connector (.9-4.9v).