I'll start with a simple question, which someone may know the answer to, then elaborate below - I warn you, it's a bit long winded!!
On a 1990 MX-5/Eunos/Miata, what are the key components that need to be live when the key is turned from 'on' to 'start' in order to get a 'spark' and the car start up, i.e. why can I jump start my car in 'on' but when I turn to 'start' - and the starter motor DOES engage - do I get no spark / car doesn't start?
It's not starting (no spark when key turned to 'start'). Engine turns over, can hear fuel pump hum into life, but no spark/firing up. We've already replaced the Cam Angle Sensor and Igniter, we can see these are fine because with the key in position 'on', if we turn the CAS, we get a spark. In fact, we can also jump start the car in 'on' position... so it's just turning the key to to 'start' that doesn't work.
We figured it could be the aftermarket immobiliser playing up - but we've found the only 2 wires off the back of the ignition switch that we cut/go via the immobiliser and have re-joined them/bypassed the immobiliser (I can now
get power in 'on' without using the immobiliser key fob) - still no joy/spark in 'start' though.
Took the ignition switch off, pulled it apart, cleaned the contacts and reassembled... no difference. Also checked the wiring diagram (http://www.madracki.com/miata/wiring.html
) and this forum
and touched a wire from the white to the black/blue as suggested - and it fires the starter motor (I can hotwire a car, cool!). Still no spark/starting though!
It has an aftermarket ECU (Adaptronics) but that appears fine, connected up the laptop and everything looks fine.
Don't think it's the coilpack, once started runs fine.. (this issue was intermittent with starting for weeks but now has given up completely).
All the fuses in the engine bay look fine... checked the main 'INJ' relay and this engages in 'on' and stays engaged in 'start'...
I've also borrowed my Dad and his multimeter to check the blue connection from the ignition is live on the coil pack connection and the ignitor connection in 'on' position, we thought turning to 'start' may go via a fuse or relay that was broke and perhaps we would loose the power to the ignitor/coilpack - but it's still present.
So what else needs power?? The coilpack/ignitor have power (at least from the blue ignition wire - should I check another wire?) when the starter motor fires, so why is there no spark? What is the different between jump starting
the car in 'on' position - which works - and firing the starter motor with 'start' position? I assume something else isn't getting a signal/power, what should we check?
I appreciate that the 'on' position is different to the 'start' position in that it's not just everything in 'on' plus starter motor, other things will turn 'off' to avoid drain on the battery, so only the minimal components required are live.
I figured that we could run a live signal straight to the starter motor in the 'on' position and, in theory, the car will actually start??? BUT: can't easily get to the starter motor/work out which wires I would have to touch... and it's not the 'proper' solution...
If anyone can help please, this has been driving me nuts for several weeks now, I'm not electrical or even that mechanically minded, had a lot of peoples help and thank god for Google but at the end of my tether now :(