quick question about what sensor controls injector firing

[crazyrog17]

Someone else mentioned in the thread, the camshaft position sensor is in the distributor. The coil wouldn't be firing if the CPS wasn't sending a signal to the computer so that leads me to wonder if the injectors are getting their +12v.

[dueces]

I always assumed the spark was delivered completely mechanically since the disty is driven off the cam, timing it, or does the ignition module have to see a signal to know when to allow the coil to fire?

[dueces]

But yeah ill check for 12v at the injectors and use the test light

[KingFish]

http://www.fordfestiva.com/forums/showthread.php?t=39496

This thread has a chart that list all the inputs to the ECM and what they effect. Including Injectors.

[dueces]

Do you know what years that is for? I've looked on my motor(89), and on the motor out of the 90 that I parted, and neither have a Crankshaft position sensor.

[KingFish]

Cps is in the dizzy under the steel dust cap.

[Damkid]

^^That would be a CAM positioning sensor, not the Crank sensor

[dueces]

Ok thanks guys. After checking the injectors that's where I'll start looking.

[KingFish]

Crank position is inferred from the cam. Just more stuff lost in the translation form the Mazda shop manuals.

[Team Lightning]

You can have the plugs firing without the injectors firing. I had that issue on my 93.
I had spark but the injectors were not firing. I changed the disty and it fired.

[dueces]

RI have already replaced the disty. and now i have checked the injectors and i do not have 12v to them so i think i will try to find the wires at the ecu and make sure its working, besides that i dont think it would be anything else.

[Damkid]

I was about to offer to send you some festiva wiring diagrams to try and help out... but i realized yours is an 89' which would be different then the diagrams i have

[georgeb]

I have an '89 wiring manual. Looks like they get power from the main relay. Several devices are spliced into the power wire. Do know if checking for 12V at the injector is the right way to do it? I am led to believe you need a noid light.

[Movin]

You only need a noid light to see the ecm side flash while it is running.
A led test light works the same.
A standard test light will show power from the main relay
It will show bright-dim while cranking with a good battery.
A weak cranking system will show bright-dim every where
because the starter bucks each cylinder. Don't confuse a week
battery/starter/connections for the injector being fired by the ecm.
That is why a noid light is better but not necessary.

[dueces]

Well while i was messing with it i put a test light in an injector connector and it never lit up