Ford Ranger 2.9l No Spark From Coil

[bigmanpapachuska]

Hey, I have been struggling with this for a while and couldn't find anything that was helping. I have a 1990 Ford Ranger 2.9L, manual transmission. I have replaced the coil and plug wires because I had no spark off of the coil. Still no spark off of the coil. I do have 12V going into the coil when key is in auxiliary. When I use my test light to check the switching signal while cranking, I get a dull glow off of it. I read that on these TFI motors the ECM does not control the spark when starting, and that it only recommends spark advance. Could I be looking at an issue with the TFI or hall sensor? Or is the dull glow the switching signal and I have an issue somewhere else? Thank you for any help I get!

 

[RonD]

Only the TFI controls the spark based on Hall effect sensor inside the distributor
Yes, Computer can change Spark advance(timing) but not whether or not coil sparks

When you disconnect the SPOUT wire, that disconnects Computer completely from TFI

An ignition Coil works by giving it 12volts(+) and a ground(-) to "power it up"
This creates a magnetic field around the Primary coil, "coil" is what it sounds like, just a coil of wire
Inside the primary coil is the Secondary coil
The 12volt magnetic field causes a much higher voltage to build up in the Secondary coil
Lower amps but higher voltage, it not "free power" lol
Say 12,000volts in Secondary

When you cut ground or 12v on the Primary the magnetic field collapses so the 12,000v is released, so Sparks
Since the early days of gas engines with a spark plug the ground(-) was cut to cause spark from the coil, 12v stays on until key is off
And that's still used today even in 2023

Back your vehicle
With key on coil gets 12v, AND should be grounded by TFI module, thats its normal state, coil's (-) is grounded
If you were to put a test light on coils + and - it should flash while cranking engine over, as the TFI module ungrounds the - wire
It will dim because battery voltage drops to under 10v while cranking engine, but should flash/flicker

Cranking speed is abut 200rpm, and there are 3 sparks(V6) for each 1rpm, so that's 600 sparks per minute so about 10 sparks per second, so flicker is more accurate than flash, lol

Google: How to test an ignition coil/module with a test light (distributor ignition)

Watch the video
They didn't mention it but when testing coil + wire you hook test light to Ground or battery negative
When testing coil - you hook test light to 12volt or battery positive, and will get the flicker as seen if its being ungrounded
GM or Ford doesn't matter all ignition coils work the same, even coil packs and COP

If you don't have flicking then TFI module would be the next stop
The Hall effect sensor in distributors rarely fail but thats not never fail

Another thing to check before all this...................see if distributor rotor is turning, there is a gear on the distributor shaft that can come loose, so no spark because distributor shaft is not turning when engine is cranking