Quote:
Originally Posted by Jpc647
It was more of a, how does that pin have power with the key on, if it's not connected. And, that must mean that cylinder isn't firing.
|
That disconnected terminal has power because it's connected to one side of coil. Other side of coil is connected to +12v. Imagine replacing coil with piece of wire with 2 terminals, if you connect one end to +12v, other end would have +12v also right?
Since one side of coil is disconnected, no current flows, therefore no voltage-drop V=IR. Voltage is same on both sides of coil. Until disconnected side is grounded by ignition box. Then black wire drops to zero volts (see scope trace above).
Issue you want to track down is whether that coil is
receiving grounding pulses. Oscilloscope is alway my first choice because it shows not only binary yes/no "yeah there's pulse alright" like 'noid light, but it also gives me
quality of signal such as duration and completeness of grounding pulse. Which can help narrow down issues with shorted wiring or bad coil problem.
For now, just plug disconnected wire back into terminal and see if it runs smoothly on both cylinders.
If not test for spark: pull plug-wire, stick known-good plug into it, ground case of plug by laying on top of engine, then crsnk engine. Also do test on other cylinder as control.