Hey guys, im having a bit of problem with my F4.

Im not getting any spark to cylinder nbr 4.
I checked the coil in another position and it fires, ive changed the plugs and ive removed the wiring to the coils and checked for continuity.

Is there a way to check and see if the ECU is sending the signal to the coil to fire? Was planning on sticking a test light on the signal wire and see if it pulses but didnt want to incase that would damage the ECU.

What could cause this problem, dont have a replacement ecu to check so hoping to rule that out esp since its only on nbr 4

thanks

 

There is a way to check the signal, however it would require a meter that can capture Peak voltages. The signals are of very short duration and a standard meter would only read millivolts.

 

Thanks Idodirt. Another question for you. Seems after lots of research my plugs wires are routed incorrectly. The way the are now, nbr 1 is on the right (Clutch side) and nbr 4 on the left (stator side). Yet I'm seeing that the correct firing order is opposite (1 by stator and 4 by clutch). What confuses me is somehow the bike still runs. So which is the correct order and if its wrong now how come it still starts, runs and revs out....

 

Cylinder pistons 1&4 are usually up at the same time and 2&4 are down at that time. There is just a slight difference in timing between 1&4.

 

Without cam-sensor, no way to differentiate TDC compression vs. TDC exhaust positions. So ignitor does wasted spark and fires #1 & #4 simultaneously, then #2 & #3.
You've confirmed coils are good by swapping them and having no-spark stay on #4. Let's do further testing to find potential causes of no-spark on #4

1. key ON/kill=RUN, measure power at blk/wht power wire at #4 coil-connector, volts=??? (compare to other cylinders for verification)

2. check for ignition-triggers on #4 trigger wire.

Let's assume trigger wire is continuous between ignitor connector and coil connector. Normal test-lights won't work because duration is way, way too short. Can use

solenoid test-light

solenoid test-light

to see if there's grounding trigger signal. It has duration extending circuitry to keep light on long enough for human eyes to see. Would look like this on oscilloscope, high (battery-voltage) most of time, then periodic ground-pulses from ignitor to create spark.