S2 Crank but no start. Low d09

[jomor147]

Disappointment..

 

[Gary in NJ]

That’s a very inconsistent spark.

 

[Motogiro]

Disappointment..

Throw your scope on the negative side of the primary of the coil supplying that spark.

 

[jomor147]

I will do that. I will also check voltage drop between battery + and coil positive supply.

New spark plugs and eBay coils are on their way too.

Voltage drop between battery- and chassis is 0.014V so the main ground seems ok. Even though I have improved the ecu ground (voltage drop from 0.25v went to 0.07v with extra wiring) I would like to check all other grounding points, but I can't locate any. The only one i have found is behind the instruments cluster (S2 half fairing version). There are two grounding "spiders" near the ecu which I have cleaned but I was not able to locate and follow the wire that actually goes to chassis. Any other known grounding points?

 

[jomor147]

I fitted a new battery.
Voltage drop between battery positive and coil positive is 1V. It should be lower IMHO. I also replaced the spark plugs which I gapped at 0.6mm - 0.65mm. I also installed a set of used coils I ve got from ebay. I cleaned the caps interiors and made sure I have connectivity as shown here

The bike started instantly but I am getting misfires on cylinder 4. Same cylinder I was seeing intermittent sparks with the spark tester.
Cylinders 1,2,3 have approximately the same temperature while cylinder 4 is about 90°C cooler. What does this tell us
1) bad command from ecu? ( should #1 have the same issue?)
2) bad HT lead ?
3) bad connection between HT lead on the cap or cap - spark plug? Ceramic resistor is in spec.
4) bad coil ?

 

[jomor147]

I rechecked spark plug is torqued tight and replaced the cap with one of my old coils. Same result.

 

[Motogiro]

Number 1 and 4 cylinders should have the same spark so I doubt it's an ECU control issue. Sounds like a big gap between the coil HT wire to number 4.
Maybe bypass the ceramic resistor for a test.
If it's possible to swap the 1 and 4 HT wires for a test.

 

[jomor147]

Number 1 and 4 cylinders should have the same spark so I doubt it's an ECU control issue. Sounds like a big gap between the coil HT wire to number 4.
Maybe bypass the ceramic resistor for a test.
If it's possible to swap the 1 and 4 HT wires for a test.

All caps were dismantled, cleaned and tested for continuity before fitting. Back screw, spring, resistor = exactly the resistor value, end brass terminal and spark plug contact = 0 ohms. Caps are ok, firmly screwed at the ht lead of which the inner strands were exposed, straightened and cleaned before screwing the cap. My car mechanic suggested to swap injector 4 with 3 for example to see if the cold cylinder moves. What i haven't be able to inspect is the ht lead connection to the coil side. I chickened out removing the holding clip.
I can always put back the old 1-4 coil to check the temperatures, I should have tested this before, but i haven't. I still have much to learn.

 

[Motogiro]

Switching Injectors sounds logical except I thought you were experiencing a spark issue at #4 but not #1