cb1100 startup sequence

[max]

For some time i have puzzled over how the cb1100 " knows " where the stroke order is with only the crank sensor to work from.
Best guess i came up with is; "it feeds only one cylinder and when it fires it registers an even or uneven sequence".

Well i just used an electronic " spanner ", it's a 4 channel automotive oscilloscope "h-scope 402" with a 1 minute plus memory capacity of wave forms.
Connected spark plug no 1 and injectors 1 and 4 to the scope, started the bike and this happened.



The two injectors have a different voltage level selected, no4 is smaller so i can identify it reliably, i used only the two that i could get to easy so there might be another explanation how this works.

You can see exactly when the engine was started by the dip of the green line's voltage as the starter button was operated and the dips are the compression strokes of the cylinders when the starter button is operated.

Injector 1 opened to prime with some fuel, then after 3 more cycles it " guessed " the engine was firing in the right order, rev's were picking up pace and started injecting on all four cylinders.

All done in 0,7 seconds according to the time scale below the graph.
So it appears the sparkies all fire straight away but the ecu determines from the injector "success" if the injection order is the right one as far as i can work it out hence the three " misses " before it's happy and the rev's increase on successful combustion.

[Houtman_imp]

Max , you are a bright spark ! The light in my head is a lot dimmer .

[tommymck]

Cool topic. I'm easily confused though. Since you're only looking at spark 1, how do you deduce that all sparks are firing initially?

[GoldOxide_imp]

Just need to hack the ECU and you can tweak the "sparkies" to dance the way you want 'em.

lol - maybe a new mode to go into a real "eco mode" by firing only two-of-four cylinders.

Nice fun max.

[Lord Popgun]

I don't have the wiring diagram handy, but don't we have a crankshaft position sensor (CKP I believe). That should play in somehow.

Max, can you provide a link to this device? I can't find it by searching.

[max]

Cool topic. I'm easily confused though. Since you're only looking at spark 1, how do you deduce that all sparks are firing initially?

Tommy if you look at the pulses in between spark 1 you see a smaller spark 2.
Remember we only have two coils for four cylinders so 1 ( and 4 ) marked fire together at the same time and 2 and 3 in between, they are all there but i only marked no 1 otherwise there is too much text in the picture.
Click on the picture for a bigger version if you like.

I don't have the wiring diagram handy, but don't we have a crankshaft position sensor (CKP I believe). That should play in somehow.

Max, can you provide a link to this device? I can't find it by searching.

Yup, cps on the right hand side behind the allen key cover;



But of course it rotates twice every fire cycle and is of no use to determine which cylinder to inject fuel to fire, you could be injecting on the combustion stroke instead of the intake stroke.
In most cars a camshaft sensor is used which rotates only once per fire cycle so the ecu knows when to inject fuel based on those 2 sensors, we only have a ckp sensor.

The h-scope is a build project based around an stm32 board like an arduino and connects to an android tablet with an "otg" cable, the stm32 uses 20 mA, peanuts.


https://www.youtube.com/watch?v=B_deBfrZiSI
https://www.youtube.com/watch?v=vhsX5kqz0Ws
https://www.youtube.com/watch?v=TdVszkCzRYE
https://github.com/martinloren/HScope/bl...210327.pdf

The project has two channels but i added 2 more with stereo potentiometers configured in an "H" per channel to maintain separation so i can add signals to channel 2 and select the amplitude of them to mix and identify which signal i am looking at ( the green trace ).
The voltage drop at startup just happened and was a nice bonus.

The injectors still had the resistors in 1 and 4 connector so i clipped the probes to those and clipped a sensor to sparkplug one for the timing reference.

[max]

Here is a picture of how the scope was connected to the bike, click twice for a bigger version;

[GoldOxide_imp]

Yup . Common and economical alternative for the hobbyist-type.

Heck, even for the engineer who is too lazy to lug around the bench equipment.

[max]

Yes, here is the commercial top of the line;

https://www.aeswave.com/eSCOPE-ELITE4-wi...p9605.html

Still have to learn to drive the thing but it does some amazing things in a very short time.
Mine cost $45,00 nz not including the samsung tablet.

But not required if you have a Honda, they just don't have problems as a rule, just ask.

[GoldOxide_imp]

Yes, here is the commercial top of the line;

https://www.aeswave.com/eSCOPE-ELITE4-wi...p9605.html

Still have to learn to drive the thing but it does some amazing things in a very short time.
Mine cost $45,00 nz not including the samsung tablet.

But not required if you have a Honda, they just don't have problems as a rule, just ask.

Nice. Looks rugged (like that).

Maybe seems steep in price considering what a bench grade non-application specific scope costs.