Individual Cylinder Power - usefull tool

[Pet]

Hi,
  we have tuned Ford Siera Cossworth and there were problems with missfires on higher boost levels. Many things were replaced, without success. Then we have discovered individual cylinder power graphs And what we saw; two cylinders had missfires. Once again checked ign cables, plugs..... And.... two plugs (and cables) were "drilled" by HV. There isn't to much space between silicone ign cable and head cover and something was wrong here. Anyway here are logs with/without missfires.

1st; with missfires:

2nd; plugs and cables replaced:

[gunni]

I use it all the time if I feel the car is having a problem of some sorts.
Compare the overrun traces to the running traces to see which cylinder is having problems,

[Pet]

Maybe question for Gunni I am not sure, how to recognize excatly, which cyl has problem. Because when there is wasted spark and only primary trigger (crank) I don't know, which cylinder is on power stroke (if 1 or 4 ?) Am I right ?

And about cyl identification: (from V3 help)
•Ignition output0 is measured always in INDIVIDUAL POWER2
•for 4Cylinder:
•Ign_out0 ->individual power2
•Ign_out1 ->individual power3
•Ign_out2 ->individual power0
•Ign_out3 ->individual power1
(more here http://www.vems.hu/vt/help/v3/datalog/individual_power.html)

But on my engine, I have:
Ign_out4 - cyl 2&3
Ign_out5 - cyl 1&4

Then how to recognize cylinders in Individual power graphs ? thanks.

[gunni]

You won´t be able to , you´ll be able to identify the cylinder pair, which solves half of identification from 4cylinders.

I´m not sure on how ignition power 2 being IGN0 and you not using it relates to finding it out, I´d just pull an injector and see how it behaves.
You can also just uncheck an injector in the injector outputs while the engine is running, that would show you which one is off for instance.

[Machismo]

I got excited about this individual power stuff, I have a V8 and when I turned the individual power gauge on it showed all 8 cylinders bouncing around at idle. Then I increased rpm to 2000 and 3000 and the display stabilized showing some cylinders a bit stronger than others. At that point I assumed it works since it looked convincing... Then I disconnected one cylinders coil which made one cylinder went dark. But it didnt change anything! All cylinders still according to the gauge were active. Why it does not work?

I then red this

https://www.vems.hu/vt/help/v3/datalog/individual_power.html

There is info about the association of the numbers, but no mention of 8 cylinders. Why the info is missing, is it supposed to work? I have a 60-2 trigger wheel, 3.6 board and latest firmware etc. So little information available about this subject, please enlighten me. I really would need this to work to be able to tune my engine better.

Oh one more thing, if I just power on Vems, some of the individual power gauges start to bounce erraticly, where does that come from? They should be at zero when the engine is not rotating.

[z0tya]

Individual power works only when knock real time data disabled:
Vemstune Inputs/Knock Samplings/Knock real time

[Machismo]

Thanks for the swift answer.

I checked that but I had already the right selection there: "Realtime Data Option: ADC/Individ.power"

I now, just for testing put it to "Individ. knock data" which caused the individual power to stop showing anything. (like you said)

So, my problem is not that it wont show anything, the problem is, it shows mostly garbage. For example that if one cylinder does not ignite, I do not see it from the individual power display, they seem all pretty even at 2000 rpm. Only if I disconnect two cylinders, I start to see some less power in two "bars", but even then, they are the wrong cylinders.

Could it be that knock sensor would create some disturbance, should I disconnect it? I mean, if they are handled by the same circuit.

Edit: I disconnected the knock sensor, did not help, individual cylinder power readings still remain erratic.

I start to think that 8 cylinders has too many events per 60-2 trigger tooth for Vems to really see the differences between cylinders, unless of course someone can confirm that they have successfully used this feature with eight cylinders.

My 3.6 board is one of the very early ones. Could it be my hardware is not exactly the same as it should to be able to handle this?

[z0tya]

I have only experience with 4 cyl.
Could you upload some log?

[Machismo]

Yes what I was reading that people had success with 4 and 6 cyl. So those are confirmed, I think.

Sure, I disconnected now cylinder 1 which should be channel 0. Started log, started car, let it run on idle for a moment then I revved to couple of thousand rpm:

http://vems.hu/download/VemsTune/bugreports/Report-2023.09.14-21.03.19.zip

I am wondering, if you disconnect one of your four cylinders, do you see it's then completely "out" in the power display, or is there a little bit power still shown? If you have interest and have not tested without one cyl before, try it with both idle and lets say 2500 rpm.

[z0tya]

I have had a log with disconnected injectors at first the 1st cyl then 2nd and so on, but i have not found it
But your log a bit wierd for me especially the before cran section, why individual power boucing and not stay at -512usec...

[Machismo]

Yes they are bouncing "minimum to maximum" when engine is at idle and even when engine is off, there is still a bit some bouncing activity going on on some cylinder displays.