The V8 Owners Forum -

I always like a nice chart It looks like you're getting good data there.

Another update on this.

I have 2 MAP sensors working not (it's only a 2 cylinder bike) and this is the readings I'm getting.


This is similar to previous graphic but now shows readings from both cylinders, for some reason not as smooth as original readings but should still work OK.
The phasing between the reading demonstrates that this is a 90° V twin, obviously the readings can't be evenly spaced.



Not really interested in full waveform so modified to only output lowest readings, this is what I want to balance.



This is more useful. The early reading (where the red trace is higher than blue) is with the throttle closed, just before half way I started to open the throttle, to take it off the stops and it can be seen that the readings became much closer.
This has always been my issue with how some people balance carb's/TBs, they only do it on a closed thottle but this demonstrates that the balance changes as the throttles open so that the butterfly position is determined by it's actuating mechanism rather than their stops.
Hopefully they remain synchronised as teh openings become larger. Time will tell.

Can you add a TPS reading as well?

For most part you only really need to balance at idle, simply because that is where any imbalance will have the most effect, especially in terms of a stable idle and emissions etc.

But good to see that both cylinders are at least very very close to each other.

At slight imbalance at say 50% or 100%, would not even be noticeable.

stevieturbo wrote: ↑Sun Sep 18, 2022 2:23 pm For most part you only really need to balance at idle, simply because that is where any imbalance will have the most effect, especially in terms of a stable idle and emissions etc.

But good to see that both cylinders are at least very very close to each other.

At slight imbalance at say 50% or 100%, would not even be noticeable.

Personally I'd rather have things in balance when the engine is actually doing something (more than just keeping itself turning), I did make a tweak to get it running that way although only small. Just taken it for a spin and I'd say it's running just a bit smoother. But then I would convince myself of that I suppose

I agree it is interesting to see that both cylinders are close particularly across the full wave form, I guess with a bit of though and more knowledge and time than I have it would be possible to highlight other engine issue via monitoring the inlet vacuum. I think my engine is in reasonably good fettle, would be interesting to put it onto a poor engine and see what happens.

scudderfish wrote: ↑Sun Sep 18, 2022 2:07 pm Can you add a TPS reading as well?

I'm thinking of that. I think If I tap into the TPS and make sure that my system and the bikes systems are both grounded at the same point it should be able to use this sensor. Hoping to have that in a future revision.

If you look more into the diagnostics side and fault finding. Pressure waveforms are used for many things, and quite common is a pulse sensor for detecting problems.
Whether that's in the crankcase, exhaust or intake. The pulse sensor doesn't so much detect pressure, as pressure changes. So it sees any spikes ( whether up or down ) that can signify say a leaky valve, piston blowby, head gasket etc etc, that would not otherwise be detectable from just plain pressure readings.

Pico call it their "first look" sensor, as they feel it is that useful.

https://www.youtube.com/results?search_ ... ook+sensor

eg

https://www.youtube.com/watch?v=vAGDc6W_EjI

stevieturbo wrote: ↑Sun Sep 18, 2022 9:27 pm If you look more into the diagnostics side and fault finding. Pressure waveforms are used for many things, and quite common is a pulse sensor for detecting problems.
Whether that's in the crankcase, exhaust or intake. The pulse sensor doesn't so much detect pressure, as pressure changes. So it sees any spikes ( whether up or down ) that can signify say a leaky valve, piston blowby, head gasket etc etc, that would not otherwise be detectable from just plain pressure readings.

Pico call it their "first look" sensor, as they feel it is that useful.

https://www.youtube.com/results?search_ ... ook+sensor

eg

https://www.youtube.com/watch?v=vAGDc6W_EjI

Interesting and shows that I'm not schmokin' de dope afterall.
I'm surprised that the 6 cylinder firing order is 1-2-3-4-5-6 but never worked with one so not saying it's wrong.

I'd never really looked at V6 firing orders much....but some time ago came across some Vauxhall V6, and noticed it's firing order was 1,2,3,4,5,6 too. I thought it was a mistake, but not so.

stevieturbo wrote: ↑Tue Sep 20, 2022 2:27 pm I'd never really looked at V6 firing orders much....but some time ago came across some Vauxhall V6, and noticed it's firing order was 1,2,3,4,5,6 too. I thought it was a mistake, but not so.

My thoughts exactly but I have been wrong before.

I like the look of that software he's using, must have a look into that. Good to plot multiple signals at appropriate Y axis magnificaiton with different scales.

GDCobra wrote: ↑Tue Sep 20, 2022 9:16 pm

stevieturbo wrote: ↑Tue Sep 20, 2022 2:27 pm I'd never really looked at V6 firing orders much....but some time ago came across some Vauxhall V6, and noticed it's firing order was 1,2,3,4,5,6 too. I thought it was a mistake, but not so.

My thoughts exactly but I have been wrong before.

I like the look of that software he's using, must have a look into that. Good to plot multiple signals at appropriate Y axis magnificaiton with different scales.

Just looks like a regular Snap On scope

Any decent scope will let you do it, you wouldn't need to stretch to the likes of Pico, although it is regarded as the best for automotive.

I've a much cheaper Rotkee scope which is ok

stevieturbo wrote: ↑Tue Sep 20, 2022 10:11 pm

GDCobra wrote: ↑Tue Sep 20, 2022 9:16 pm

stevieturbo wrote: ↑Tue Sep 20, 2022 2:27 pm I'd never really looked at V6 firing orders much....but some time ago came across some Vauxhall V6, and noticed it's firing order was 1,2,3,4,5,6 too. I thought it was a mistake, but not so.

My thoughts exactly but I have been wrong before.

I like the look of that software he's using, must have a look into that. Good to plot multiple signals at appropriate Y axis magnificaiton with different scales.

Just looks like a regular Snap On scope

Any decent scope will let you do it, you wouldn't need to stretch to the likes of Pico, although it is regarded as the best for automotive.

I've a much cheaper Rotkee scope which is ok

Ah, cheers. I thought it was software on a PC.

It looks a lot like the Snap On Zeus, general diagnostic scan tool with built in scope. Not cheap by any stretch !

Any PC software would still of course require the DSO oscilloscope to go with it.

Rotkee, same as MTLab Ukraine/Russia. Seemed a sensibly priced starter. I still want a Pic though.....just cant yet justify the money for a toy

https://rotkee.com/en/category/automotive-diagnostics

Ditex offer some too, Bulgaria, but there are UK suppliers

https://autoditex.com/products/

And of course Pico

https://www.picoauto.com/products/autom ... t/overview


There are loads of other scope setups out there, with costs varying wildly. I also have a cheap Hantek, but the software really is poop. But same with everything, the more you use it, the more you'd get familiar with it and it's little quirks. But I couldn't even figure out how to save a waveform and review later...if it is even possible. Which is a huge reason anyone would buy such a scope, so you can save complete waveforms to review !
a DSO isn't much good if it cannot store lol