SOHC.co.uk Forums > CB500/550

Anyone using an oscilloscope?

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K2-K6:
We were taught to use them at school,  also used at work for setting up various machines too. I'm not that skilled with them but have been extremely useful in cars for EFI systems, when you get very obscure faults people give up and just guess that the ECU is "faulty" without really understanding the true fault.  Whenever I've tested ECU output I've not found a faulty one, but many other minor things like sensors and control devices.

I'm intrigued by the spark length and form as displayed in those above currently,  it seems to have far more impact on combustion process than is initially viewed from what I'm finding.  Basically I  don't believe the " huge fat spark" is of any significance, but always forwarded as desirable.  Ultimately that's another thread really  though.

K2-K6:
Orcadian,  is that "Roverguage" you are using for the following?

"I use my laptop with an interface for watching in real time the engine management system on our MG RV8 (made before OBD diagnostics) and it's been a real help when there was a lambda fault."

If so,  do you have any reliable lambda trim value percentage data for yours that you could post?

Many thanks.

Orcade-Ian:
Hi K2,
Yes, the software is Rovergauge.  If you are familiar with it there is a bar graph for each lambda trim - left and right banks and at start up the system is open loop - no lambda values being used but at 75 degrees on water temp it goes into closed loop and uses the lambda value to adjust the fuel trim.  There is also a 'set key' for fuel trim in different markets.  You can see the bar graphs changing in real time as the ECU tries to keep the value close to 1.  Ours ran fine when cold but felt like someone had hold of the rear bumper as it warmed up!  At 3000rpm it goes back to open loop by design and it was off again like a scalded cat - very light car with a 3.9 V8 EFI motor!
I run rovergauge on my old Windows based laptop and can't remember if I can do a screen dump like I can with this ipad - someone might know.  The car is tucked away in the corner of the workshop at present so not possible to connect to the port on the car  but if you are in no rush I will certainly investigate when it takes to the road again in early Spring.
As you say - really the subject of another post or PM - I don't suppose it's a subject of interest to many!

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