Hi,

No, nothing has changed in this part of the code for a long time.

The bumps at the end is caused by excessive retardation just after the max RPM. If you check the wheel HP/Torque you will see the negative part at this RPM range being high before stabilizing. This may happen if you for example let the engine brake the rollers for a very short period of time at the end of the run.  

Hi thanks for your reply

very confused then - ended up having to raise the rev limiter to catch the rpm window I wanted.

run as inertial but always finish run with clutch down and into neutral, unless its an auto in which case getting a good coastdown can be a bit weird (but understandly so)

edit: I generally keep the clutch down until stationary, I havent rally changed my procedure here

anything else you can think of that might cause it mate?

Post the pic with the retardation run (let's see the wheel hp/torque).

will do though might be a few days before im at the workshop again 

sorry for such a late response on this

I've not been at the workshop all week due to commitments elsewhere, managed to get another car on to do a test yesterday and today - the car yesterday didn't exhibit the issue though todays is doing it regularly. Seems a bit weird can't see what im doing different - ideas on a postcard?

It is definitely excessive braking around max RPM limit. Right-click and choose "Set scale to default" to see the whole graph, and you will see it on the negative part of the wheel graphs. Can you post the pic?

Hi it should be attached to the last post? or do you need something else?

Yes, same graphs, but you need to zoom such that you see the negative part. Right-click and press "Set scale to default".

sorry, just typed out a lengthy reply and the forum doesnt seem to have saved it.

I managed, to find my way to seeing the dip, it is there - (note to self, open wheel graph before zoom to default) - it is there.

I'm not blaming the software but what could cause this? i made a concious effort to end the runs properly and yet it seems to affect some vehicles particularly, not always the ones i would have expected, for example had a dsg the other day auto transmission and its hard to avoid a bit of engine braking at the end of the run as to get to neutral i go in two moves, yet i didn't see it. had a car on earlier manual usual no problems and it exhibited the issue, had another on since and it was fine.

if this is more down to the vehicle being tested is there any way to avoid this as opposed to running to higher revs and manually cropping the graph?

You have an inertial dyno? It is more common on a brake dyno, if you push the clutch before the brake turns off at the end of the run. The brake will quickly regulate to turn off, but it remains on for a short time time depending on the brake setup and PID parameters. For anyone with a brake dyno having this issue, either wait to push the clutch until the brake is off (may be risky for some engines) or press the "Coast now" button exactly at the same time as the clutch is pressed. 

For auto cars and cars with more complicated gear boxes, it is hard to know exactly what happens. Somehow the rollers are retarded by something at the end, different from car to car. 

You can use the graph editing to smoothen the bump out. 

yeah it's inertial (for now anyway!)

just trying to avoid the jumps on the curve, sometimes customers ignore my staff only signs and ask 'whats that!' before i have time to clean up

allright for engineers because they can envisage whats going on in the workings of things but public want clean runs every time *rolls eyes*