Poor running between 2000 and 3000rpm

[nelsonRzh2]

I have a PCV and sprint filter , full Akrapovic exhaust. I had SLR do my ECU flash and a local shop do my dyno tune. The  ZH2 runs great!!

[John_A]

Mine is a 21 SE, and haven't got any of this poor running at any low revs.

I would expect at low throttle openings and 2-3K revs the ECU to be running in closed-loop (ECO sign on the dash)
Could it be that the narrowband oxygen sensor has been contaminated and it 'hunts'?

[SaltyStream]

I have experimented with letting the ECU handle the fueling at cruise/low throttle (aka IAP tables active).
On my Z H2 I have the O2 sensor active via the Zeitronix NB output.
This works just as well as it did on my B-King when I was tuning that bike with Woolich and Zeitronix.
It takes lots of time and numerous re-flashes to get the same result tuning IAP,  as just letting the ECU/O2-sensor logic keep the AFR at a rate that give excellent fuel economy *and* good "driveabilty".
This might be different for different engines/bikes/ECU "logic".
In my case I let the OEM ECU logic handle AFR at "cruise". I can see via my Zeitronix gauge that it keeps the AFR to 14.7, which the Z H2 is perfectly happy with.

I know that many tuners/tuning community state that a AFR at 13.5 or similar is what to "strive" for at any given speed/throttle opening, but I beg to differ.
This is actually a over-rich condition, but rich fueling will just make the throttle response smoother which most riders like.
I prefer "big numbers" at full throttle paired with excelling mileage which I now have with my Z H2.

The "jerky" or "poor" fueling around 2k - 3k rpm on my Z H2, I can verify is when the ECU switches between closed vs open loop as the AFR jumps from 12 to 17 in this area. I also suspect logic for PAIR might have something to do with it, but in my case that should not be the case as I have blocked the hose (Still the PAIR valve is open and dilutes the fueling as there will be an area where the intake valve will get "polluted" air via exhaust).

I might experiment a bit more with this area, but for now I just change gear to keep the revs out of this range.
Not sure if it is worth the effort to disable the O2 sensor and use a lot of time adjusting the IAP tables via countless (and a small risk) re-flashing of ECU. BTDT with the B-King. Not worth the time for me at least.

[JD]

Just for giggles I set my cruise control at 21k in 3rd and let it putt around And it was unflappable smooth, even a little uphill. When I reapplied throttle there was no hiccups or anything it just pulled.
I don’t ride in that many parades anyway.

[Marco]

Rev it to 21K and you'll not be riding it anywhere ever again 😁🙄

[JD]

ha I guess I meant 2.1k
Fun fact the ZH2 will idle in 6th at 18mph

[SaltyStream]

On the way to track day yesterday I noticed that this issue with "ruckeln in schieb-betrieb" is exactly as the germans describes (best).
No issues on steady throttle/cruise on even roads or when the engine is under load (on such low revs).
This only occurs when going downhill and "coasts" ("shieb-betrieb"), and the ECU goes from certain transitions in IAP tables.
Not sure if it is worth the hassle to eliminate this.

[ESR]

Originally Posted by SaltyStream

On the way to track day yesterday I noticed that this issue with "ruckeln in schieb-betrieb" is exactly as the germans describes (best).
No issues on steady throttle/cruise on even roads or when the engine is under load (on such low revs).
This only occurs when going downhill and "coasts" ("shieb-betrieb"), and the ECU goes from certain transitions in IAP tables.
Not sure if it is worth the hassle to eliminate this.

I agree, at least on my bike it is not so significant it is worth to look at.
Some people may a little sensitive to noises and vibrations possibly, don't know.....
I have no problems, it has no real influence, the bike is smooth as butter in slow city traffic.
I am not too clever, but couldn't it be a low chain tension that magnifies the engine reactions at low revs 

[John_A]

Also let's not forget that these are the revs where detonation is most likely to occur.
Having a high gear, very low revs and going full throttle is begging for it.

https://www.cycleworld.com/story/blogs/ask-kevin/engine-rpm-and-low-octane-fuel/

[Christiaan]

Originally Posted by nelsonRzh2 link=topic=931.msg8229 :028:#msg8229 date=1659215485

I have a PCV and sprint filter , full Akrapovic exhaust. I had SLR do my ECU flash and a local shop do my dyno tune. The  ZH2 runs great!!

We are all jelly….