Too lean at X rpm = herky jerk hesitation?

[Slide Panda]

I've been doing a little fussing with the my PC II and tried out a new map last night.  For the most part, it seemed to improve things, with one exception.  When I brought it up to around 5 k and held it steady (a gentile cruise), after a few seconds I'd start to get this herky-jerky feeling from the engine.  As if there were peaks and valleys in the power, while the RPM was constant.

I printed out the fueling maps that I had previously and that I loaded in.  The loaed one has significantly lower numers in the 10-20% throttle columns and the 4.5-5.5 k rmps ranges.  For example my original map read 0 at 10%/5k vs the new map of -27 for the same cell and 8 at 10%/5k with the original vs -33 at 10%/5k in the new map.

So there are some significant differences between the two maps in that region.  Would the leaner settings on the 'new' map lead to the herky-jerk feeling. 

This is my 1st real journey into mucking with my fueling, so I'm not super educated as to what fuel conditions result in what feelings coming from the engine.

[phildo]

YES,
Had the same issue with the origonal map in my U59 ecu. Really jerky at 4k just off the throttle stop. I fatened it up in that area and now it's smooth as butta. It was an amazing differance!!

[Speeddog]

Tweak those cells richer and see how you like it, that's the beauty of the PC.

It'll most likely cure that issue.

[Slide Panda]

Yeah, I just created a map that's rough average of what I had and the experiment that lead to the jerkyness.  I'll gve it a go this evenign and see if it's smoothed out.

[teddy037.2]

sounds like that should fix the prob... I'm assuming that the old map, in the same rev/throttle range doesn't have that stutter?

[Slide Panda]

sounds like that should fix the prob... I'm assuming that the old map, in the same rev/throttle range doesn't have that stutter?

The old map didn't have issues like that at all.  5K was my chosen burble along rpm when I was around town or just cruising the highways.  The ole 900 would happly hum along at 5k with my original mapping

[teddy037.2]

yep. richening up that spot should do the trick then 

[Slide Panda]

Yep, too little fuel was causing that herky jerky.  i beefed up the fuel and it smoothed out.  I went back to my previous map, since it worked well enough that I had no real complaints.  There's probably room for improvement, but I think one would need either more knowledge than I have, or a dyno... or both

[teddy037.2]

you could always adjust the fuelling in your new map to match the area of the old map and ride it like that, since you did say it seemed to be improved aside from that one dead spot...

but I'm in the same boat as you. (as yuu? ) I just sprung for the dyno tuning. although, I'm gonna have to retune now, thanks to some new mods...