Weird throttle issue at 4Krpm 2009 xb9sx

[JonDredd]

Sometimes as I'm cruising in 3rd or 4th gear, and am steadily climbing through rpm, when I get to about 4K the power will drop off, or just hold as I am giving it gas, and will kick back in a few moments later if I give it more. I have noticed this a few times, and probably happens about 30% of the time when I'm riding. Some days I don't notice it much at all, and other days, it is much stronger. It never really stalls out, but the power just is not there, and I give it more until it kicks back in, and after I'm near 5K rpm or more, it is totally fine. It only seems to happen at around 4000 rpm or so. I'm trying to figure it out, and rule out possibilities now. I was getting a CEL weeks ago, but it was due to a loose battery connection, and I have had no CEL since I fixed it. I also suspected the quality of fuel, but I have been to a few different locations to fill up and the issue seems consistent with all. Why would it only be happening around 4K rpm?

[user_deleted]

you'll likely be receiving many "needs seafoam"...."faulty fuel pump"...."bad coil" responses. the symptom you described happens with some frequency to the 2008-2010 XB models and can often be traced to the IAC unit which is mounted to the TB and controls curb idle speed and "just-off-idle" throttle response. i have never determined precisely how it plays into sluggish mid-rpm roll-on throttle response but it does in many instances. if performing this task yourself you'll have to remove air cover, airbox inner lid, filter, base plate AFTER disconnecting IAT sensor which reveals the TB and IAC unit. remove the unit, clean the pintel valve and the port on the TB it seats into extremely well with gentleness....then reinstall. often times cures your malady. if not in all likelihood your pump providing sub-standard pressure to the injection system.