low RPM stumble
 

My 2015 RX3 17300 miles w/300cc kit seems to have developed a low RPM stumble when first warming up. After I get going and out on the road runs great. It's not real noticeable but when I'm just tooling around the parking lot in 1st gear like I'm trying to do low speed maneuvers it bucks a little. Get the RPMs up and runs good. Any ideas? I'm wondering if something electronic is carboned up or dirty sending bad voltage to the great whoever that makes all things go goodly?
How do you check for codes? turn key on /off 5x? Do you let the fuel pump complete its priming ? thanks rj

Have you done the obvious such as cleaning the air filter and changing the spark plug?

Stepper motor passage not clean super clean
Gently wire brush the nose of stepper
It’s not holding idle to throttle correctly so the transition from stepper to throttle isn’t right

Calvarez, not yet but I will, been busy and havnt checked it much since the Moab ride.
NBL, thanks I'll clean that also since I don't think it's ever been done.
rj

How many miles are on the plug? On another forum, we're having a discussion about what a huge difference it makes to put in a new one on most bikes, and how the specified interval is often too long. And if you ride in dirt, that filter will clog up fast.

I'm watching this...mine won't hold idle speed until warmed up. Just started, too, right after an oil change. I thought that might be related, but I'm leaning toward just a coincidence right now.

Same question... Have you done the obvious such as cleaning the air filter and changing the spark plug?

Good point; work in progress.

So, in the process of cleaning the air filter and checking the plug, I found the plug wire just hanging loose, disconnected. How I got home yesterday I'll never know, but somehow the rubber plug boot was too deep and springy and wouldn't allow the plug tip to stay connected to the wire. I know that rubber can swell when exposed to oil, and I've had a little oil seepage from the valve covers since my last valve adjustment. I cut off about 3/4 inch off the boot, seated the wire, cleaned & gapped the plug and cleaned and oiled the air filter. The bike now starts and idles without issue. New plug and wire are on order. I didn't mean to hijack your thread, RJ, but maybe this will help someone else.

mckayprod , Good on you. I'm going to go check my plug wire now. Mine just has a little stumble in 3rd going through town. I cleaned air cleaner, not very dirty and plug was replaced 3200 miles ago.

So NZ, can you give me a quick instruction on where the stepper motor is and how to clean it good? I assume its on the throttle body but not sure where or how to get it out. Does gas tank need to come off? I have looked around and tried to find the info but keep running into dead ends. And well...………………………………….I'm lazy. thanks, rj

take seats off, remove the 4 stainless screws holding plastics on and the 1 tank bolt remove tank n wire hoses (5 min job)
Directly below you will see the throttle body take it out remove black stepper motor clean clean clean the passage with Q tip brake clean etc and gently scrub the styepper nose. check throttle plate closes off correctly reassemble and reset ECU.

Thanks NZ, you the man, really enjoying the 300 kit I got from you. It's added that little oomph where it was needed power wise, rj

Wait, 300cc kit and low RPM stumble...weren't there other posts about those being related? I'm not sure, just something in the back of my mind.

No not related - its common on any cc size.
The odd POP from exhaust maybe a little more common