A few months ago, my bike started to misfire at slow speeds occasionally, though it needed 10 to 15 miles ride to start misfire. Two months after the initial sign, the problem suddenly escalated to each ride; occasional misfires to frequent all of sudden. Erratic engine idle added to it as well, ONLY with rides over 20-25 miles. Summary;
1. Misfires approximately after 15 miles ridding only at low speeds (fine with anything above 4000 rpm) after a COLD startup of coure.
Note: Happens faster in a street ride than in a freeway.
2. Erratic engine idle (Video link1 link2 ) after 20-25 miles.
15 miles to misfire and 10 more miles for erratic idle.
3. Idle hangs above 2200 rpm in cold startups ONLY when #2 happens.
Sometime drops back to normal pretty quick and sometime takes a while, but it drops.
Therefore, I took my bike to a certified local dealership. First, they claimed ECU had a glitch, reset and re-programmed it. I didn’t make it home and it re-appeared right after I picked it up from the dealership, again after 15 miles! Took it back for further diagnostics/investigations. A week after, they couldn't find the problem so they contacted KTM for help. KTM, without hesitation, like a known issue advised them to replace the throttle body, and "IF" not then replace the ECU as well, AWESOME! That "IF NOT THEN" thingy really bothered me, so picked it up.
Back at home, I completely removed the throttle body, did some checks like connections and etc, some sort of TPS check (?), replaced spark plugs, checked stick coils, BGC and cleaned the throttle body. Put everything back together and MAGIC... no issues, not even a sign, very smooth, no misfires, no idle issue, just fantastic like good old days... but only lasted for 500 miles, and then the same problems! Pissed off, garaged it and didn’t touch it since then, just connected to TuneECU out of curiosity.
Passing by, I saw another SD990 in a big Yamaha dealership parking lot, waiting to be fixed. Asked about it and the dealership owner who was also taking care of it by himself was dealing with the exact same issues. He got almost same response from KTM too; to replace the throttle body. If I recall it correctly, he also mentioned something about a servo motor on throttle body which controls a rod, he believed that causes the issue. The servo motor can't be fixed, so the entire throttle body needs to be replaced. Some questions;
1. What made my bike to run so great for that 500 miles?
2. Do you think disabling 2nd butterflies can help me to identify the issue (removing and disabling with TuneECU)? I read something about it, somewhere, not my idea.
3. What about that servo motor which that gentleman mentioned?
4. Should I just replace the throttle body and stop wasting my time? The cost is matter of course.
5. What else can I do? Or if you encountered it before?
Also, I took these screenshots when I connected to TuneECU, you can see P0113 error. Can it be a potential culprit for the mess? Any thoughts about other readings? PLEASE HELP!
Sorry for English though!
