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My 2003 Ultra between 2000 and 2500 RPMs has a flat spot, miss, sounds like lean pop, Cannot steady state cruise at that RPM. is fine below and above. Is a new thing after the bike was in the shop for a while. Bike is stock, shop said buy a tuner and tune it but the bike is stock and was fine for the 14 years I have owned it. it has air filter and exhaust, but has been fine with those with no tune. Could the stock ECM "lose it's tune". Seems wrong. I see used ECMs for $200. But seems weird the ECM would be out of tune for 500 RPM between 2000 and 2500 RPM. Looking for ideas what it could be NOT ECM related. Seems stupid to dyno tune a stock bike. Thanks in advance
My 2003 Ultra between 2000 and 2500 RPMs has a flat spot, miss, sounds like lean pop, Cannot steady state cruise at that RPM. is fine below and above. Is a new thing after the bike was in the shop for a while. Bike is stock, shop said buy a tuner and tune it but the bike is stock and was fine for the 14 years I have owned it. it has air filter and exhaust, but has been fine with those with no tune. Could the stock ECM "lose it's tune". Seems wrong. I see used ECMs for $200. But seems weird the ECM would be out of tune for 500 RPM between 2000 and 2500 RPM. Looking for ideas what it could be NOT ECM related. Seems stupid to dyno tune a stock bike. Thanks in advance
An ECM doesn't lose a tune, but many of the components (sensors, seals, air filter, fuel filter, etc) that play a part in allowing the ECM to maintain the proper AFR, will degrade and wear over time. Many may eventually need to be replaced, especially on a 22 yr old bike.
It it was fine, then the issue started when you got it back from a shop... Gotta ask, what was it in the shop for? What did they do?
Last edited by hattitude; Oct 20, 2025 at 01:23 PM.
Pretty sure all the ULTRA models in 2003 were fuel injected. No oxygen sensors.
What did they charge you for a speedometer calibration?
Can they modify that?
If they didn't sabotage something, (Did they quote you for the tune?)
You said..... 'flat spot, miss, sounds like lean pop'
A miss should throw a code. Is that lean pop when you come off throttle?
I would check the throttle position sensor with my ohm meter. (It's not an expensive part..$40.)
PS.. Start basic. Replace Airfilter and sparkplugs. Use Harley branded plugs. Your ping sensor is ION sensing.
Just opinion but leaks in manifold seals or fuel filter is probably not the issue. They would show up at idle big time with idle control issues. But are worth checking but I would pursue them in the right order.
Last edited by Jackie Paper; Oct 21, 2025 at 08:18 AM.
i did not think the ecm could have a flat spot. The shop was doing stereo, tires, etc. Speedo calibration, cruise.
It has been my experience, that when an issue suddenly appears after I have done a service or repair, most often it was caused by something I fixed, touched, or bumped during the service/repair.
I don't know for sure what tables or how they were adjusted for the "Speedo calibration, cruise" repairs, but it suggests they were in the ECM.... I have to wonder if they messed with something (on purpose or accidentally) that affected the tune portion...
Unless there was a misunderstanding between you & the shop, for them to suggest that you retune an OEM bike that was running well previously with the current tune, gives me pause about the level of their competence.
Last edited by hattitude; Oct 21, 2025 at 09:13 AM.
So the speedo calibration is on Dakota Digital gauges that have been on the bike 10 years, the thinking was maybe the speedo was off affecting the cruise that was not working. Yes I tend to think it is something they fixed causing the issue as it was fine going in. However it was having an issue stalling sometimes if I let the throttle off quickly and went straight to idle, but would be fine when I restarted it. They fixed that, but maybe caused a new issue? No they did not quote a tune. it sounded like they did not want to F___ with it and denied the flat spot was as bad as it is. It is not so much letting off, it is accelerating if I am easy on it going through that 2000 range, and steady state cruising in that range. Is fine if I drive it like I hate it and low through that 2000 rpm range. Below and above 2000 are good. I kept all the paperwork of what they did. I will send it to another shop. I found out a couple nights ago the ignition was not locking with the key, and also had the speedo stay lit when I turned the bike off. Turned the ignition on and off again and it was fine. So there are some issues. Trying not to get pissed and go buy a new bike. But my bike is supposed to be a source of pleasure, not pain!
That stalling coming back to idle throws it into a total new light.
It's lean anyway at idle. Why I said what I said in my first post.
They may have just cleaned around butterfly in the throttle body since that's half the idle. Rest is from IAC valve at top of throttle body.
It could be fuel filter lowering fuel pressure, slight leak in manifold seal, or a rotted cap on the throttle body small pipe for the hose for the California carbon canister. (My 04 fell off and it lost idle control and motor dieing coming to idle. Did the same when I got some bad gas.
Last edited by Jackie Paper; Oct 21, 2025 at 04:49 PM.
So the speedo calibration is on Dakota Digital gauges that have been on the bike 10 years, the thinking was maybe the speedo was off affecting the cruise that was not working. Yes I tend to think it is something they fixed causing the issue as it was fine going in. However it was having an issue stalling sometimes if I let the throttle off quickly and went straight to idle, but would be fine when I restarted it. They fixed that, but maybe caused a new issue? No they did not quote a tune. it sounded like they did not want to F___ with it and denied the flat spot was as bad as it is. It is not so much letting off, it is accelerating if I am easy on it going through that 2000 range, and steady state cruising in that range. Is fine if I drive it like I hate it and low through that 2000 rpm range. Below and above 2000 are good. I kept all the paperwork of what they did. I will send it to another shop. I found out a couple nights ago the ignition was not locking with the key, and also had the speedo stay lit when I turned the bike off. Turned the ignition on and off again and it was fine. So there are some issues. Trying not to get pissed and go buy a new bike. But my bike is supposed to be a source of pleasure, not pain!
You have a bike with Stage I mod, and never bothered to tune it for the increased airflow. Don't get mad at the bike, issues are to be expected on an engine not properly tuned for its components.
You originally said it was "fine for the 14 years I have owned it" before they touched it.
Now you say, "it was having an issue stalling sometimes if I let the throttle off quickly and went straight to idle, but would be fine when I restarted it."
The 4 bikes I currently own (all various mod stages w/tunes) and all my previous bikes did not stall "sometimes if I let the throttle off quickly and went straight to idle." IMHO, that is not running "fine", but something that should have been addressed over the last 14 years.
So it's probable you had an issue before you took them the bike. There are several possibilities for your reported issue on a well tuned vehicle. On a modded, untuned vehicle, it could be one of those possibilities, the tune itself, or years of running lean that could cause your issue.
Unfortunately, I will not be able to help with a diagnosis on your bike. It would be hard to tell the difference between what could be caused by years of running on a lean tune, or caused due to other mechanical issues. It would be almost impossible for me to tell the difference from second hand reports via the internet.
It sure seems like "they did not want to F___ with it". So you learned something valuable about the shop you used.... probably time to look for another shop.
Good luck with your repair.
Last edited by hattitude; Oct 21, 2025 at 09:43 PM.
So the bike left the dealer brand new with the air filter and slip on and no tuning was done . The stalling was something that developed well after 100,000 miles of having the mods from new. The engine has never been open except for the preventative timing chain tensioner. The stalling was very intermittent, and the shop cured that but I do not see what they did on the invoices. But never ever had any issue at any rpm before. Always pulled and cruised smooth. I thought the idle stall issue could be the IAC simply because I could instantly restart it and it was fine, as if the IAC was reacting slowly. I completely forgot the bike got a new fuel pump and filter on this trip to the shop, maybe the fuel pump someone mentioned could be the issue, it acts like it is starving in that RPM range. I got caught up in traffic in Daytona last weekend and it did seem a little hotter than normal but I have not rode it in months so I was thinking maybe I was just being a *****! Everything that has been said, it seems the new fuel pump seems like the place to start. I am going to find a different shop. I am disgruntled about why the ignition is not locking also, that was a total surprise in Daytona, not like any bikes get stolen in Daytona Biketoberfest! That cut short my unattended time away from the bike. Most 2003 are ragged out, mine is pretty sharp.
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2003 ultra lean popping
An ECM doesn't lose a tune, but many of the components (sensors, seals, air filter, fuel filter, etc) that play a part in allowing the ECM to maintain the proper AFR, will degrade and wear over time. Many may eventually need to be replaced, especially on a 22 yr old bike.
