2011 Street Bob stalling when warm – losing my mind
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6th Gear
Joined: Oct 2025
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2011 Street Bob stalling when warm – losing my mind
2011 Street Bob (FXDB). Relevant mods: ThunderMax Gen 3 ECU, Red Shift 575 cams, HPI billet throttle body, Vance & Hines Big Radius exhaust, Arlen Ness inverted air cleaner, Scorpion clutch basket
My ’11 FXDB runs perfect cold, idles great, rides strong for the first few minutes. Once it warms up, it stalls every time I roll to a stop (clutch in, roll off throttle → idle dips lower and lower → dead). I can feather the throttle to keep it alive, and it always fires right back up after cycling the ignition (thought it was a fuel problem and this was priming the pump, but it seems more ECU reset now). The hotter the day, the quicker it happens (I think the bike just reaches temp faster on hotter days).
Fuel pressure holds steady at 58psi at all times. Pump, regulator, filter, check valve, fuel line, TPS, IAC, head temp sensor, and speed sensor all replaced. No intake leaks. ThunderMax Gen 3 ECU, autotuned. Idles fine on the stand, never stalls unless it’s a rolling stop after warm-up.
Anyone seen this exact pattern? Temp-related (I think) + only happens rolling to a stop.
Symptoms:
Bike runs like a champ cold. After warm-up (within minutes of taking off), stalls only on rolling stops. Idles fine on the stand, no loss of power under throttle, and fuel pressure is rock solid. Issue seems temp-related and possibly tied to how the ECU/IAC handles idle recovery.
Has anyone run into something similar? Any direction on where to look next (tuning/IAC tables, wiring gremlins, O2 behavior when hot, etc.) would be hugely appreciated.
My ’11 FXDB runs perfect cold, idles great, rides strong for the first few minutes. Once it warms up, it stalls every time I roll to a stop (clutch in, roll off throttle → idle dips lower and lower → dead). I can feather the throttle to keep it alive, and it always fires right back up after cycling the ignition (thought it was a fuel problem and this was priming the pump, but it seems more ECU reset now). The hotter the day, the quicker it happens (I think the bike just reaches temp faster on hotter days).
Fuel pressure holds steady at 58psi at all times. Pump, regulator, filter, check valve, fuel line, TPS, IAC, head temp sensor, and speed sensor all replaced. No intake leaks. ThunderMax Gen 3 ECU, autotuned. Idles fine on the stand, never stalls unless it’s a rolling stop after warm-up.
Anyone seen this exact pattern? Temp-related (I think) + only happens rolling to a stop.
Symptoms:
- Starts and idles great cold. Runs perfect for the first few minutes.
- Once warmed up during a ride (just a couple minutes), stalls consistently when rolling to a stop (clutch in, decel → idle drops lower and lower until it dies).
- Can be kept alive by feathering the throttle.
- Always starts right back up after cycling the ignition/kill switch, idles fine again until the next rolling stop.
- The warmer the ambient temp, the sooner the issue appears (½ mile in the 80s, ~1 mile in the 70s, ~5 miles in the 60s). Very repeatable.
- New fuel pump (OEM Harley unit installed by dealer).
- Replaced pressure regulator, filter, check valve, and fuel line.
- New TPS, IAC, speed sensor, head temp sensor.
- Upgraded to Gen 3 ThunderMax ECU, autotuned.
- Verified fuel pressure steady at 58 psi under all conditions (idle, WOT, decel).
- Cleaned/verified IAC pintle movement, throttle body, and air filter.
- Inspected harness, moved wiring away from rear head, cleaned grounds, and checked connectors - hit everything with CRC QD.
- No intake leaks (tested with carb cleaner).
Bike runs like a champ cold. After warm-up (within minutes of taking off), stalls only on rolling stops. Idles fine on the stand, no loss of power under throttle, and fuel pressure is rock solid. Issue seems temp-related and possibly tied to how the ECU/IAC handles idle recovery.
Has anyone run into something similar? Any direction on where to look next (tuning/IAC tables, wiring gremlins, O2 behavior when hot, etc.) would be hugely appreciated.
2 things come to mind to check.
1) Throttle stop screw backing out - not uncommon. IAC steps at hot idle should be about 30ish. If they are very high, the screw has backed out and you need to turn it in while the engine is warm and running.
2) Is your speedo and turn signal cancelling working properly? Loss of the speed sensor input will cause failure of ECM to position IAC properly on rolling stops.
1) Throttle stop screw backing out - not uncommon. IAC steps at hot idle should be about 30ish. If they are very high, the screw has backed out and you need to turn it in while the engine is warm and running.
2) Is your speedo and turn signal cancelling working properly? Loss of the speed sensor input will cause failure of ECM to position IAC properly on rolling stops.
Thread Starter
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6th Gear
Joined: Oct 2025
Posts: 12
Likes: 4
2 things come to mind to check.
1) Throttle stop screw backing out - not uncommon. IAC steps at hot idle should be about 30ish. If they are very high, the screw has backed out and you need to turn it in while the engine is warm and running.
2) Is your speedo and turn signal cancelling working properly? Loss of the speed sensor input will cause failure of ECM to position IAC properly on rolling stops.
1) Throttle stop screw backing out - not uncommon. IAC steps at hot idle should be about 30ish. If they are very high, the screw has backed out and you need to turn it in while the engine is warm and running.
2) Is your speedo and turn signal cancelling working properly? Loss of the speed sensor input will cause failure of ECM to position IAC properly on rolling stops.
I am unfamiliar with with a backstop screw on the throttle body - do you have a diagram or can describe where it is (HPI 51mm) - I'll give that a check.
Today, I cleared all data, loaded a fresh map, did the IAC reset calibration (30 seconds on / 30 seconds off / 3 times), and then let the bike get to full temp (over actually 300 degrees) with auto-tune on. It sorted itself out with the new map idling on the stand - hopped on the bike and it stalled at the first stop sign like clockwork. Always in gear, always coming to a stop... cycled the ignition, starts right back and idles fine - put it into gear off it goes, come to a stop, stalls. so predictable - you'd think this would be an easy one to diagnose. Going crazy over here.
It is literally the screw that the throttle plate bell crank stops on. Look where the cable attaches to the throttle body. If it is backed out, the IAC is open too much and cannot compensate for fast recovery when needed. Like I said, aim for about 30-35 IAC steps at idle. if you back the screw out it will raise iac steps, if you turn it in, it will lower IAC steps.
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6th Gear
Joined: Oct 2025
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It is literally the screw that the throttle plate bell crank stops on. Look where the cable attaches to the throttle body. If it is backed out, the IAC is open too much and cannot compensate for fast recovery when needed. Like I said, aim for about 30-35 IAC steps at idle. if you back the screw out it will raise iac steps, if you turn it in, it will lower IAC steps.
What year iac is on the throttle body? The pinnouts are different starting in 2006 one piece throttle body.
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Thread Starter
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6th Gear
Joined: Oct 2025
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Sent data logs to ThunderMax, they said the ECU might be fried – did the Gen3 upgrade, new map, new auto-tune – seemed to fix it sort of, ran like garbage, eventually started running better and better over 500 miles or so auto-tuning it – but still stalled constantly (same behavior, slowing to a stop, stalls every time). Chased it as a fuel problem for a while (swapped the regulator, check value, hoses, filter, o-rings), bought a fuel-tool to rule that out completely – 58psi rock solid. Tried a new map, tried to reset the IAC (30 secs on/30 secs off), cleared learned offsets – tried again… problem persists.
So predictable it seems engineered to do it – cold bike? No problem. Warm bike? Stalls when coming to a stop every time. The stalling behavior happens quicker when its warmer out – on a nice cool day, I can ride a bit longer (by longer, I mean a mile or 2 instead of half a mile) before it hits temp and starts stalling.
Apologies for rambling – really at my wits end here.
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Thread Starter
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6th Gear
Joined: Oct 2025
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Likes: 4
OEM direct replacement - 2011 - I did read something about having to swap 2 wires, but not applicable here.
please post a oic of the iac on the throttle body. The wires may be the issue.