|  | Topic : Adjusting stepper and TPS |  |
| | | Shannona1989 | | Set |  |  | | Reg. Date | : | 16/08/2022 | | Posts | : | 49 | | Location | : | Geraldton , Western Australia , Australia |
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| | Posted : 01 May 2026 - 09:48 Post title : Adjusting stepper and TPS | | | Having an issue with adjusting my stepper motor and tps, I get my bike idling beautifully and the shut her off, give it 10 mins and re-start her and my idles all up to shit. Left throttle body hangs around 270 and the right throttle sky rockets to around 410 its really got me scratching my head. Ive replaced the tps and the map tubes. Ive been repeating this process well over 10 times. Any advice? Cheers
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| | | Leethal | | Zeus | | | | Reg. Date | : | 24/01/2011 | | Posts | : | 6,608 | | Location | : | Australia |
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| | Posted : 01 May 2026 - 12:10 Post title : Re: Adjusting stepper and TPS (Re: Shannona1989) | | | What software are you using to adjust the tps etc?
| Experience is something you get just after you needed it 
1600,Foran Razorbacks, Meerkat bypass, Dyno tune, real headlight,plenty of chrome,switchblade pegs, Nitron R3 shocks & Ikon progressive fork springs etc. Scorpion Western Low handlebars. PH adjustable fork caps.
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| | | Shannona1989 | | Set | | | | Reg. Date | : | 16/08/2022 | | Posts | : | 49 | | Location | : | Geraldton , Western Australia , Australia |
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| | Posted : 01 May 2026 - 16:43 Post title : Re: Adjusting stepper and TPS (Re: Leethal) | | | Using tuneecu on a samsung s25+
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| | | Leethal | | Zeus | | | | Reg. Date | : | 24/01/2011 | | Posts | : | 6,608 | | Location | : | Australia |
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| | Posted : 01 May 2026 - 22:55 Post title : Re: Adjusting stepper and TPS (Re: Shannona1989) | | | Ok this is AI and I agree with most of it. Check your map tubes are not pushed too far into the elbows, this can block vacuum causing all sorts of issues. AI from here on. Based on your description and the symptoms on your 1600 Thunderbird, the issue of the idle going "all up to shit" after a 10-minute soak is a classic symptom of the stepper motor (ISC) failing to properly reset or a mechanical binding in the linkage.Given you have already replaced the TPS and MAP tubes, here is a focused approach to fix this:1. The 10-Minute "Hot Restart" CulpritIf the bike runs well immediately after adjustment but fails after being shut off, it is likely that the stepper motor is not returning to the "home" position.The Fix: When you turn the bike off, listen closely for a humming/whirring noise coming from the right side of the throttle bodies (the stepper motor). It should move to the "closed" position about 30 seconds after shutdown. If it doesn't move, it is likely sticky or faulty.2. Physical Check (Crucial)Lubricate Linkage: Ensure the linkage that the stepper motor acts upon is free from debris, clean, and lightly lubricated.Check Stepper Lever Gap: The clearance between the idle speed control lever and the roller on the throttle cam should be \(0.5\text{mm}\). If this is wrong, the stepper cannot control the idle, leading to wild fluctuations.3. Proper Adjustment Procedure (Using TuneECU)If you are using TuneECU, ensure you are following the sequence exactly:Warm Up: The engine must be at operating temperature (\(\sim 90adjustment.
| Experience is something you get just after you needed it
1600,Foran Razorbacks, Meerkat bypass, Dyno tune, real headlight,plenty of chrome,switchblade pegs, Nitron R3 shocks & Ikon progressive fork springs etc. Scorpion Western Low handlebars. PH adjustable fork caps.
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| | | Leethal | | Zeus | | | | Reg. Date | : | 24/01/2011 | | Posts | : | 6,608 | | Location | : | Australia |
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| | Posted : 01 May 2026 - 23:07 Post title : Re: Adjusting stepper and TPS (Re: Leethal) | | | If you are using TuneECU, ensure you are following the sequence exactly:Warm Up: The engine must be at operating temperature sim )).Adjust TPS First: With the engine off (ignition on), set the TPS voltage to between \(0.58\text{V}\) and \(0.62\text{V}\) at closed throttle.Use "Adjust ISCV" in TuneECU: Do not just turn screws. Use the "Adjust ISCV" test in the "Tests" tab to lock the stelpper motor while you set the idle balance, then allow it to run properly.Balance Throttle Bodies: Ensure the HPA readings are close, but focus more on the TPS voltage and stepper positioning.4. Forced AdaptionAfter adjustments, you must force the ECU to learn the new settings:12-Minute Tune: Start the engine from cold (do not touch the throttle) and let it idle until the radiator fan comes on. Then, let it idle for another 12 minutes.5. Check for Vacuum LeaksEven though you replaced the tubes, ensure the MAP sensors themselves are functioning correctly, as a false reading will cause the ECU to drive the stepper motor to the wrong position.If the stepper motor does not move, it might be necessary to replace it, although failure is rare compared to simply needing cleaning and adjustment.
| Experience is something you get just after you needed it
1600,Foran Razorbacks, Meerkat bypass, Dyno tune, real headlight,plenty of chrome,switchblade pegs, Nitron R3 shocks & Ikon progressive fork springs etc. Scorpion Western Low handlebars. PH adjustable fork caps.
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| | | MotorMac | | Jupiter | |  | | Reg. Date | : | 29/08/2010 | | Posts | : | 1,958 | | Location | : | Nor Cal, United States |
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| | Posted : 09 May 2026 - 05:19 Post title : Re: Adjusting stepper and TPS (Re: Leethal) | | | Is TuneECU still available - or is there something better?
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| | | Leethal | | Zeus | | | | Reg. Date | : | 24/01/2011 | | Posts | : | 6,608 | | Location | : | Australia |
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| | Posted : 10 May 2026 - 07:39 Post title : Re: Adjusting stepper and TPS (Re: MotorMac) | | | Yes but it's now a pay for use platform. Nothing other than Dynojet tuners afaik.
| Experience is something you get just after you needed it
1600,Foran Razorbacks, Meerkat bypass, Dyno tune, real headlight,plenty of chrome,switchblade pegs, Nitron R3 shocks & Ikon progressive fork springs etc. Scorpion Western Low handlebars. PH adjustable fork caps.
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| | | MotorMac | | Jupiter | | | | Reg. Date | : | 29/08/2010 | | Posts | : | 1,958 | | Location | : | Nor Cal, United States |
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| | Posted : 16 May 2026 - 15:12 Post title : Re: Adjusting stepper and TPS (Re: Leethal) | | | Sorry to hear that, Lee. Horrible business model, like another utility bill.
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| | | Leethal | | Zeus | | | | Reg. Date | : | 24/01/2011 | | Posts | : | 6,608 | | Location | : | Australia |
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| | Posted : 19 May 2026 - 23:08 Post title : Re: Adjusting stepper and TPS (Re: MotorMac) | | | No problem, I have the old free version on an ancient laptop but I rarely use it these days. I had mine Dyno tuned a long time ago so no need to mess with it anymore. There doesn't seem to be the same amount of interest in self tuning these days anyway.
| Experience is something you get just after you needed it
1600,Foran Razorbacks, Meerkat bypass, Dyno tune, real headlight,plenty of chrome,switchblade pegs, Nitron R3 shocks & Ikon progressive fork springs etc. Scorpion Western Low handlebars. PH adjustable fork caps.
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