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Home FAQ Gasoline engine electrical system 
Can you help me this case; my client has a Honda Lead 110 scooter, idle speed a little bit fast, I can repair it easily if it is the old carburetor scooter. However, this is the new FI generation and I can not adjust it. People told me that I need a Motoscan equipment to adjust it, does it true?
Answer: This is a common question for us. You should know that, to repair new generation electricity system on motorcycles the repairman need to have a new knowledge a about engine power correction in the EFI control unit system as the following block diagram:
We know that, in the gasoline engine, especially PGM-FI the idle speed is designed and set up with about 1700 rpm, if this speed is wrong, it can affect on other system such as idling stop. The idling speed will depend on intake quantity through ISCV because the throttle is now closed. If this valve wide open, then the intake air is big. --> MAF is big as well --> Power/engine speed will increase and vice versa. The ISC valve of open wide or narrow depend on: - INPUT:
+ Engine temperature signal (TW)
+ Intake air Temperature signal (TA)
+ Starting status signal (STSW)
- OUTPUT: Position, width, mechanical condition of ISCV (stuck, stopped up, wore, wrong position)
- SETTING: Geometry position set up , Altitude (use for some new generation motorcycles of Honda)
- ECM: The calculation coefficient in the control programming algorithm inside the ECM

As the standard of the idle speed wrong, you should check the related factors as I mentioned above. The percentages diagnosed:
- 60% due to do OUTPUT
- 30% due to INPUT
- 10% due to ECM So, you should use the function read faults of OBD and live data function of Motoscan to locate the faults and repair or replace it and the idle speed will recovered. The ability to have faults of ECM is not much, because it would not be wrong order coefficients are calculated within the ECM, the error is mainly due to the INPUT and OUTPUT. If you do not find the faults position but force the ECM to correct the calculation coefficients so it is like "put good man into the prison instead of crime” The way to adjust calculating coefficients of manufacturer inside the ECM is as a last resort and should not overdo it.