Rough Idle F90 4 Stroke EFI

[msuspartan1994]

I have a 2006 F90 4 Stroke EFI that runs rough at neutral idle (900 RPMs), it will stumble and rebound without stalling. It seems like the ECU is compensating for something. It continues to slightly fluctuate even if I increase the throttle in neutral. Maybe thinking the idle control could be acting up. The motor while underway above 1500 RPMs is smooth and has plenty of power. But I certainly have some kind of an issue going on that is mostly noticeable while idling in neutral. Is there any way to check the sensors without a computer? Thanks in advance for any advice on this.

 

[melaatik]

Re: Rough Idle F90 4 Stroke EFI

Any replies how this idle problem was solved?

I have exactly the same problem with my F100 -06.

 

[melaatik]

Re: Rough Idle F90 4 Stroke EFI

Neutral idle of Yam F100 -06 fluctuates between 600-700 rpms. That can clearly noticed by listening the engine and also from tachometer that shows fluctuating numbers 6 and 7. Also similar fluctuating can be noticed with higher rpms about 1500-2500 (in neutral).

Spark plugs, filters, and gasoline are already changed. No water was in the tank or in the filters. What should I do next? I was thinking if the reason could be some dirt in the injectors, but maybe the cleaning of IAC valve would be better thing to do first because the tank and filters were pretty clean?

 

[melaatik]

Re: Rough Idle F90 4 Stroke EFI

Yamaha F 100 hp - YouTube is showing exactly the same two symptons that I have in my F100:

1. Fluctuating idle (1:10-1:16). This is pronounced due to the squeeling side noise.
2. Squeeling side noise (all the time). I wasnt able to get it silent despite I lubricated the drive shaft and the bushing properly.

Today I checked the thermostat but it was not clogged or contaminated. Also it opened correctly when tested in heated water. The next step will be to clean IAC (idle air control) valve.

I would appreaciate to get any hints regarding IAC and above mentioned symptons.