2014 Yamaha f115lb idle rpm too high

[Troutbeast]

Hi all,

Me again. I’m having a small issue with the idle being a bit high on this f115lb. It is not the cable adjustment as I have removed the cable end to test. It is running at 900-1000 rpm when warm. I have a feeling it is the ISC valve. I tried lowering the rpm in the *****ing mode but it would not go below 900. I can go up from 900 to 1100. In *****ing mode I should be able to lower it to 600 I think. Would this be a sign that the isc valve is not moving it’s full range? If so would this not throw a code? There are no codes present.

Thanks
Steve

[TownsendsFJR1300]

When turning off the engine(easier to hear with the cowl off), do hear a "clicking" for about 2- 3 seconds?

You should as its the ISC re-setting. Advise.


.

[99yam40]

the ECU does not monitor the position of the ISC, it just sends a signal to move.
if it dose not move and keeps getting signals to change it can overheat the ISC and the ECU circuit

[Troutbeast]

Hi, Thanks for the replies. I will listen for the noise next time I'm at the boat and report back. have not noticed it previously.

That's great info. I think it is moving, but not through its full range, It is worrisome that it could fry the ECU. I better check it before running again. Is there any way to repair/clean it? Or replace only?

Thanks
Steve

[TownsendsFJR1300]

I re-call reading that it should NOT be getting very hot as it's just a stepper electric motor.

[99yam40]

I re-call reading that it should NOT be getting very hot as it's just a stepper electric motor.

I agree to a point, but if the ecu keeps sending signals to step and it does not , and it keeps sending the signals over and over to make some reading it looks at change that does not change.
I have a feeling the stepper is not designed to do that type of duty

[Ferris11]

I'm just chiming in after remembering an older post about a high idle.
According to Rodbolt in a previous post: "if any sensor is out of range it idles about 1100. Any sensor failure, out of range or left unplugged after service will cause a high idle.
A YDS printout at idle might show that"

[Troutbeast]

Thanks for the info guys, this is all really helpful! I don't have access to the YDS diagnostic tool (is there a way for a non-dealer to buy it?). If a sensor is out of range would it not throw a code? I have no codes present when i look with the command link meter.

I probably should have mentioned this before, this engine has been underwater. I have changed the engine harness and a few sensors. Seems to run well and has not thrown a code for the 7 hours I have run it since the harness replacement. Just the high idle.

After looking at how the ISC works it is very possible that it is seized or has a tight spot. The idle does change when i use the *****ing mode, but i wont go below 900 rpm. It will go up to 1050-1100 with *****.

I will try to get down to the boat soon and check the ISC

Steve

[TownsendsFJR1300]

ISC working: https://vimeo.com/264625510

[Troutbeast]

Ok, report time.

I started the engine and shut it down a few times with no clicking noise from the isc. I then removed the isc and opened it up and plugged the motor unit back in. Then started the engine and used my finger over the intake port to control the idle speed. The unit did not move even though I was changing the speed by allowing more or less air in with my finger. This is a sign that isc hooped I would say.

Now another question. I unplugged the isc and ran the engine with the isc still in the system. Obviously no idle speed change, it stayed at 900. Also no alarm saying that the isc had an open circuit. Is this normal? Some here mentioned that if the isc was stuck it could burn out the ground path in the ecu, is this a sign that may have happened?

Thanks all

[99yam40]

it is a possibility
why not test it with a meter to see what you can read

[Troutbeast]

I didn’t have my meter with me. I will test it next time I’m down.