Disassemble ISC valve

[jackmanjls]

Re: F90TLR, 2006 yama 90hp

My ISC valve has all the symptoms of being defective...won't idle but ok at WOT, ISC valve is hot, when i put into gear motor dies, don't here chatter from stepper motor when motor turned off.

The price of the part is $200+.

Can this part be disassembled and cleaned? If i can clean and save the money that's my first choice.

I've read Rodbolt17 stepper motor explanation of how the part operates and plays with the motor.

[boscoe99]

Before you do anything carefully inspect the terminals within the engine harness connector. Inspect the wires to the connector terminals. There is a known issue with the connector and the wires whereby they get damaged and the ISC valve will not function correctly.

It would not hurt to perform a continuity check on the wires from each terminal on the ISC connector back to the ECU.

[fairdeal]

try Boscoe's suggestion to check the wiring.

there is not much opportunity to "clean" the valve mechanism -
perhaps why the assembly is made with tamper-proof Torx screws -
"no user serviceable parts inside"




here is the valve dis-assembled to the point of non-functionality -

[jackmanjls]

Fairdeal...do you know what goes wrong with the part when it fails? For such a simple part it sure is expensive.

Before I go out and buy the part I'll put the YDS on and see if it leads me to the ISC. Any suggestions that might help in the analysis?

[fairdeal]

the "Operate ISC valve" stationary test will let you see if it actuates.
You'll need to unbolt it so you can see up inside the "horn" portion

but if you remove those Torx screws for a close inspection -
don't actuate while you have it apart

[99yam40]

I think I have read about soaking only part of the ISC valves in combustion chamber cleaner helps some times.
maybe rust or carbon binding it up, but do not see how carbon would get there.

Edit maybe it was a bearing binding up

[pstephens46]

the "Operate ISC valve" stationary test will let you see if it actuates.
You'll need to unbolt it so you can see up inside the "horn" portion

but if you remove those Torx screws for a close inspection -
don't actuate while you have it apart

what might happen, Mr Fairdeal?:

[99yam40]

think he said it comes apart when he tried that

[rodbolt17]

sometimes it will toss the pintle and spring a rather long distance .

[boscoe99]

sometimes it will toss the pintle and spring a rather long distance .

Those springs, pintles, balls, etc. are surprisingly similar in colour (Yamaha silver/gray) to a concrete floor. I suspect by deviant design.

"That will teach the backyardigan to take it to 'prephessionel Yamaha mokanic' in the future."

Now why does the eye see the part blurrily flying off in direction north but never sees the turn that it then takes to the east, west, or south?

Good news is that the part is generally found in the last place that one spots it in. Hopefully, it is not the eye.

[boscoe99]

Spring loaded parts flying towards ones face "are generally closer than they appear to be'.

[jackmanjls]

Not taking it apart...I'll replace if required.

To be clear...the question that I'm trying to answer is the ISC valve defective and need replacement?

I connected the YDS up to the F90TLR and ran the static and active tests.

The static test has a parameter called: ISC valve opening. For the 3 secs the test ran the [%] values were something like 0->16->64->70. I also listened to the valve for the motor to step. It sounded like it did but step cleanly. I don't have the "tribal knowledge" to determine if it's the correct sound.

I did video tape the sound but it's in .mp4 format and this forum doesn't support it. Might there be someway I can get that vid to the forum...it's 600Mb after compression.

The active test has 2 parameters that I question, they are: Throttle valve opening (0-90), ISC valve opening. Both are 5sec in length.

I've added a .mp3 link for the audio and .mp4 link for video. If the link doesn't work as depicted then copy to the browser and run.
https://www.dropbox.com/s/ua4h01kny3...et%29.mp3?dl=0
https://www.dropbox.com/s/weuimat9p0...CTest.mp4?dl=0


I'm assuming the first is suppose to have upper and lower limits on the 0 to 90 range. My value never changed from 7.1.

The second parameter casually change from 15, 16 to 17 and back. I left the test run for at least 45 secs.

My first guess would be that the valve is defective but I'm not sure.

Any suggestions?

I have videos of all testing and I did save most of the other test in .csv format.

[rodbolt17]

when you execute the active test did the RPM increase?
remember that % number is a REQUEST. does not mean the valve actually moved.

[jackmanjls]

The active test ran was the "Angle of ISC valve opening".

The test was run for 43 secs and there was none/slight increase in rpm.

Should I run the "Fully open ISC valve" test or is the Angle test sufficient?

[pstephens46]

Run the other test too. Fully or 100% should increase rpm a good bit. Hard to recall, maybe up to 2000rpm on an F150