F115 IAC Valve

[99yam40]

I have read about cleaning them to help the sticking, but have no idea how well it works

[seahorse5]

Mate in Australia they are fuel injected

If that is the case, then I stand corrected. The US models have carburetors.

[JONSNELL]

Yes I tried everything ( soaking in Carby cleaner/ contact cleaner ) on the old one but no joy and from my research it seems like a lost cause. What I don't understand is how/why or with what do they become stuck ?

[99yam40]

Yes I tried everything ( soaking in Carby cleaner/ contact cleaner ) on the old one but no joy and from my research it seems like a lost cause. What I don't understand is how/why or with what do they become stuck ?

sorry, but no info from here on that

[Sequoiha]

you might try throwing it up against a wall, if it is actually stuck then there is nothing you can do, it is a drivin worm gear like a lenco trim tab acuator, could have open windings and thus not working, not stuck just not working.. try ohming out the pins and comparing it with a good one...

[RadarContact]

ISC high idle (~2,200 RPM)

the ISC valve is a simple stepper motor.
was used in both a 4 and 6 wire configuration over the years.
the 4 wire is a single speed the 6 wire is a dual speed.
at key on 12V is applied through both the fwd and rev direction windings.\

with no ground path the 12V simply sits there like a bump on a log.

to adjust the idle speed the ecu requests a % change in the ISC valve opening.

so the ecu toggles the ground and ASSUMES the valve followed the command.

which is why when you shut the key off,after the engine actually ran, you hear the ISC rattling.

at engine shutdown the ECU sends a request for something between 67 and 100% opening(model dependant) in anticipation for the NEXT start cycle.

the ECU does not and cannot monitor the ISC for a physical position nor for the fact it can even move or the circuits(wiring harness,powersupply) is good.

the ECU to ISC is a rather stupid relationship.

the ECU looks at the TPS input,crank position input and map inputs and determines ISC position for the best idle speed.

the ISC is NOT designed to have a constant on time, it has a rather limited duty cycle.

IF the idle speed does not do what its supposed to the ECU will keep sending requests and the duty cycle increases to the point where something,typically the ECU,overheats and bites the dust.

at the end of the day? the ISC valve is a DC motor similar to a trim motor.
polarity change(which windings selected) determines what way the motor runs and either extends or retracts the valve.

its not complicated,it does require an understanding of how it works.
once the ISC moves,or not, the ecu removes the ground path and the circuit is dead and the ISC stays there until its toggled again.

if it does not move the ECU does NOT know that mechanically it failed to move.
the only thing the ECU "sees" is the idle speed failed to follow the request so the request keeps being sent and the ground path toggled.

typical ISC requests will fall between about 47% to about 65% while idling,much below and you may have excess air entering the intake manifold,much above and the passages are clogged or shutters are out of sync.

Sir,
You seem to know more about this than ANYONE I've talked to since my problem started! Please help me...

I have a Yamaha Stratoliner motorcycle, and my motor will INTERMITTENTLY go into an extremely high idle condition -- sometimes right after start up, other times after I've been riding for a while.
In that condition, if I turn off the bike with the key, I hear a jamming sound from the ISC, versus the usual bzzzzz...very disturbing!

I replaced the ISC, checked all wires for continuity back to the ECU, etc. I have not replaced the TPS, yet.

Yamaha says replace the throttle body as the next step in troubleshooting this problem.

Anything I can do to find what the problem might be??

Thank you so much...help me fix this and you'll find a box of Omaha Steaks On your doorstep!!

V/r
// Radar //

[TownsendsFJR1300]

Sir,
You seem to know more about this than ANYONE I've talked to since my problem started! Please help me...

I have a Yamaha Stratoliner motorcycle, and my motor will INTERMITTENTLY go into an extremely high idle condition -- sometimes right after start up, other times after I've been riding for a while.
In that condition, if I turn off the bike with the key, I hear a jamming sound from the ISC, versus the usual bzzzzz...very disturbing!

I replaced the ISC, checked all wires for continuity back to the ECU, etc. I have not replaced the TPS, yet.

Yamaha says replace the throttle body as the next step in troubleshooting this problem.

Anything I can do to find what the problem might be??

Thank you so much...help me fix this and you'll find a box of Omaha Steaks On your doorstep!!

V/r
// Radar //

You don't have an ISC on your V2 Stratoliner, can you post a pic of what you replaced?

You should be able to check the TPS going thru the dash board.

The low # should be around 16 and high # about 100 or so turning the throttle SLOWLY.

If you have ANY SKIPPING #', missing #'s its bad. TPS's can still pass this test and still be bad.. You shouldn't have any buzzing and clicking like the ISC does normally on the OB engine.....Most of the FI'ed Yamaha's still have an idle screw adjustment even with the fuel injection. The ISC adjusts the idle per the ECU for Yamaha OB engines.

Did you check for any re-calls for the bike. The TPS was recalled for MANY Yamaha motorcycles over the years. You didn't post a year or size so you have to check ..



Here's a link for the FI for a Stratoliner (I don't know your year or model #);

http://www.babbittsonline.com/oempar...c798a2b/intake

Depending on the year, I'd be looking towards the boots that connect the 2 barrell throttle body to the heads for any cracking/ lean condition. A spark plug check for color should tell some too..

[RadarContact]

You don't have an ISC on your V2 Stratoliner, can you post a pic of what you replaced?

You should be able to check the TPS going thru the dash board.

The low # should be around 16 and high # about 100 or so turning the throttle SLOWLY.

If you have ANY SKIPPING #', missing #'s its bad. TPS's can still pass this test and still be bad.. You shouldn't have any buzzing and clicking like the ISC does normally on the OB engine.....Most of the FI'ed Yamaha's still have an idle screw adjustment even with the fuel injection. The ISC adjusts the idle per the ECU for Yamaha OB engines.

Did you check for any re-calls for the bike. The TPS was recalled for MANY Yamaha motorcycles over the years. You didn't post a year or size so you have to check ..



Here's a link for the FI for a Stratoliner (I don't know your year or model #);

2010 Yamaha STRATOLINER DELUXE (XV19CTSZB) Intake | Babbitts Online

Depending on the year, I'd be looking towards the boots that connect the 2 barrell throttle body to the heads for any cracking/ lean condition. A spark plug check for color should tell some too..

First let me say thank you, THANK YOU, for responding. I appreciate it very much.

Ref ISC: We refer to it as the ISC, and it's referred to that way in my service manual, but in parts fiches it's called a linear control valve.
Yamaha 1D7-85880-00-00 - Linear, Control Valve : Yamaha Sports Plaza

First, I'm going to take a good look at what you've wrote here before I respond...I'm not a mechanic so it may take a few passes! Lol

Meanwhile, here is a more detailed explanation of what has been going on since October of last year (in the next post/reply):

[RadarContact]

I have been fighting with this issue since Thanksgiving and have possibly ruined 3 ECUs.

It seems that my ECU remains open when it should be closing. When operating correctly, my bike should have an ECU-maintained idle RPM of 850-950 via the ISC valve. Mine starts fine but after about 15 seconds it goes up to 1500 RPMs then gets to as high as 2,500 RPMs; it throws a code of #37, "ISC valve stuck fully open".

This began after I installed my ECU again after having it reflashed by Ivan, a guy who has done this for probably at least 100 others with no problems. He took it back and tried it on his bike, and the problem happened on his as well, so my bike did something to the ECU,

But what and where do I start to fix this? First I was told to SeaFoam it, which I did with no change. Then I replaced the ISC motor with a new one but this didn't change anything either.

Ivan insisted on sending me a new ECU "to make things right" but my bike possibly damaged it as well, I guess...same problem after 25 miles. Then he sent me a third one and it did the same with it after 54 miles. I thought this was a bit ludicrous but he insisted.

[RadarContact]

Sorry, my bike is a 2007 Yamaha Stratoliner Midnight (XV19CTMW). It has the 1854cc "1900" V-twin motor.

[TownsendsFJR1300]

Sounds like an electrical issue to me. Somethings not right, the TPS wouldn't do what you initially posted.

I have to assume you posted on the Stratoliner forums with no luck?


Cliff, or username "Motogiro" IS the electrical expert on this forum I also frequent;

FZ6 Forum Community

I'd suggest joining, make up a post noting ALL the above including year, etc. Please ask for him (that I referred you,((same username)). He should be able to help. I'll PM him and give him a heads up...


**BTW, being the issue started AFTER pulling the ECU for a reflash, have you checked VERY CLOSELY the connector to the ECU, any loose wires, shorts, etc? Where ever you worked around on the bike, parts to be removed, etc, I'd re-check those area's closely.

[RadarContact]

That sounds great! Thank you.

I also just purchased a used but known to be good, stock ECU from a friend which I'm going to use as a control.

I did check all those pins, etc and put dielectric on them. It actually was "fixed" for about 2 months+ riding it almost daily. Thought it was a done deal. Then it came back.

I am just a shade tree but I agree, I think it is electrical...in particular a grounding issue if I had to guess. I don't know how to check for shorts; I am not proficient with a multi-tester except for DC volts and continuity.

I am ALL OVER every Strat & Yami bike site out there. I'm probably a #1 google hit if you type in "ISC high idle"!! Lol. (either laugh or cry at this point)

I pick the bike back up from the dealer tomorrow, but I have guests staying here this weekend. I will edit the info so it is better organized and do what you said with motogiro.

Again, thanks for taking an interest.

// Radar //

[TownsendsFJR1300]

The dealer couldn't find anything???

BTW, I PM'ed him already...

[rodbolt17]

after all that. its NOT an ISC nor an ECU issue.
find out what is calling for the idle speed request.
not familiar with bikes but EFI is pretty much EFI.

why does the bike idle high, the ECU doesn't get a correct RPM signal possibly.

[RadarContact]

The dealer couldn't find anything???

BTW, I PM'ed him already...

No, they went through the standard checklist I've already (tried to) run.

Here's what the service manual says are the possible causes:
"Open circuit in wire harness.
• Malfunction in throttle body.
• Malfunction in throttle cables.
• ISC valve is stuck fully open due to discon-
nected ISC unit hose or coupler. (High en- gine idle speed is detected with the ISC valve stuck fully open even though signals for the valve to close are continuously being transmitted by the ECU.)
• Malfunction in ECU.
• ECU fuse is blown."

--Open circuit in wiring harness is why I brought it to dealer; thought their diagnostics might have been able to identify something like that.
--Throttle bodies...I'm going to look closer at the boots that connect it and see if anything looks awry.
-- throttle cables seem to be fine and play is in spec (I did this early on and dealer confirmed)
-- ISC hoses are good/connected well.
-- malfunction in ECU always a possibility but I've gone through so many I think it's the reverse (bike causing ECU to malfunction)
-- ECU fuse is good, tested fuse connections at fuse block and the read 12+

Ref PM, thanks again.

// Radar //