2005 F225 problem

[fairdeal]

I am sure someplace near you has a competent tech.
the TPS values are way off.
some circuits actually share the same 5V reference.
lose the correct ref voltage and guess what the ECU see's for a sensors return voltage?

aha!

like when the optional water pressure sensor leaks into the harness

[Nautical]

TPS is off per Rod... Recalibrate the TPS and check MAP sensor with a vacuum pump if possible.

[rodbolt17]

I did NOT say recalibrate jack squat.
I did mention that the feed back voltage the ECU is seeing is off.
why its off is what a techs job is.

remember that ECU only reacts to what it "sees".
if it sees a voltage that is in its mapped range it reacts.
good or bad but it simply reacts to its mapping.

[Nautical]

[QUOTE=rodbolt17;114976]I did NOT say recalibrate jack squat.




and...nobody said YOU did.. It was meant as a reference to your previous comment on TPS value and my subsequent comment I made to recalibrate to start off ?? but I think its an intake leak ...

[rodbolt17]

an intake air leak will cause a high idle.
can also cause an intake backfire.
first you need to check the TPS ref voltage,then you can do the link and sync.
it does require a multi channel manometer.
at key on both the baro and intake pressure should be the same.

any backfire can spike the baro and intake pressure and cause that code.

lean back fire can also be caused by a clogged injector or low fuel pressure.

but none of my F225 manuals for the F225 D model show code 37 being utilized by the ecu.
on the 05 (D) model codes 33-44 are used for micro processor information not trouble shooting.

[boscoe99]

an intake air leak will cause a high idle.
can also cause an intake backfire.
first you need to check the TPS ref voltage,then you can do the link and sync.
it does require a multi channel manometer.
at key on both the baro and intake pressure should be the same.

any backfire can spike the baro and intake pressure and cause that code.

lean back fire can also be caused by a clogged injector or low fuel pressure.

but none of my F225 manuals for the F225 D model show code 37 being utilized by the ecu.
on the 05 (D) model codes 33-44 are used for micro processor information not trouble shooting.

What manual are you looking at? Only ones that I can find are LIT-18616-02-36 for the F225A model (2002) and LIT-18616-02-76s for the F225B (2003) and later year models. Both show code 37 as being related to an "incorrect idle speed control signal". In fact, the reference to code 37 in my post #4 is from LIT-18616-02-76.

[Nautical]

ISC Valve maybe acting up??

[rodbolt17]

Yamaha used the code 37, not ALL Yamaha ECU's used the code.

once again.
the ISC is NOT monitored by the ECU,PERIOD.
you can toss it in the creek and start the motor and NO ISC code could be generated.
would idle about 1500 but otherwise NOTHING.
look at the 1984-2005 tune up spec guide.
LIT-18559-84-05.

that guide will tell you everything you need to know about testing components on the 05 F225.

[boscoe99]

I don't know what to think any more. F225TXR SM's reference a code 37. The OP reports a code 37 being shown in YDIS. The tune up spec book does not show a code 37.

But then there is Yamaha data that specifically addressed the F225A, when it was new introduced, as having a code 37. Strange. Just strange.

[rodbolt17]

trust me, I know what the BOOK says.
I also know how it actually works.

nothing on the ECU monitors the ISC valve.
the % you see on YDIS,in this case the OP is using MEDS, is simply a percent opening REQUEST.

the ECU has no clue if the ISC is actually there or not.
the only thing one can deduce from a code 37 is the ECU is having issues making the engine idle at the correct speed for the paremeters in its map.

remember the ECU monitors various sensor feed backs and uses that data to set ign timing,fuel injector on time and the ISC position to control idle speed.

it does NOT monitor or "know" any physical issues.
air leaks,incorrect throttle shutters,incorrect fuel pressures , clogged injector filters,incorrect injector spray patterns such stuff as that is what bites folks.

the ISC valve has 12V + applied to the stepper motor windings anytime the key is on.
the ECU simply toggles a ground path to open or close the valve.
it will continue toggling until the target idle speed is reached.
its also why a stuck valve can take out an ECU and burn ign coils.
it will literally melt them.

if you don't belive me then simply unplug the ISC while the engine is running and see what happens.

[boscoe99]

It is fully understood that the ECU does not receive any output from the ISC valve. The ISC valve is a listener only. It only receives input from the ECU. It does not convey any information back to the ECU.

No one is doubting what you are saying about the ISC valve.

But then a code #37 may not be addressing the ISC valve. I don't believe so anyway.

For all I know the ECU is monitoring itself when it comes to the ECU output to the valve. Maybe the code is being set because the ECU is sending incorrect information to the valve. That is, the ECU knows what it supposed to be sending, knows that what it is sending is wrong, and therefore sets the code.

If it is sending bad information, and erratically at that, the ISC valve may be reacting to that bad information (valve opens and closes) and in so doing causes an erratic idle RPM.

So where to go from here? Verify TPS input voltage? Set the TPS to the correct output? Synchronize the throttle valves? Use YDIS to lock the ISC valve at a set position and then see if the idle RPM stabilizes. Which might indicate there are no intake manifold leaks?

Clear all codes and then see if code #37 shows up again and/or if the idle RPM becomes erratic again?

[boscoe99]

the ISC valve has 12V + applied to the stepper motor windings anytime the key is on.
the ECU simply toggles a ground path to open or close the valve.
it will continue toggling until the target idle speed is reached.
its also why a stuck valve can take out an ECU and burn ign coils.
it will literally melt them.

As you say, a ground is applied by the ECU to move the ISC valve in one direction or the other.

Once the valve is in a given position does the ECU disconnect the ground?

Reading up on stepper motors in general, some continue to apply a ground which results in current flowing through them at all times, without damage to the ECU. Seems that a Yamaha ECU cannot withstand continuous current flow to the valve actuator whereas other brands of stuff can.

I am aware of a bad ISC valve harming an ECU but have never understood exactly what is causing the failure.

Woe be unto he who simply replaces a failed ECU without first having verified the reason for the failure.

And shame on Yamaha for having a design wherein a lesser critical part (ISC valve) failing can damage a more critical part. This is verboten in aviation.

[rodbolt17]

may need to reread.
on the single and dual speed steppers if you DO NOT remove the ground the motor simply continues to run and either fully opens or fully closes the valve.

that valve isn't ment for 100% duty cycle.
it simply makes minor corrections,typically less than 2-3 percent.
means it is not used much.
however if the valve is stuck mechanically the ECU will keep toggling the ground in the attempt to make the idle stable and a speed that is mapped.
eventually this can lead to an ECU overcurrent(heat) and make the ECU go brain stupid and apply the ground for the ign coils causing them to melt not only the coil but the coil holding plate.

typically that valve on the 05F225 will run in the upper 50% to the mid 60% request range.
it physically cant make 0%.
if the ECU is requesting a 0% its cause either the manifold is leaking badly,a hose got left off the ECU is overheating or the mechanical position of the shutters are wrong and allowing to much air.

the ECU is rather stupid.
it assumes quite a bit.
it assumes the fuel rail pressure is correct.
it assumes the injector filters are clean.
it assumes the shutters are properly synced with a multichannel manometer and are not physically sticking.
the ECU is going to look at barometric pressure at key on,this gives an indication of air density.
the ECU is going to look at intake air pressure,this is an indication of engine load.
the ECU is going to look at coolent temp.
the ECU is going to look at air temp.
the ECU is going to look if it is in or out of gear.
the ECU is going to look at the TPS feedback(throttle angle).
the ECU is going to look at engine RPM.

now all the sensors are feeding the ECU,the ECU compares all the data and sets the ISC,ign timing and fuel injector on time to make the engine idle at its mapped point.
if it wont it can add a bit of timing,add a bit of air(ISC) add a bit of fuel,it can also take away the last 3 if needed.

its why you will never make an EFI motor idle rock solid like an old ultra high compression 425 oldsmobile at 450 RPM in drive.
EFI at idle constantly hunts,it overshoots then undershoots.
you can watch it on the laptop.
then when you see code 25 explain that one.
the last thing I would suspect is a faulty ECU.