2006 F90TLR Idle Problem

[lemay005]

Hi - I'm new and need help.

My original symptom was the motor ran great when cold and I could go all day at 4500 rpms; but, when I came back to the dock it would idle erratically and stall. sometimes it would start right back up and idle normally and sometimes the erratic idle would persist.

so far I have replaced the thermostat (tested it in a pan of hot water -- it was bad) and I replaced the ISC valve after some serious consideration. Problem persists.

Then....I went and bought the YDIS cable and software. So now, the motor will start with the muffs on but it won't idle right. I have to give it a little throttle to get it to start and after it warms up, it won't maintain idle above 525 or so.... before this problem started, it would start and the idle would jump up to around 900-1000, then quickly settle down to around 600-700 when cold.

None of the sensors are indicating anything out of range on the YDIS diagnostic -- but it just won't idle right.

Is there some sort of setup that I need to do? One mechanic briefly said, "...you might just need to do a link and sync..." But I don't know what that is and it's not in my SELOC manual. I assumed he was talking about syncing carbs, which I don't have -- I'm EFI...

Thoughts?....

thanks -- Eric

[rodbolt17]

if no codes are thrown it narrows down trouble shooting.
means you don't have to chase ghosts or peter cottontail it.
means now we are looking at what could cause either the ISC to not react OR what could cause the ECU to react.
what is the only electronic device NOT monitored by the ECU?????
its the ISC valve.
unplug it and the engine may or may not run but the ECU never knows it.

typically after running the engine and you turn the key off you will hear the ISC rattle as it resets to the 100% open position in anticipation of the next restart.

do you hear it?

with YDS you can play with the ISC position both running,dynamic test, or key on engine off,static test.
word: if you hold it in your hand and run the static test keep light finger pressure on the pintle.

now what OTHER function is monitored but has such a wide feedback range as to be stupid???????

baro AND map pressure.
at key on your baro pressure should agree with your local weather channel.
if its stupidly high or stupidly low start checking pins in the harness for that 3 wire circuit.
remember the 5V ref for the map sensor can be loaded down by another sensor.

mechanically the ECU cant monitor rail pressure nor cyl sealing ability.
a leak down test can tell you IF the cylinders can seal.
DO NOT use a compression test as it can be misleading and is a teat on a boar hog at best.

rail pressure can be monitored with a simple test guage.

I recently finished an F80, compression numbers that another tech wrote on the cam cover.#1 142,#2 145,#3 140#4 135.
would you accept those compression numbers ?

[greasyshaft]

if no codes are thrown it narrows down trouble shooting.
means you don't have to chase ghosts or peter cottontail it.
means now we are looking at what could cause either the ISC to not react OR what could cause the ECU to react.
what is the only electronic device NOT monitored by the ECU?????
its the ISC valve.
unplug it and the engine may or may not run but the ECU never knows it.

typically after running the engine and you turn the key off you will hear the ISC rattle as it resets to the 100% open position in anticipation of the next restart.

do you hear it?

with YDS you can play with the ISC position both running,dynamic test, or key on engine off,static test.
word: if you hold it in your hand and run the static test keep light finger pressure on the pintle.

now what OTHER function is monitored but has such a wide feedback range as to be stupid???????

baro AND map pressure.
at key on your baro pressure should agree with your local weather channel.
if its stupidly high or stupidly low start checking pins in the harness for that 3 wire circuit.
remember the 5V ref for the map sensor can be loaded down by another sensor.

mechanically the ECU cant monitor rail pressure nor cyl sealing ability.
a leak down test can tell you IF the cylinders can seal.
DO NOT use a compression test as it can be misleading and is a teat on a boar hog at best.

rail pressure can be monitored with a simple test guage.

I recently finished an F80, compression numbers that another tech wrote on the cam cover.#1 142,#2 145,#3 140#4 135.
would you accept those compression numbers ?

Haha did he even open the throttle? see this so often

[lemay005]

Thanks much for the replies. I'm trying to attach an excel file with the YDS printout. I have two captures in the same file -- one with the engine off and one with it idling at temp. See what you think -- i notice that an air intake temp diagnosis popped up.

Thoughts?

[rodbolt17]

I will ask again, would you accept those compression numbers?

[boscoe99]

I will ask again, would you accept those compression numbers?

If the motor starts, idles and runs well what would be the basis for rejecting the motor based on those pressures?

Minimum compression pressure specification published by Yamaha for an F70 (closest comparable motor) is 116 psi.

F70 has a compression ratio of to 9.4 to 1 whereas the F80 compression ratio is 9.6 to 1.

Yamaha Japan does not list a specification for a differential pressure test, aka leak down, in the service manual.

A differential pressure test only indicates pressure held by the cylinder with the piston at top dead center. What if a cylinder wall is scored below the upper most point of the piston ring travel? How does a differential pressure test indicate that?

[rodbolt17]

a COMPRESSION test on a four stroke outboard is A TEAT ON A BOAR HOG AT BEST.

maybe yor neighbors tom cat can suckle kittens.
dunno

but a compression test on a Yamaha 4 stroke is about as useful as teats on a boar hog.

[greasyshaft]

I usauly just stick my thumb over the spark plug hole and get a feel for the pressure before moving onto the next cylinder.

[boscoe99]

a COMPRESSION test on a four stroke outboard is A TEAT ON A BOAR HOG AT BEST.
.

Tell us why please.

Being that it is a dynamic test, and therefore more closely mimics the operation of a cylinder, as opposed to a differential pressure test, which only tests sealing of a cylinder at one specific point, many mechanics feel that it is a very useful tool.

A compression test may tell if there is a problem. A differential pressure test may tell where problem is.

Do you simply not do a compression test and only do the more time consuming and thus costly differential pressure test?

Have you given any thought to the use of the same differential pressure check device being used on an F2.5 and an F350? Should leakage from the smaller motor be to the same limits as the bigger motor?

[rodbolt17]

leakage is leakage.
from the mighty f2.5 to the F350 the limit is 15%.
the above posted numbers were actual numbers a tech did on an F80 I recently had to repair.
while the numbers LOOKED ok the problem was a corroded spot in #4 cyl allowing water into the cyl.
the LEAK down rate was 45% on that cyl and air blowing out of the tell tale.
I can do 3 leakdown tests before you finnish the first compression test.

v6 F225 compression test.
insert tester,crank engine at least 5 revolutions,remove tester,repeat.

F225 V6 leakdown test.
rotate flywheel to #1 TDC,do the test,rotate flywheel bringing up #2 TDC,then 3 then 4 then 5 then 6 and I am done.
I have not stepped away from the engine.
on the F150 it would be 1,3,4 and 2,done.
the V8 is a pain as the flywheel has no index marks.
once you find #1 tdc then you count the flywheel teeth, do a bit of math and mark the flywheel to find TDC on the rest.

but this is why a compression test on a fourstroke outboard is a teat on a boar hog.
the numbers can look acceptable yet the motor is still broke.
by the time flagship marine welded and surfaced the head,did the valve job and I was done with the carbs the bill was about 2400 bucks.
but 3 other techs had had a go at it and all 3 did a compression test and passed the motor.

[boscoe99]

but this is why a compression test on a fourstroke outboard is a teat on a boar hog.
the numbers can look acceptable yet the motor is still broke.
by the time flagship marine welded and surfaced the head,did the valve job and I was done with the carbs the bill was about 2400 bucks.
but 3 other techs had had a go at it and all 3 did a compression test and passed the motor.

Well, obviously something was wrong with the motor. I presume it was not running correctly or it would not have gone from mechanic to mechanic to mechanic.

This sounds like a mechanic problem and not a test procedure problem.

Which is why I said if the motor runs well and compression checks good then in most cases a compression check is sufficient. Now if the motor is not running well, and the compression checks OK, then shame on the three mechanics for saying that it is OK based on a compression check only.

I have seen problematic motors that have damn near perfect results from a differential pressure check. It should tell the mechanic that further investigation is needed. Same as with the compression check.

Mechanics are sorely lacking in theory. Yamaha does not teach theory for the most part so maybe the mechanics don't think it is really necessary. So much more fun and lucrative for a shop to remove and replace parts.

[lemay005]

I wish I knew more about what you guys are talking about. I'm really a novice mechanic (i shouldn't even say mechanic...)

I get the concept of what you're saying about compression, but i really don't know anything about the performance impact of incorrect pressures or what those thresholds are.

I don't think my upload of the YDS report worked either. I'll try to embed it below. I can hear the ISC moving in the static test. But in the active test, it doesn't cause the rmps to increase when i command 100% open. And when i do the valve angle test, the valve angle would open as i increased throttle, then get to 60% and stay there. After the engine was warm, it would go to 80% and stay there. never saw 100%. So, I was focused on your first comment regarding the air pressure and saw the following.

This first on is with the engine NOT running.

Save date July 31 2014
ECM No.: 6D88591A11

Diagnosis
Code Item Result
13 Pulser coil Normal
15 Water temp sensor Normal
17 Knock sensor Normal
18 Throttle position sensor Normal
19 Battery voltage Normal
23 Intake temp sensor Normal
28 Shift position switch Normal
29 Intake press sensor Normal
37 Intake air passage Normal
44 Engine stop lanyard switch Off
49 Over cooling Normal

Diagnosis Record
Total hours of operation 322
Code Item Occurred
29 Intake press sensor 13.6
37 Intake air passage 303.7
28 Shift position switch 320.5

Engine Monitor
Monitor Item Result Unit
Engine speed 0 r/min
Intake pressure 101.61 kPa
Intake pressure 30.08 inHg
Atmospheric pressure 1016.1 hPa
Atmospheric pressure 30.1 inHg
Ignition timing - deg
Battery voltage (12-16) 12.1 V
TPS voltage (0.5-4.5) 1.193 V
Throttle valve opening (0-90) 12.3 deg
ISC valve opening 60 %
Fuel injection duration 0 ms
Water temperature (below 90) 31.6 °C
Water temperature (below 194) 88.9 °F
Intake temperature (below 70) 30.4 °C
Intake temperature (below 158) 86.7 °F
Engine stop lanyard switch OFF
Shift position switch ON
Oil press switch ON
Dual engine system switch OFF

THIS NEXT LIST IS AFTER WARM UP WITH ENGINE RUNNING:

Save date July 31 2014
ECM No.: 6D88591A11

Diagnosis
Code Item Result
13 Pulser coil Normal
15 Water temp sensor Normal
17 Knock sensor Normal
18 Throttle position sensor Normal
19 Battery voltage Normal
23 Intake temp sensor Normal
28 Shift position switch Normal
29 Intake press sensor Normal
37 Intake air passage Normal
44 Engine stop lanyard switch Off
49 Over cooling Normal

Diagnosis Record
Total hours of operation 322
Code Item Occurred
29 Intake press sensor 13.6
37 Intake air passage 303.7
28 Shift position switch 320.5
23 Intake temp sensor 322

Engine Monitor
Monitor Item Result Unit
Engine speed 523 r/min
Intake pressure 26.6 kPa
Intake pressure 8.15 inHg
Atmospheric pressure 1016.1 hPa
Atmospheric pressure 30.1 inHg
Ignition timing BTDC 3 deg
Battery voltage (12-16) 12.5 V
TPS voltage (0.5-4.5) 1.031 V
Throttle valve opening (0-90) 8.3 deg
ISC valve opening 80 %
Fuel injection duration 2.12 ms
Water temperature (below 90) 77.5 °C
Water temperature (below 194) 171.5 °F
Intake temperature (below 70) 32.4 °C
Intake temperature (below 158) 90.4 °F
Engine stop lanyard switch OFF
Shift position switch ON
Oil press switch OFF
Dual engine system switch OFF

[lemay005]

Note that after i started the engine, a new item popped up on the diagnosis list.

"Air Intake Temp" But looking at the values in the monitor, the temp only went up 4 degrees. Is it possible the the real sensor reading went completely out of range and the ECM just substituted a typical value of 90.4 deg F.?

Also i don't know how much pressure drop i should see with the engine running. In this case, i'm seeing it go from about 30 inHg down to 8 inHg. Is that normal?

[lemay005]

Also - I have printouts of the engine in the following running conditions if you want to see those:

RMP ~1000, Temp ~97 F.
RPM ~2500, Temp ~159 F.
RPM ~3300, Temp ~159 F.

[rodbolt17]

your TPS voltage is way off.
your running intake pressure is about 4"Hg lower than what I would expect to see.

have you checked for correct linkage adjustments?
has anyone dinked with the throttle shutter screw, that's NOT supposed to be dinked with yet folks do?
have you done a LEAK DOWN test.
this test, no matter what you read on the net, is the definitive test on can the cyl mechanically seal.
if they CANNOT then NO amount of screw dinking will help.
as posted above its possible to have very good compression numbers but a poor running motor due to lack of cyl sealing.
this CANNOT happen with a leakdown test.

typically on a compression test your looking for less than 10% difference highest to lowest.

on the F80 I was dissscussing the highest was about 145 so the lowest has to be at least about 130, it was.

however the water leaking into the cyl was affecting engine operation.

a leakdown test is simply faster and far more accurate on most all Yamaha fourstrokes.

on your 90, I would look at cyl sealing or an air leak or someone dinky danked with the screws.

I just did a 2 stroke 130 that the customer did the carbs himself.
it idled well but no power.
by the time I got it and fixed the power issue it took another 30 min to reset the linkage cause they had adjusted everything with a screw.

his issue was a frozen/corroded in place timer base.

moral of that story: if you don't KNOW what that screw does, leave it be.

on your sensor issue.
what do most ALL these sensors share in common?