2006 F90TLR Idle Problem

[lemay005]

Thanks.

I have not checked for, or touched any screws related to linkage adjustments. Not familiar with them, and nobody has been in this motor but me. However, early on while on the water, i couldn't get the boat into neutral while approaching the dock. I panicked a little and forced it into neutral to avoid hitting the dock -- could that have tweaked some linkage?

Leak down test? Nope -- never done anything like that, but I will get with my auto-mechanic buddy and see if he can help me do this -- I believe you laid down the procedure above. I'll review you post above and try to get the numbers back to this blog. It will be a couple weeks though as i'm going out of town.

What do most sensors have in common?.... I believe you're leading me to either the ECM or the wiring harness. My thoughts:
- The ECM seems to be functioning well based on the fact that the active monitoring is demonstrating performance with the YDS.
- The wiring harness? ...Maybe there is a bum sensor a broken/corroded ground wire that is messing with reference voltages, as you said earlier. Or maybe.

Another thought -- maybe dirt in the throttle body affecting the map reading?

[lemay005]

One thing i can do this weekend is clean the throttle body. THen i'll have to wait for a week or so to get together with my buddy to do leakdown...

Can you recommend a product for the throttlebody?

[rodbolt17]

could be a dirty throttle bore, your looking at it not me.
most all the sensors on that motor share a 5V ref and a common ground.
just because the ECU tossed a code does NOT mean the sensor is bad.
just means the ECU saw that feed back voltage out of its mapped range.
your MAP pressure running is about 26"Hg , a bit high for idle vacuum.
most 4 strokes typically idle at about 18-21"Hg or about 12"Hg for pressure.
MAP pressure and manifold vacuum can be looked at as the inverse of each other.

in other words.
at idle your motor should have about 20"Hg intake vacuum.
as the throttle is opened to WOT intake VACUM will go to about 0"Hg.

Manifold Absolute Pressure, at idle it will be about 12" Hg and as the throttle opens will go to about atmospheric pressure,typically about 30-32"Hg.

so two things stick out, 1 is your TPS voltage is almost off,two your intake air pressure numbers are off.
3 is the idle speed is way low.
the ISC is opening a bit more than normal in an attempt to make it run.
its also why the ign timing is a tad higher than normal and the injector on time is a bit high.

[boscoe99]

Would be nice if the word "vacuum" had never been invented/used.

I wonder why we do not use just one temperature setting as a standard and then call anything above that temperature in degrees but if it is below that temperature we call it something else. Would make about as much sense.

[rodbolt17]

cause back in the day it was engine vacuum,when EFI arrived with barometric pressure and intake pressure sensors it switched to MAP.
for years and years checking intake vacuum was a routine part of a tune up as it could spot all sorts of engine/valvetrain issues.
the MAP sensor readings on the laptop can now.
you just have to know what the readings mean.

and remember,just cause the laptop says the ISC is at 80% does NOT mean the valve actually moved.
its simply a requested value.
at 80% you should hear the air rusing past and the idle speed should be approaching 1000 RPM.
use the dynamic test function to test the ISC when running.

[lemay005]

Thanks for the replies! I've read back through everything and did the following today:

Read back thru my Seloc manual. It say at idle my tps should stay between0.8 and 1.2 and I reverified the ref voltage at 5.01vdc and plugged in YDIS to check again and I'm in that range.

Shut it off and listened for the isc to position itself for next start. Heard nothing. Turned key on, heard nothing. Went to static test and commanded the isc to cycle and heard it grumble.

Then pulled the isc and tried to blow through it (w/my finger over the other port). It was completely closed. So I blew through it while the static test ran and verified that it opened and it did. Then at the end of the test it completely closed again. Cycled the test again and this time it stayed open at the end of the three second test. Weird.

So now that I knew it was open some degree, I reinstalled it and the motor started without additional throttle help. Stayed at about 700-800 for a few seconds, then settled back down to a very low 475.

So I ran the active test to cycle the isc to 100%. I listened and put my finger on the valve and nothing happen. No increase in Rpm, and no sensation touching the isc.

When I shut it down and went back to the static test, it wouldn't work either. I played with the wires and disconnected the plug and reconnected. Then the test started to work and I could hear the isc move.

I'll check all four wires from the ECM to the isc and see if they beep good. I don't think the isc is dialed in with the ECM...

This isc is brand new. I destroyed the old leaning how it worked. (expensive lesson)

How does the ECM know the state or starting position of the isc? Does it drive the isc down past a limit so it knows it's completely closed and then pulse the stepper motor back up to a known position? I can't find anything that tells me what kind of signals to look for on the isc plug.

More confused than ever...

[lemay005]

ALL STOP!!

I've got two broken wires about an inch up from the isc. Pins 1 and 3 at the isc, which corresponds to 49 and 50 on the ECM...

Don't know what those signals are but they're definitely not connected! I'm goin to go jumper them and see what happens...

[lemay005]

Well, I jumpered the two wires.....

And I'm drinking a beer!!!!

Runs like she used too! Idle is up around 750 and I can't make her stall.

I took a snapshot with the YDIS. I'll upload the numbers later for comparison!

Very happy! Thanks for all your help. You really got my wheel turnin and I learned quite a bit!

[boscoe99]

There is a known issue with the cowling on early F90 EFI models snagging the ISC wires and breaking them over time.

Started life as a 6D8-82590-00-00. Later configuration is 6D8-82590-30-00.

The -30 denotes more than just a minor configuration change.

Funny that those that tried to take better care of their motors by removing the cowling more often for inspection/maintenance were more at risk of damaging the wire harness than were those that don't care and hardly ever remove their cowl.

Glad you found and solved your problem.

[rodbolt17]

like I have stated for what seems to be a half a million times.

that % number you see is simply an ECU request.
the ECU does not and cannot physically monitor the actual movement.
there are NO codes nor defaults for the ISC.
if you unplug it the engine may or may not run but the ECU wont know it.

same as fuel rail pressure, the ECU assumes its correct.
if the poster will now look at his ISC he will most likely see a request in the low 60% range.
what the ECU saw was a low idle and kept upping the request in order to raise and stabilize RPM based on the TPS and MAP and CPS and engine temp sensors.

now unplug on of those and the ECU reacts,ign timing defaults idle speed increases and a code is set.