CB1100 Idle speed instability problem

[Speed_imp]

Yesterday I removed my old IACV looking for coil wiring, magnet or mechanical fault. The housing and the spool of the valve do not show evidence of wear nor any kind of marks




I tried heating up the valve (sorry but I don't have the heat gun at home) to check coil resistance when hot. Resistance went up to over 120 Ohm, both coils the same. At the moment of the measure the valve was fuc..ng hot.



The spool of the valve its threaded or bolted on to the rotating axle. When the axle rotates the spool expands or retracts by action of the thread. It is not "one piece", the thread part is mounted over a spring and if you force it both parts can slip in reference to the other, still difficult to say there might be an issue




I exploded the valve looking inside for metallic build ups and to see the architecture of it



The coil is clean inside with no metallic build ups



In order to chech the condition of the magnets in the rotor and the magnetic field intensity I did an induction test which I will show you later

Old IACV supplier reference



New supplier reference


After all the checks I have not found an evidence of failure. Always thought that one of the magnets in the rotor could be weaker than the others thus failing in one of the steps and tyhen not being able to keep on turning in the same direction again. I made and induction test where I could check the whole set of magnetic field intensity and coil wiring

https://youtu.be/WcO3KK_2LMA

As I said I have not found a fault anywhere, it makes me think of a mechanic failure probably in the spool of the valve, I has two separate bodies joined by a spring and you can turn one in respect with the other if you slightly force it, where the system could loose the real position of the valve and giving a mistaken fuel mixture after that. I want to emphasize that my issue was LOW IDLE, never had high idle issues

[max]

That is quite an accomplishment speed, thanks a lot for the pictures.
I have always wondered what the iacv looked like inside, you can see the poles inside and the offset of the two coils to produce the different step positions, these steps are very small indeed, can you measure if the rotor has more than two poles with another magnet?

It will be interesting to see the outcome of Pawel's tesrting, you guys have contributed a lot of information!

So it does not look like something is out of alignment by the absence of any scratches, we have never seen any.

What i did notice is that the mounting plate with the two screws only fits correctly one way, when it captures and locks the notch in place and that was correctly mounted in your very first picture labelled "progress so far" so no factory mistake there.

Oh and please don't throw any bits away, we may need to look at them a little closer after the thinking has focused some, how's the moustache? took me a while to figure that one out

[syncronizator_imp]

That is quite an accomplishment speed, thanks a lot for the pictures.
I have always wondered what the iacv looked like inside, you can see the poles inside and the offset of the two coils to produce the different step positions, these steps are very small indeed, can you measure if the rotor has more than two poles with another magnet?

It will be interesting to see the outcome of Pawel's tesrting, you guys have contributed a lot of information!

So it does not look like something is out of alignment by the absence of any scratches, we have never seen any.

What i did notice is that the mounting plate with the two screws only fits correctly one way, when it captures and locks the notch in place and that was correctly mounted in your very first picture labelled "progress so far" so no factory mistake there.

Oh and please don't throw any bits away, we may need to look at them a little closer after the thinking has focused some, how's the moustache? took me a while to figure that one out

Hi MAX,
Hi Speed,
Hi all,

My video is here:
https://youtu.be/Qys_LsYXhWQ

Speed was it a play between spule and chamber ?
Was is a lot of space or was it tight?

[Speed_imp]

The housing of the valve is quite deep inside and difficult to check. I tried to check the clearance but I couldn't have a very good feedback so I couldn't say. I have started the engine, did the warm up, severeal times from 1st gear to neutral and the idle speed is very stable. Before the replacement it was quite easy to make it fail. First test looks ok, but still have to do some test ride to confirm the issue has dissapeared. The thing is that I couldn't do any check or diagnostic procedure that could point to a failure of any component. It could point to a mechanic failure of the IACV as some members have been stating.

PD: I have made 8 kilometers with start stop driving and everrything OK. By the way, I can not access the spreadsheet, why? I requested access but no answer yet.

That is quite an accomplishment speed, thanks a lot for the pictures.
I have always wondered what the iacv looked like inside, you can see the poles inside and the offset of the two coils to produce the different step positions, these steps are very small indeed, can you measure if the rotor has more than two poles with another magnet?

It will be interesting to see the outcome of Pawel's tesrting, you guys have contributed a lot of information!

So it does not look like something is out of alignment by the absence of any scratches, we have never seen any.

What i did notice is that the mounting plate with the two screws only fits correctly one way, when it captures and locks the notch in place and that was correctly mounted in your very first picture labelled "progress so far" so no factory mistake there.

Oh and please don't throw any bits away, we may need to look at them a little closer after the thinking has focused some, how's the moustache? took me a while to figure that one out

Hi MAX,
Hi Speed,
Hi all,

My video is here:
https://youtu.be/Qys_LsYXhWQ

Speed was it a play between spule and chamber ?
Was is a lot of space or was it tight?

Hi MAX,
Hi Speed,
Hi all,

My video is here:
https://youtu.be/Qys_LsYXhWQ

Speed was it a play between spule and chamber ?
Was is a lot of space or was it tight?
That video is clue. It makes sense that after giving throttle my idle speed is very low (valve closes) and little by little it goes to normal (opens step by step) if it does not stall before. Unfortunately still I don't know what is the problem, if this is the normal behaviour of the IACV engine speed should lower after giving throttle... Now I am really lost... I don't understand anything.

[Lord Popgun]

Speed,

Very interesting and informative pictures. I hope you don’t mind but I copied all of them in case they disappear in the future.

I hope your problem is now resolved and you can enjoy your motorcycle!

[max]

Pawel thanks for the video, it demonstrates things we have never seen before and is very helpful.

There is some abnormal behaviour with the iacv connected outside the engine,
because the engine is cold at startup the ecu controls the iacv to;

1 retract enough to know it's at the end of the stroke, after that it knows where the iacv is.
2 the ecu then extends about half that amount of steps which is programmed to get the engine to idle at 1500 rpm.
3 the ecu then tries to maintain 1500 rpm by trimming the iacv in or out depending, it chases a set point.
4 as the engine warms up it reduces the rpm's to a programmed " map " of target rpm's until it reaches 1050 rpm.

Like Speed i was expecting the iacv to retract on opening the throttle rather than close it, maybe they programmed it so the throttle is less snatchy or makes the mixture richer, who knows.
But thanks to your video's we now know a lot more about the iacv behaviour, all we have to do is understand it's role in the throttle body.

Pawel if possible at some stage could you do the same thing but with an indicator on the shaft like the copper wire?
Also looking at it sideways makes it difficult to see which way it is moving, something like a piece of electrical tape like a flag would do it with a 45 degree view of it.

Two things i noticed;
1 the pin in Speed's picture seems to protrude ( stick out ) more than seems necessary to guide the piston and;
2 Pawel's piston appears to have a wear mark inside the groove on the bottom at the iacv end.

This is probably not important since the fault went away by replacing the iacv but it just struck me as a bit suspicious.

From what i understand the software inside the ecu was changed in 2014, does this have to do with it and; why is it only happening to a few bikes?

Here is a video clip from "zam's channel" (dl2zam for us hams) in Germany where he removes the iacv housing from a similar throttle body like ours that may help to understand what's going on inside our engines;
https://www.youtube.com/watch?v=_asKPXxu...e=youtu.be

His video's are usually an hour or so long so i picked out what could be helpful for us and no, there is no access from the top, the fuel injection is in the way, i tried.

Followed a lot of his very interesting but technical video's.

[syncronizator_imp]

Pawel thanks for the video, it demonstrates things we have never seen before and is very helpful.

There is some abnormal behaviour with the iacv connected outside the engine,
because the engine is cold at startup the ecu controls the iacv to;

1 retract enough to know it's at the end of the stroke, after that it knows where the iacv is.
2 the ecu then extends about half that amount of steps which is programmed to get the engine to idle at 1500 rpm.
3 the ecu then tries to maintain 1500 rpm by trimming the iacv in or out depending, it chases a set point.
4 as the engine warms up it reduces the rpm's to a programmed " map " of target rpm's until it reaches 1050 rpm.

Like Speed i was expecting the iacv to retract on opening the throttle rather than close it, maybe they programmed it so the throttle is less snatchy or makes the mixture richer, who knows.
But thanks to your video's we now know a lot more about the iacv behaviour, all we have to do is understand it's role in the throttle body.

Pawel if possible at some stage could you do the same thing but with an indicator on the shaft like the copper wire?
Also looking at it sideways makes it difficult to see which way it is moving, something like a piece of electrical tape like a flag would do it with a 45 degree view of it.

Two things i noticed;
1 the pin in Speed's picture seems to protrude ( stick out ) more than seems necessary to guide the piston and;
2 Pawel's piston appears to have a wear mark inside the groove on the bottom at the iacv end.

This is probably not important since the fault went away by replacing the iacv but it just struck me as a bit suspicious.

From what i understand the software inside the ecu was changed in 2014, does this have to do with it and; why is it only happening to a few bikes?

Here is a video clip from "zam's channel" (dl2zam for us hams) in Germany where he removes the iacv housing from a similar throttle body like ours that may help to understand what's going on inside our engines;
https://www.youtube.com/watch?v=_asKPXxu...e=youtu.be

His video's are usually an hour or so long so i picked out what could be helpful for us and no, there is no access from the top, the fuel injection is in the way, i tried.

Followed a lot of his very interesting but technical video's.

No problem MAX. Tomorrow morning the engine will be cold again.
I will repeat the test .. and will do a better video.

I would like to correct that what I felt touching the piston .. I said that it was gently stepping back.
When I put the copper wire on the shaft, you could see that it really was 2 moves. First to the right and second to the left.
In fact, the piston shifted forward and backward alternately.

Maybe a defective IACV series was produced and that series was used our in hondas 2014.
Maybe we should compare the VIN of everyone who has this problem.
Maybe we should compare the IACV series NR which is printed on the valve body.
Mine old IACV 31128A
Speed,s old 31012E

Did it also happen in 2015 and 2016?

My mechanic admitted, however, that there is some ECU re-flash procedure.
He said that this is done by unauthorized workshops ... e.g. to remove the speed limit.

I planned to go to Norway this summer through Denmark. There is a virus age now ... but ... if they open borders, I probably will.
Along the way there is the Honda service, which did the upgrade of Wisedum's bike.
In this situation, I would go there and ask to change the software version.
I can also go to the Honda Poland office (not dealers) which is near my working place.
Maybe I can talk to someone form Honda who will get the copy of new image and will forward it to Polish dealers.

I think that... much has been done in this case.
I don't know how many people have this problem right now.
I had a problem for a year ... I read this post and did nothing about it.
Finally, I decided to take the risk that the IACV replacement would change nothing.
Now I have driven 922km since the IACV exchange.
I fell in love with my again

Speed .... were you able to drive more kilometers after the IACV exchange?

[SportsterDoc]

Glad to read of your success today. Since this is a very long thread I will re-post the summary from Post 775, a couple years ago:

It does not seem to be a MAP issue, due to symptoms not matching.

It does not seem to be an EOT issue, per reports in this thread and symptoms not matching

It does not seem to be a TPS issue, due to the recent testing guided by Max. There may have been one or two TPS issues, but not for Dave.

Manual pages 5-74 and 5-75 cover IACV (symptoms seem to match): One check is to listen for the sound of it cycling with key on and stop/run on. There is a caution about cleaning before removal to prevent debris in the IACV passage...therefore, any debris would be a concern to proper operation.

Note the symptoms/fail safe function of all DTC on pages 5-15 and 5-16 of FSM.

In the b&w photo at the bottom of page 5-74, it is not sufficient quality to see any air ports to the sides of the passage. If IACV replaced, without cleaning, an IACV issue may remain.

The IACV is 16430-MJF-D01

The IACV can be tested, per the factory service manual:

IACV testing, per FSM 15-41 & 15-42:

Note: These tests may be done with IACV mounted, by lifting rear of fuel tank and removing right side throttle body cover.

1. After clearing stored DTC, per page 5-14, recheck for stored DTC 29-1. If none, then prior DTC was intermittent.

2. Measure resistance of each of the four wires at the ICAV connector (disconnected, harness side, not IACV side). Continuity to ground should be infinity. If not, the wiring harness has a short to ground.

3. Check continuity to ECM, from disconnected ECM 33 pin to disconnected IACV 4 pin connector
Positions are numbered with locking tab up:

ECM A6 black/yellow to IACV connector postion 1 (left)
A17 black/red, position 2
A16 black/blue, position 3
A7 black/orange, position 4 (right)

4. Measure IACV resistance, (IACV side, disconnected), facing with locking tab up at airbox side (mirror image of connector):
position 4 black/yellow (right)
position 3, black/red
postion 2, black/blue
position 1, black orange (left)
a. black/yellow to black orange (2 outside positions), 99-121 ohms at 77F/25C
b. black/red to black/blue (2 inside positions), 99-121 ohms at 77F/25C
If resistance out of spec, FSM declares IACV faulty

My 2 cents: If IACV and wiring tests good, then if symptoms continue to point to IACV, it may be a piston travel issue or air port issue.

Summary, to date:

Max started a very comprehensive thread on the IACV.

http://cb1100forum.com/forum/showthread.php?tid=12203

Post 9, Feb 19:

vacuum loss (minor = high idle, major = close to stalling/stalling)
TPS (FSM symptom/fail safe: hard to start cold)
IACV (FSM symptom/fail safe: engine stalls, hard to start, rough idle
EOT (FSM symptom/fail safe: poor acceleration)

DTC 29-1, FSM page 5-16, lists IACV circuit malfunction as "loose or poor contact of IACV connector, IACV or its circuit malfunction".

Otherwise, per the FSM, other sensors failsafe is normal engine operation, this includes MAP, IAT and O2. There is no mass flow sensor or exhaust temp sensor on the CB1100.

The FSM incudes all sensors on pages 5-15 and 5-16.

Symptoms reported are classic for IACV.

The piston not moving as much as the stepper steps would not likely provide a DTC (opinion) and this may be more likely than any other aspect of the IACV operation.

Post 11:

Just glancing at pages 5-15 and 5-16 shows how well the CB1100 will continue to perform with many sensor codes.

If the EOT is wonky, the only issue is hard starting cold.

If the IAT is wonky, default is 95 F.

If TPS is wonky, default is 0 degrees position

If an O2 sensor is wonky, "engine operates normally"

However, if a fuel injector faults, it is time to push: Engine does not start, injector power, pump and ignition shut down in the event of "loose or poor contact of the fuel injector connector-fuel injector or its circuit malfunction"...fail-safe is not just complete failure...it is out of spec parameters.

Post 16:

The "advantage" of purchasing the entire throttle body assembly is that the IACV port would be clean, not warped, with new IACV and new TPS.

...hearing the IACV cycling indicates that the stepper motor is stepping or trying to step. If crud is preventing full operation, it may not sound much different. The ECM has no feed-back regarding actual movement.

[Speed_imp]

Pawel thanks for the video, it demonstrates things we have never seen before and is very helpful.

There is some abnormal behaviour with the iacv connected outside the engine,
because the engine is cold at startup the ecu controls the iacv to;

1 retract enough to know it's at the end of the stroke, after that it knows where the iacv is.
2 the ecu then extends about half that amount of steps which is programmed to get the engine to idle at 1500 rpm.
3 the ecu then tries to maintain 1500 rpm by trimming the iacv in or out depending, it chases a set point.
4 as the engine warms up it reduces the rpm's to a programmed " map " of target rpm's until it reaches 1050 rpm.

Like Speed i was expecting the iacv to retract on opening the throttle rather than close it, maybe they programmed it so the throttle is less snatchy or makes the mixture richer, who knows.
But thanks to your video's we now know a lot more about the iacv behaviour, all we have to do is understand it's role in the throttle body.

Pawel if possible at some stage could you do the same thing but with an indicator on the shaft like the copper wire?
Also looking at it sideways makes it difficult to see which way it is moving, something like a piece of electrical tape like a flag would do it with a 45 degree view of it.

Two things i noticed;
1 the pin in Speed's picture seems to protrude ( stick out ) more than seems necessary to guide the piston and;
2 Pawel's piston appears to have a wear mark inside the groove on the bottom at the iacv end.

This is probably not important since the fault went away by replacing the iacv but it just struck me as a bit suspicious.

From what i understand the software inside the ecu was changed in 2014, does this have to do with it and; why is it only happening to a few bikes?

Here is a video clip from "zam's channel" (dl2zam for us hams) in Germany where he removes the iacv housing from a similar throttle body like ours that may help to understand what's going on inside our engines;
https://www.youtube.com/watch?v=_asKPXxu...e=youtu.be

His video's are usually an hour or so long so i picked out what could be helpful for us and no, there is no access from the top, the fuel injection is in the way, i tried.

Followed a lot of his very interesting but technical video's.

No problem MAX. Tomorrow morning the engine will be cold again.
I will repeat the test .. and will do a better video.

I would like to correct that what I felt touching the piston .. I said that it was gently stepping back.
When I put the copper wire on the shaft, you could see that it really was 2 moves. First to the right and second to the left.
In fact, the piston shifted forward and backward alternately.

Maybe a defective IACV series was produced and that series was used our in hondas 2014.
Maybe we should compare the VIN of everyone who has this problem.
Maybe we should compare the IACV series NR which is printed on the valve body.
Mine old IACV 31128A
Speed,s old 31012E

Did it also happen in 2015 and 2016?

My mechanic admitted, however, that there is some ECU re-flash procedure.
He said that this is done by unauthorized workshops ... e.g. to remove the speed limit.

I planned to go to Norway this summer through Denmark. There is a virus age now ... but ... if they open borders, I probably will.
Along the way there is the Honda service, which did the upgrade of Wisedum's bike.
In this situation, I would go there and ask to change the software version.
I can also go to the Honda Poland office (not dealers) which is near my working place.
Maybe I can talk to someone form Honda who will get the copy of new image and will forward it to Polish dealers.

I think that... much has been done in this case.
I don't know how many people have this problem right now.
I had a problem for a year ... I read this post and did nothing about it.
Finally, I decided to take the risk that the IACV replacement would change nothing.
Now I have driven 922km since the IACV exchange.
I fell in love with my again

Speed .... were you able to drive more kilometers after the IACV exchange?

Only made about 8 Km with start stop driving and the fault did not reproduce. I have to test drive more kilometers. Tomorrow won't rain and I expect to drive more to confirm the repair.

[syncronizator_imp]

MAX , the video is ready:

https://youtu.be/HWZftoKg86U