CB1100 Idle speed instability problem

[max]

Gracias.

[Speed_imp]

Gracias.

De nada hermano!

[Speed_imp]

I recorded the signals to one same coil. Popgun recorded the signals to both coils. Looking at the videos I realised one thing:

- The valve has 4 wires and 2 coils. All 4 wires are "hot", they send 12 volt pulses
- 2 wires of a same coil send 12 volt pulses of 1/2 cycle long phasing them 1/2 cycle

In the image signals from both sides of same coil


- Both coils are phased between each other 1/4 of a cycle

In the image measuring one wire of coil A and one wire of coil B


- If we number the wires 1 - 2 - 3 - 4 (1 - 2 are coil A and 3 - 4 are coil B let's say) ECU sends the signals is this sequence

1-3-2-4 (complete cycle, 1/4 cycle between them)

In that sequence the valve turns one direction. If the ECU wants to turn it counterwise I suppose it just have to invert 2 wires in a similar way and induction electric motor inverts its rotating direction inverting 2 wires. So it will sequence the signaling this way

1-4-2-3 (complete cycle, 1/4 cycle between each pulse)

This could be checked with 2 probes. One probe connected to both ends of coil A and the other probe connected to both ends of coil B

Just wanted to share this thought with you.

[zirconxi_imp]

These are all too technical for me... In shorts, for iacv problem, any particular symptoms and easier check with common tools that can be perform by amateur like me in the future if it happen to my bike again?? So far, touch wood, my bike now run like normal after that single incident..

[syncronizator_imp]

Too bad, that a software update isn't allowed to fix the idle problem in the USA. Honda released it due to this problem and it totally cured this very annoying fault unexpensively for me without changing other parts of the bike, which more or less feels like fishing in the dark. The reason for a missfunction is to be seen in a not correct programming for the injection combined with the intake valves, a Honda dealer explained in my country after his treatment. This was that.

Wisedrum

Hi Wisedrum,
Here in Warszawa I am in contact with Honda Motorcycle service dealer.
The Manager of this Honda service is an owner of cb1100 and has 30 years experience as a motorcycle mechanic.
The owner of this Honda service also have CB1100.
I was asking them about ECU software upgrade.
They check especially for my request in honda docs ..which normally are not available for regular dealer.

They consulate it with main technologist from Honda Poland.
No one has ever heard in Poland about software upgrade.

Can You share contact to German service who did for You upgrade of the ECU software ?

What software version was in Your ECU before and what is now ?
Is the any official or unofficial honda document about it?
Can You call him and ask again for details?
The problem is so painful for so many people around the world.
I am in lucky situation that i can drive to Germany (when virus ends) ad go to the dealer for upgrade.
But where ?

Anyway i will later construct new post ... must do a few rides today to check and confirm if my problem is resolved or no.

I accidentally moved the IACV by turning it 1-2 degrees when I tried to remove the plug.
It all changed for good, though not perfectly.
The problem returned, but extremely rarely and on a smaller scale.

Paweł

[Speed_imp]

Quote:I accidentally moved the IACV by turning it 1-2 degrees when I tried to remove the plug.
It all changed for good, though not perfectly.
The problem returned, but extremely rarely and on a smaller scale.

Paweł
Could be a connector bad contact? Actually my IACV also has some free movement, rotates freely on it's own axle for a few degrees, maybe 2 degrees yes. I haven't experienced there is any improvement if moving it... I have to check that, doesn't look like a repair but maybe helps diagnosing it.

Too bad, that a software update isn't allowed to fix the idle problem in the USA. Honda released it due to this problem and it totally cured this very annoying fault unexpensively for me without changing other parts of the bike, which more or less feels like fishing in the dark. The reason for a missfunction is to be seen in a not correct programming for the injection combined with the intake valves, a Honda dealer explained in my country after his treatment. This was that.

Wisedrum

Hi Wisedrum,
Here in Warszawa I am in contact with Honda Motorcycle service dealer.
The Manager of this Honda service is an owner of cb1100 and has 30 years experience as a motorcycle mechanic.
The owner of this Honda service also have CB1100.
I was asking them about ECU software upgrade.
They check especially for my request in honda docs ..which normally are not available for regular dealer.

They consulate it with main technologist from Honda Poland.
No one has ever heard in Poland about software upgrade.

Can You share contact to German service who did for You upgrade of the ECU software ?

What software version was in Your ECU before and what is now ?
Is the any official or unofficial honda document about it?
Can You call him and ask again for details?
The problem is so painful for so many people around the world.
I am in lucky situation that i can drive to Germany (when virus ends) ad go to the dealer for upgrade.
But where ?

Anyway i will later construct new post ... must do a few rides today to check and confirm if my problem is resolved or no.

I accidentally moved the IACV by turning it 1-2 degrees when I tried to remove the plug.
It all changed for good, though not perfectly.
The problem returned, but extremely rarely and on a smaller scale.

Paweł

The dealer is Autohaus Aschkar, thet have a webpage with the email address. I tried to send them an e-mail but I don't know what I made with my mail account that is not sending or receiving messages (the master of informatics) since yesterday. So if you get in contact with them and try to get the service bulletin or the Software ID and share it would be very handy, so not everybody is calling them for the same issue and making them work for free .

[max]

Who else thinks it's an alignment problem, thanks Pavel.

Imagine looking at the iacv from the back;
During the time when the rev's are low, can you blip the throttle and move the iacv 1 "nose up", " nose down" left or right?
If it rights itself during one of these movements that would indicate a misalignment with the cylinder, there are two "o rings" holding the iacv in place, they may have enough flexibility to move just enough to clear the dragging spot.

Next thing is to maintain the new position of the iacv somehow.

Interesting observation Pavel.



Not our bike but here is what the iacv cylinder looks like, notice the pin inside the cylinder which runs in the groove of the piston which prevents the piston to rotate;


What if the bracket on the back of the iacv is slightly off measurement or positioned a bit in one direction?


It seems the piston gets "stuck" when it is extended furthest into the cylinder and restricts the idle air flow the most.


Speed the wiring does not change polarity in a reverse rotation but the micro controller decides to reverse the 90 degree timing step and flips 180 degrees, exactly like when you walk backwards and change the timing of your feet, one behind the other instead of in front, same thing

[Lord Popgun]

Max, I had suspicion of binding since right after we started all this. Especially after nothing was found bad, yet changing the IACV cured the problem

[SportsterDoc]

Who else thinks it's an alignment problem, thanks Pavel.

Imagine looking at the iacv from the back;
During the time when the rev's are low, can you blip the throttle and move the iacv 1 "nose up", " nose down" left or right?
If it rights itself during one of these movements that would indicate a misalignment with the cylinder, there are two "o rings" holding the iacv in place, they may have enough flexibility to move just enough to clear the dragging spot.

Next thing is to maintain the new position of the iacv somehow.

Interesting observation Pavel.



Not our bike but here is what the iacv cylinder looks like, notice the pin inside the cylinder which runs in the groove of the piston which prevents the piston to rotate;


What if the bracket on the back of the iacv is slightly off measurement or positioned a bit in one direction?


It seems the piston gets "stuck" when it is extended furthest into the cylinder and restricts the idle air flow the most.


Speed the wiring does not change polarity in a reverse rotation but the micro controller decides to reverse the 90 degree timing step and flips 180 degrees, exactly like when you walk backwards and change the timing of your feet, one behind the other instead of in front, same thing

Max
Concern for IACV piston binding was expressed in posts
846
833
775, as excerpted below:

(03-21-2018 07:25 AM)pdedse Wrote:
With this information does Dave now have "probable cause" that the IACV is the culprit?

Dave ordered a new IACV from his Honda dealer.
The part is backordered, so there may be a delay in receiving the part.
Dave emailed that he is loyal to his dealer and choose to not order on-line and his dealer gave him a price as good as/close to on-line.

A couple weeks ago (post 726) I commented: "Even though the IACV operation is a prime suspect in most of the reported idle issues, there may be (instead of or in addition to) poor electrical connection(s)."

This may have been Max's direction earlier than that, but Max wanted to be sure that all other possibilities were checked, since replacing the IACV will take more labor than the other checks.

The only other step which may be practical to do, waiting for the new part, would be to unbolt the IACV (air box in place), pull it back enough to squirt some silicone lubricant into the area, which may facilitate easier movement (or not?)...the theory being that if it is binding, the IACV may not in itself be defective, but not able to operate properly.

[syncronizator_imp]

My story is similar to anyone who has experienced this problem.
Idle speed drops to 500. Sometimes it increases to 1500.
I was struggling with this for 1 season, around 17000 km.
I didn't have a DTC that pointed to IACV.

Recently, idle was stayed at 1500 and did not want to fall down.

I have read the SM and forum.
I made all possible measurements with an ohmmeter and voltmeter.
Oil temperature sensor OK (EOT), its resistance is in accordance with the service manual, 2.7K ohms at 20 degrees Celsius.
I turned the sensor out and put it in the water I heated.
Its resistance changed once with water temperature changes.
IACV has a resistance of 107 ohms at around 25 celsius cells.



I bought a new IACV. In Poland, it costs around 154 USD.
I compared the resistance of the new and old (still mounted), which was almost identical.

I checked the all the wiring with an ohmmeter (SM)... OK.
There is an ECU under the fuel tank.
I took out the plugs from the ECU and checked for corrosion ... it wasn't ... perfect condition.
Prophylactically, I sprayed ECU plugs (all) against corrosion.

Next to the ECU is a screw screwed into the frame, which provides ground for several electrical components, probably also ECU.
There was patina and slight corrosion.
I cleaned the brass contacts and cleaned the frame which rusted gently in the place which is predicted for contact.

Finally, I assembled tank and wires and went for the ride test.
The problem has not disappeared.
1500 RPM was still on.


After this test, I wanted to remove the plug from IACV again, it was very hard to do that.
I accidentally moved the IACV by turning it 1-2 degrees when I tried to remove the plug.
When I discovered that IACV can be gently shifted, I moved it right and left a few times with the engine running.
At some point, the engine speed dropped from 1500 to 1000 .....UPS !!! sounds like a fairy tale of 7 dwarfs

I understood that I could have a dirty IACV or a chamber in which it is embedded.
The problem stopped ... but not entirely.

Last weekend I went with my daughter on a 400km route.
Twice it happened that idle speed dropped to 500.
Once the engine went out.

I took the motorcycle to the Honda site yesterday and IACV was replaced. (100$ only)
IACV chamber cleaned.
I asked the mechanic if it was easy to pull the IACV out of the chamber.
He replied that it was not so easy.
IACV was sitting quite tightly and it took little strength to pull it out.
I agree with this because I had to use some power to move the IACV with my fingers to the right and left.

 
Today, I drove 60 km in urban conditions ... using gears 1 - 2 - 3 - 4 - 3 - 1 (everyone knows when the problem occurs).

We'll see what will happen next ... but it looks OK for now
In addition, the motorcycle has more power and stopped smelling gasoline, which happened earlier.

In addition, about 1000km ago examined the state of exhaust gases.

It was bad.
Tomorrow I will check how it is after replacing the IACV.
I have an old IACV. Does not look worn and dirty.