CB1100 Idle speed instability problem

Pavel thanks for all this detailed explanation, is it possible for you to connect the old iacv to the connector on the bike and see how easy it is to stop the stepper motor ( "exhibit A" ) from turning?

A video would be even more helpful......

We have never had a dirty chamber reported, the air through it is filtered and mixed with a very small amount of blowby gas from the crankcase ventilation, the "square" intake chamber for the iacv can be seen below the iacv in between the two t.b. intakes.
This same throttle body has been used on several types of Honda bikes and does normally seem to have no problems, it's only some of the 2014 models that are affected and we don't yet know why.
 
My '14 had the problem, but I gave up on it and traded it in. So, kudos to all you working on this, as it is fascinating to me.

All the exchanges here reminded me of this scene from Apollo 13:



"We gotta to find a way to make this...fit into the hole for this...using nothing but that" (0:48-0:58).

In the end, they did find a way...I hope the same for all involved here.
 
max_imp said:
Pavel thanks for all this detailed explanation, is it possible for you to connect the old iacv to the connector on the bike and see how easy it is to stop the stepper motor ( "exhibit A" ) from turning?

A video would be even more helpful......

We have never had a dirty chamber reported, the air through it is filtered and mixed with a very small amount of blowby gas from the crankcase ventilation, the "square" intake chamber for the iacv can be seen below the iacv in between the two t.b. intakes.
This same throttle body has been used on several types of Honda bikes and does normally seem to have no problems, it's only some of the 2014 models that are affected and we don't yet know why.
Click to expand...

Yes MAX of course I will.
However I would like like to go for a few trips first in the upcoming weekend and finish the test that will answer the question whether replacing the IACV solved the problem.

I do not want to spoil the IACV adaptation made by the HONDA service.
Let's give the current situation a chance to prove whether the IACV exchange helped.

Recently, the problem occurred again after driving 200km.
For the 200km nothing indicated a problem.

I asked the mechanic how big the dirt was in the chamber.
He claimed that it was a rather thin layer that could be wiped easily with a finger.

Personally, I think that if IACV could be shifted back only 2mm so that a slot was created and then turn on the engine and finally let the vacuum suck in some fluid like WD-40 or chain cleaner , then IACV would be washed without disasambling half of the motorcycle.


My other idea is to let WD-40 by putting my hand into the air filter housing .... but I'm not sure if there is a place where the vacuum would suck WD-40 into the IACV chamber ...

Maybe a smal video camera could show where to inject dirt cleaner ?
Another idea is that IACV may be clean but its electrical properties may have changed and is worn and finally not changing its position as it should.
 
Hi Speed ,
I replaced IACV Wednesday and immediately i did the 60km test ride without idle problems.
Today i did second test ride 125km and still no idle problems.
Cold engine work on 1400 RPM and after 2 minutes 1300 and after nexst 3 minutes it gos to 1000RPM

Until now no issues. .... don't worry i understand Your pain. I will report every day.

I don't want to announce the verdict to early ..but until now IACV replacement solved the issue for my bike.

Paweł :)
 
The IACV has been the conclusion for a couple years.

CB1100 Idle speed instability problem

Post 638 (Dec 2017) see items 1 & 2

CB1100 Idle speed instability problem

Post 1012 (Oct 2019)

"From reviewing recent posts on this thread and the Curley Joe Spreadsheet, I am inclined to conclude that most issues are IACV and/or ECM program related, with the exception of a damaged TPS wiire and maybe one EOT."

With the stepper motor resistance checks in spec, perhaps blowby containation is an issue. If so, cleaning may be all that is needed, but comsidering the labor investment, replacing IACV may still be wise.
 
syncronizator_imp said:
Hi Speed ,
I replaced IACV Wednesday and immediately i did the 60km test ride without idle problems.
Today i did second test ride 125km and still no idle problems.
Cold engine work on 1400 RPM and after 2 minutes 1300 and after nexst 3 minutes it gos to 1000RPM

Until now no issues. .... don't worry i understand Your pain. I will report every day.

I don't want to announce the verdict to early ..but until now IACV replacement solved the issue for my bike.

Paweł :)
Click to expand...
I have just ordered a new IACV valve in order to replace it as soon as it arrives. As SportsterDoc said maybe it is wise just to replace it given the high probability (and cost: valve, o-ring and deliver about 185€). I sent a message to the German dealer who made the repro to Wisedrum but no answer from them yet and my dealer in Spain seems not to know about that Software update. Still I am wondering why after a pulse train the idle drops.

Pulse train and idle lowering at 0:35

1- Pulse train trying to open the valve but the valve closes instead - Bad IACV
2- Pulse train trying to close the valve and the valve closes thus lowering the idle - Wrong output from ECU

Just let's see how it behaves when replacing IACV.
 
SportsterDoc_imp said:
185 Euros = $203 US dollars?
Dave posted photos in post 911 that may be of help to anyone replacing the IACV.
CB1100 Idle speed instability problem
Click to expand...
Yes.
Prices for Honda parts in Europe ale much higher then in US.

Coming back to Topic...., today was a test 3.
I have driven 245km since replacing the IACV
No idle issues so far
I was riding today in very cold and intensive rain.
I arrived completely soaked but happy.
 
Gratuluję sukcesu

In trying to figure out if there is any correlation of IACV issues to riding style, would you mind ansering a few questions related to possible blowby contamination?

1. How often do you ride on errands less than 7 miles?

2. What oil are you using?

3. What is the longest time interval between oil changes?

4. What is the longest mileage interval between changes?

5. How often do you accelerate briskly?

6. What is your typical cruising speed?

7. How often do you ride?

8. What is the longest time interval between rides?

9. What is you engine warm-up proceedure?
 
SportsterDoc_imp said:
Gratuluję sukcesu

In trying to figure out if there is any correlation of IACV issues to riding style, would you mind ansering a few questions related to possible blowby contamination?

1. How often do you ride on errands less than 7 miles?

2. What oil are you using?

3. What is the longest time interval between oil changes?

4. What is the longest mileage interval between changes?

5. How often do you accelerate briskly?

6. What is your typical cruising speed?

7. How often do you ride?

8. What is the longest time interval between rides?

9. What is you engine warm-up proceedure?
Click to expand...
 
Zapraszamy

Thank you for the fedback.

Not seeing any issue with your riding habits, other than probably good for injectors to be opened up occassionally by WOT runs to 5,000 RPM in lower gears.
 
max_imp said:
Pavel thanks for all this detailed explanation, is it possible for you to connect the old iacv to the connector on the bike and see how easy it is to stop the stepper motor ( "exhibit A" ) from turning?

A video would be even more helpful......

We have never had a dirty chamber reported, the air through it is filtered and mixed with a very small amount of blowby gas from the crankcase ventilation, the "square" intake chamber for the iacv can be seen below the iacv in between the two t.b. intakes.
This same throttle body has been used on several types of Honda bikes and does normally seem to have no problems, it's only some of the 2014 models that are affected and we don't yet know why.
Click to expand...
Hi MAX ... , I am ready to perform this test this week. (video )
Lets agree.. how to run the test to cover all needed scenarios.
What do you mean by "exhibit A" .... ?

My IDEA is to prepare (will try to do) a kind of pipe with slot and pin to do a simulation for IACV chamber and finally simulate IACV work in it.
 
Hi Sinc, good questions, Exhibit A is the old iacv as show in your ( neat ) picture, did you clean it or was it like new?.

Here's what we would like in the "shot'"

Before turning the key on; disconnect the iacv, the engine will run slow and may need some help from the throttle, or;
let the iacv position itself so the engine will start in 1500 rev's, and stop the engine with the key, ( the iacv will stay in that 1500 position ) and then disconnect the iacv,
your choice whichever works best and does not overheat the engine during the test.

No need for an artificial cylinder, it would probably mis-align anyway, just hold it with two fingers and stop it from rotating that will be fine as far as i can see.

1 During startup cycle try to see how strong the stepper motor "A" is by just holding the piston and pushing against the
direction of travel to see how much force it takes to get it "stuck" , you may need a helper for this to switch the bike on several times my guess is that it retracts completely and then extends by a certain amount of steps, this is done very quickly so if you have a high framerate cam that would capture it better.

And with the engine running;
2 movement of "a" on initial statrup moving back and forth, with the iacv not in control of the rev's it may have some unsuspected behaviour but that may work in your favour .
3 movement of "A" during warming up and slowly extending
4 same when blipping the throttle.

Engine off;
5 what is the function of the spring inside the piston ( show movement )
6 how much sideways play does the spindle have ( is it sloppy or does it have good bearings).
7 is the thread worn inside the piston?
8 anything i forgot;)

You may have noticed that the pulses during normal use can be a lot shorter which means less force to move the piston even in LP's engine, if you can be aware of this as well.
We've always wondered what the motor actually does but no-one has had the opportunity to explore this, so we are very lucky that you can help us understand how this functions and how the engine control unit works.

also when the tank is lifted for access check that the fuel connector is secure over the fuel pipe after the dealer,s repair.

By the way i looked at a cb1000r forum and one of the members also had his iacv replaced ( under warranty ), repair confirmed and the complaint was " it just died, fired up and died again", hmmmm :s
Same iacv in a similar throttle body.
 
Max,
there is brand new IACV on my last the picture.
The old one looks like new too.
I haven't seen a chamber... but I don't have report that it was heavily soiled.
I was only a small layer and very easy to remove.
I told to Mechanic ... "please don't clean old IACV".
It was only a thin layer of soft dirt .
Now I wish I had done it myself.

I understand that engine should be cold before I'll provide the test.
Than, test is possible only Saturday ...because i ride to work everyday and come back home around 7PM... so the engine is warm.
Today i will post the pictures of old IACV and its components.
I will do the video to show how works the spring inside the cylinder.
 
Do anyone know what voltage the IACV is running on?
12V or less ?
I have a DC power supply with variable voltage.
I can power it, e.g. 7v

Which contacts are responsible for turning IACV left and which ones for turning right?
 
Based on what the o-scope shows, 12v.
 
syncronizator_imp said:
Do anyone know what voltage the IACV is running on?
12V or less ?
I have a DC power supply with variable voltage.
I can power it, e.g. 7v

Which contacts are responsible for turning IACV left and which ones for turning right?
Click to expand...
all 4 pins are receiving 12V pulses

- 2 pins for each coil
- they receice 12V 1 pin and ground the other pin of the same coil
- Every pulse will move the rotor to the next pole or magnet
- I think the way it turns right or left is changing the order the pins receive 12V

I am not really shure it is working like that but what I saw with only one channel of the scope make me think that, just waiting for a second probe for the osciloscope in order to monitor exactly what signals are receiving each one of the 4 pins while opening or closing the valve.

Another test is to measure the resistance of each coil while heating up the valve (it is known coils are prone to fail with different temperatures as observed in many ignition coils) or to hit the valve with while measuring the resistance.
 
My old IACV phisical condition:


---------------------------------

Speed ​​,
I want to test IACV by connecting it to the power supply.
I want to see if it turns with the same power to the right as to the left.
I don't want to damage the IACV by wrong connection to 12v power supply.
There are 4 connectors.

According to SM one coil - two inside connectors
second coil - to outside connectors


Question:
If I connect the IACV in the wrong (reverse) polarity can I damage the IACV coil ?
 
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