CB1100 Idle speed instability problem

[max]

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.

[pdedse]

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.

[syncronizator_imp]

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.

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.

[Speed_imp]

Sorry Pavel, did you say that low idle problem came back after IACV replacement?

[syncronizator_imp]

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

[SportsterDoc]

The IACV has been the conclusion for a couple years.

http://cb1100forum.com/forum/showthread....#pid189695

Post 638 (Dec 2017) see items 1 & 2

http://cb1100forum.com/forum/showthread....#pid252433

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.

[Speed_imp]

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

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
https://www.youtube.com/watch?v=aT2bjVxi0qo

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]

185 Euros = $203 US dollars?
Dave posted photos in post 911 that may be of help to anyone replacing the IACV.
http://cb1100forum.com/forum/showthread....#pid207298

[Speed_imp]

185 Euros = $203 US dollars?
Dave posted photos in post 911 that may be of help to anyone replacing the IACV.
http://cb1100forum.com/forum/showthread....#pid207298

Thanks, this is very useful, not removing de throttle body saves a lot of possible trouble

[syncronizator_imp]

185 Euros = $203 US dollars?
Dave posted photos in post 911 that may be of help to anyone replacing the IACV.
http://cb1100forum.com/forum/showthread....#pid207298

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.