CB1100 Idle speed instability problem

[peterbaron]

2 x pm sent

[Lord Popgun]

Pb,

That is a chassis ground on pins A23 and A24. They go to Popgun 1 and Popgun 2. The ground is supposed to inhibit snarky posts like this one. Doesn't work, as you can see...

[Lambchops_imp]

Hi everyone it's me again back to share my experience with the idle instability issues after 3 years.

I posted in 2020 about findings in Japan that dealt with the idle issues via a ECU update here: http://cb1100forum.com/forum/showthread.php?tid=15710

It seemed like the general consensus then was that it is an IACV issue and not ECU. But lately, from what i've read it sounds like the ECU update patch has been shared with EU and has worked. Also, it appears that the older ECU part numbers have been superseded with a newer part number.

I have replaced my IACV twice and still encountered the same issues so I believe it it might be solved with either an ECU update or a new ECU.

DDUMZI has shared his experience here with his ECU: [url=http://cb1100forum.com/forum/showthread.php?tid=18035&page=7]http://cb1100forum.com/forum/showthread....035&page=7

I'll update again if an ECU replacement solves the issue. Wish me luck

[Cormanus]

Good luck, Lambchops!

[louied_imp]

How difficult is ECU replacement? Does anyone have a set of procedures?

[Lord Popgun]

Oh man, its really tough.

OK, not really Its under the tank. Basically, remove tank and then just unplug it and remove it from its holder. There are pictures of it on the site somewhere. Unless someone posts a more detailed answer, I’ll search for them later.

[Nachodaddy]

How difficult is ECU replacement? Does anyone have a set of procedures?

It is easy, but takes patience and time. Read all of this first.

1) Empty your fuel tank. The lighter it is, the easier this will be. Remove the fuel tank. This is the hardest part. The fuel lines are connected with a green and black rubber connectors, seen here after disconnected:

The green part is inside the metal fuel line. The black part slides back and forth to hold the green part inside the tube.
In this diagram, number 11 is the green and number 3 is the black piece
You have to disconnect these to get the tank off the bike. Remove the bolt at the rear of the tank and lift it as high as you can. It will only go up an inch or two and that is why it is hard to do. You have to get into that space to disconnect these connections. Most of us prop the tank up with a piece of wood or rolled up towels. I found some old, hard sponges that worked good. It is easier with small, hard, tough hands. You will want some kind of light to see in there because it is dark and these are small pieces. Putting it back together is no easier.
As Popgun said, once the tank is out of the way it is just plug and play. Unplug and discard the old one and plug in the new one. Probably should remove one of the leads from your battery first, too.
My bike is a 2013 standard, so yours may be different if it is another year, but the connectors are probably the same. I threw away what was probably a good IACV yesterday. It was the one I replaced before realizing that it wasn't the problem. Good luck.

[louied_imp]

Thanks!

[Lord Popgun]

Thanks Nacho! I didn’t have the time this morning for the whole procedure. Plus, you have nice pics.

There is a change in the quick disconnects, but I forget what year the change was made. Maybe in ‘17. There are procedures in the How to section.

[Nachodaddy]

Thanks Nacho! I didn’t have the time this morning for the whole procedure. Plus, you have nice pics.

There is a change in the quick disconnects, but I forget what year the change was made. Maybe in ‘17. There are procedures in the How to section.