RE: CB1100 Idle speed instability problem

[Houtman_imp]

So far (touch wood) I have not had any idling problems om my CB 1100's in about 45.000 miles combined on the 3 bikes. However if I do get problems the first thing I would do is to get a Japanese girl friend to help with the translation to get me on the right track ! ( with my bike I mean )

[peterbaron]

^I second that ^

[SportsterDoc]

Max: Identifying the software update for the ECU may help non USA riders.
If it is an ECU program issue, why does IACV replacement provide a cure? Not challenging the programming, but wanting to understand.

[Lambchops_imp]

Note that it is a 2014 Standard. In Japan this issue is known to affect both the EX and standard versions.

The "new" ECU software update (38770-mcg-d43_M1.rwf) was released on 2017/4/11 so it has been out for some time now.

Just to add on a few more sources for your information - summarised below (or you can google translate):

1. https://bbs.kakaku.com/bbs/K0000093499/SortID=20494876/
In this post, the author writes that he experience the idling issues and was offered to have his ECU updated. After which his issues were solved.

2. https://minkara.carview.co.jp/userid/172.../note.aspx
In this post, the author writes about the idling and stall issues. He/she indicates the Honda dealers only do this for those who complaint of the issue. And that he/she thinks that Honda is trying to avoid a recall. Also mentions that new models do not have this issue.

3. https://ameblo.jp/musumetiti/entry-12395482220.html
Another owner writes he experienced the problem of stalling in traffic jams when clutched in and found a description of the remedy of having an ECU update. So he does that and sends his bike to a Honda shop where he requested for an update. (Pictures of the update in progress are included)

[Cormanus]

It may be the result of various translations and the technology that does it, but we've now got mention of 'initializing', 'resetting', and 'updating' the ECU. Updating suggests loading new firmware that changes the programming. Heaven knows what 'initialising' and 'resetting' mean. Assuming they're different, it seems to me likely that 'initialising' may mean rebooting the existing software while 'resetting' means reloading the firmware and restarting it. Or vice versa.

Either way, SportsterDoc's question about why replacing the IACV fixes a software problem remains.

It's all too curious for words.

[Lambchops_imp]

I recall reading not all IACV replacements were a cure for it in this thread.

I wouldn't call it a software problem at the moment.

The way I see it, if a batch of IACVs were faulty, it could cause the PGMFI to misread and compensate erroneously.

The solutions would then be to 1) replace the IACVs affected or 2) rewrite program to ignore such reading/change its compensation response.

Since this problem is not widespread, it would cost more for the manufacturer to recall all vehicles to replace the IACV. Instead they opted to go for option 2) which is to "update" the PGMFI software for customers who complained about the issue.

Just a guess.

[Cormanus]

That’s a possibility, Lambchops. Strange Honda doesn’t seem to have mentioned it to anyone in the US.

[Lord Popgun]

If you remember, Honda of America denied any software update was available even as members in Europe were getting it.

[pdedse]

If you remember, Honda of America denied any software update was available even as members in Europe were getting it.

True. A Honda of America customer service person reached out to me by phone in response to my letter that explained the situation. I read a post from this site from a member in Europe whose bike was fixed with a software update.

The CS person said Honda of America didn't have any information regarding such an update--and that she would have that info if there was one for the U.S.

She also pointed out that there was no way of knowing whether the underlying cause producing my bike's issues was the same as that of the bike in Europe, despite the similarity of symptoms.

The only recourse she recommended was to let the dealer diagnose the problem, have the bike fixed and then submit "everything" to Honda America to determine what might be done, if anything.

[max]

Lambchops thanks again, as far as we know there was one member who initially still had the problem after replacing the iacv but later reported that the fault had cleared some time later, so far all repairs have had success and i don't know of any cases where the fault has returned.

Doc at this stage with the information we have i tend to think that the pulses are just long enough to move the iacv but over time some iacv's deteriorate enough ( remember it's bolted to the aircooled cylinder head ( a hot place ) has permanent magnets inside it which don't like heat and it often starts in slow traffic ) that the energy in the pulses is not sufficient to move them the small steps and they loose the ability to return to 1050 rpm in one direction.

Cormanus "resetting" means the microprocessor stops running everything and start again, this is done at switch-on.
When it starts again it "initializes" meaning clears working memory, starting from command line zero and setting up everything it needs to run the program, setting chip pin allocations, checking sensors and switch positions, run fuel pump, sets up iacv in correct position and when all is successfully set up it responds by displaying the meter sweep in our case.
"Updating" means clearing a previous program ( a set of checks and instructions, "rules" if you like ) and loading a new program line by line ( hence the green progress bar ) into the allocated memory location for that new program ( there are several different memory locations in an ecu for different purposes for instance the hiss data has another location.

As customers communicate on a forum to compare situations they may use slightly different words for what they mean but when we look at lambchops pictures it confirms loading a new updated software version into the ecu overwriting the previous version.
Since the previous version is not released it is not possible to revert back to it, it has been erased by the new update.

My sense is that the japanese have a closer relationship with the factory, speak the language and know who and how to approach the problem hence the availability of the software.
The software update version 3 could have unintended consequences if applied in the wrong situation hence the limited application of it to a small group of affected customers instead of a recall.
So the technician's response may be;
ああそうだね、あなたのバイク用のソフトウェアアップデートがある
Ā sōda ne, anata no baiku-yō no sofutou~eaappudēto ga aru
Rolls his laptop trolley over to the bike and puts in a new set of one's and zero's.

So armed with a set of pictures of the software update and the filename of this update we may now have a better shot at explaining to the worldwide dealer network where necessary fixing this problem which is why i collected all relevant info into one post with the great help from lambchops.