CB1100 Idle speed instability problem

[Nachodaddy]

Spent the afternoon reading through this long thread and found that it occurred on a few 2013s over the years. While it looks like a replacement of the IACV is the cure, I want to see how the bike responds to a few things first. I will keep you posted. I won't be doing anything drastic for awhile.

 

[Cormanus]

Apologies Nachodaddy. Yet again my memory is failing me. It will be good to hear what you come up with.

 

[pdedse]

Here we go again.
I bought my 2013 standard in August, 2021 with around 4500 miles on it. A very clean bike that looked well cared for. I don't ride much, but recently the idle will suddenly drop to around 500 RPM and the engine will die. This first happened when I was riding very slowly, using the clutch to regulate my speed while practicing very slow speed turns, figure-eights and U-turns in an empty parking lot. Then it happened after riding fairly fast and stopping at a traffic light. Clutch pulled in, bike in 1st gear, engine idles down to 500 for a second or so and dies. This happened a few more times on the way home. The bike is hard to start when this happens. Enough so, that other traffic is getting irritated with me and I have no place to move the bike, but have to keep trying.
I will take it out and see if a few things help, like putting it in neutral and leaving the clutch out when I start it, turning off and on the master switch before starting it after it dies, and rotating the throttle completely each time.
I think it is too old for Honda to give me any kind of warranty coverage and I have absolutely no confidence in any of the local "Honda" shops.
Weather at this time is very mild - sixties to mid-seventies (F) dry air, typical desert winter weather. I very much appreciate all the posts, attachments and pictures others have posted of their experiences with this problem. If I had been smart enough to read this forum before buying this bike, I would not have bought it, especially at the price I paid.

Sorry for your idle troubles. When my '14 standard started acting up, it was about 6 months out of warranty. I thought Honda might step up to help with the issue and wrote them a letter explaining everything, and the fact that some 25 other owners had experienced this on this site, and asked them to please consider extending warranty. Customer Service called me a few weeks later and asked questions, was sorry to hear of the difficulty...but bottom line was--you have to take it to dealer and let them diagnose the issue, and after that Honda would take it into consideration. Dealer said it could be hard to diagnose because the issue was intermittent, and if time were spent trying to make the problem happen, that would be time charged at $125 per hour. Sevice manager said he had seen cases where he thought Honda should cover things, but didn't and sometimes the reverse--he simply had no way of knowing what they would do. In the end, leery of a long drawn out ordeal, I decided not to go that route and simply traded it in on a new bike. But at the time 2016-17, not as much was known about the likely culprit...the IACV.

 

[Enzofour_imp]

I speak from direct experience, do not waste time with useless attempts, replace the IACV and solve the problem forever.
Enzofour

 

[Nachodaddy]

Apologies Nachodaddy. Yet again my memory is failing me. It will be good to hear what you come up with.

No worries, my friend. If only I could replace my memory as easily as replacing the IACV. :beerchug:

I speak from direct experience, do not waste time with useless attempts, replace the IACV and solve the problem forever.
Enzofour

Enzo, I am encouraged by your replacement of the IACV without removing so much from the bike. It would be helpful if you could list where you started and how much you removed and what problems you found and how you over-came them on the way. Thank you for your encouragement.

 

[1973cb750]

Today the Honda dealer informed me that in 2016 Honda sent dealers an ECU update.
This update was not an official reminder, but a tip to use on 2014/2015 models with low idle and shutdown issues.
On 14/04/2021 they will install this update for me, we will see the effects.
I will try to get the name / code of the firmware for this update.
Meanwhile, with the replacement of the IACV the bike didn't give me any more problems.

i wonder if the usa will get this? mine has zero issues '14

 

[Enzofour_imp]

[/QUOTE]
Enzo, I am encouraged by your replacement of the IACV without removing so much from the bike. It would be helpful if you could list where you started and how much you removed and what problems you found and how you over-came them on the way. Thank you for your encouragement.
[/QUOTE]


First you need to get a long and flexible Phillips screwdriver, otherwise you will not be able to unscrew the central screws of the airbox box (see arrows).
With a lot of patience you have to free the airbox of all the cables it supports and all the various pipes connected to it, I recommend you take many photos before disassembling the various pieces, so you can put everything back as before.
You will also need to unclip some electrical connectors to make room for yourself.
Now loosen the sealing ring between the airbox and the airbox (long screwdriver),
Here you have to use the flexible screwdriver to be able to unscrew the central screws that separate the airbox cover from the plate that contains the flutes of the throttle bodies. ATTENTION! the box comes out from the right, but the space is insufficient so you have to heat the box with the hair dryer or heat gun, in order to make it elastic and withstand the effort, same thing when you reassemble it. ATTENTION! in the upper internal part you will see a joint, when reassembling it you must match it in the right way (take pictures first).
Now you can replace the evil IACV.
Do everything calmly and before starting and while you take apart the parts, take your time to look and evaluate how best to do it, I watched it for 1/2 day before starting.
Good job.

 

[Nachodaddy]

Thank you Enzo, this is very thorough and helpful.

 

[Houtman_imp]

I never had an instability problem on any of my CB 1100's but that is a very good post from Enzo !

 

[max]

That's incredibly helpful Enzo, i'm sure a lot of people will be grateful for your input, very skilled and dedicated work ( and i like the clock.....) my kinda guy as you sit down with some coffee and nut it out in your head :worship:.

Maybe it is clear what to heat at the airbox to be able to pass it through the frame but if you can elaborate which part you heated up that would be even better for the future ( and do you rotate the airbox? ), i like to be as complete as possible to facilitate the next guy.

And Nacho; mark the new iacv before swapping it out somehow ( you know ? )

What was the NEW partnumber for the iacv anyone ?

Moderators would it be possible to copy Enzo's post to the how-to section so it does not get buried in the thread?

Also copied the entire post to my harddrive and baptized it " THE ENZO METHOD "

 

[Nachodaddy]

Yesterday after 1 hour on the road it turned off, it no longer held the minimum.
She turned off and on again, by turning the key, and left again normally.
After another hour of travel it is off, I repeat the procedure of turning it off and on with the key and it takes me home without any problem, 20 minutes of road practically in first and second gear due to traffic.
When I get home, I leave it on for a while and accelerate, nothing happens, at least very regular.
Who can tell me if the new IACV cod. Can 16431-MGZ-D01 fitted on 2017 and later models be used on pre 2017 models? Honda cod. 16430-MFJ-D01

Note: the temperature was only 22°

As far as I can tell, no one answered Enzofour's question about using IACV 16431-MGZ-D01 (for 2017 and up) in place of the 16430-MFJ-D01(for pre-2017). Enzofour, which part number did you install on your bike?
Thank you all for your help.
PS, I did notice that one post got the part number as MJF instead of MFJ. Google corrected me, but it could cause some confusion.

 

[Enzofour_imp]

That's incredibly helpful Enzo, i'm sure a lot of people will be grateful for your input, very skilled and dedicated work ( and i like the clock.....) my kinda guy as you sit down with some coffee and nut it out in your head :worship:.

Maybe it is clear what to heat at the airbox to be able to pass it through the frame but if you can elaborate which part you heated up that would be even better for the future ( and do you rotate the airbox? ), i like to be as complete as possible to facilitate the next guy.

And Nacho; mark the new iacv before swapping it out somehow ( you know ? )

What was the NEW partnumber for the iacv anyone ?

Moderators would it be possible to copy Enzo's post to the how-to section so it does not get buried in the thread?

Also copied the entire post to my harddrive and baptized it " THE ENZO METHOD "

The part to be heated is the whole airbox, excluding the air filter container, which was previously moved back after loosening the metal ring that holds it anchored to the airbox.

 

[Cormanus]

Enzofour's method is now in the How To section.

 

[whizzle_dizzler_imp]

Alright guys. So I've been dealing with this issue since last summer, when I started noticing sitting in traffic, the revs would drop low to around 600-800 rpm. I ride year round in the Triad area in NC. During the mild to cold weather, the revs would remain high, and maybe for a golden 5 minutes after starting the bike up at work to make the 20 mile commute home, it would act normal. However, all other times, it has pretty much all of the symptoms of the IACV issue. Let me list them just so we're on the same page.

- Normal idle rpm in neutral
- Shift into gear - crack open the throttle, hangs out at around 1500+ rpm until it decides to maybe drop down to 1100-1200rpm.
- Clutch in at a stop in 1st gear, normal-ish idle. Release the clutch only slightly, revs start to ramp up 2k+ as the clutch is released.
- Clutch fully released, revs drop to around 1600 rpm, still uncomfortable in some low speed situations. I need to use more rear brake for the low speed maneuvers than I should have to, as the bike is ramping up the revs without my input.
- Highway, slowing down from approx. 60-70 mph, let off throttle, rev match to downshift a gear, release clutch properly, *clunk clunk clunk* as the bike bucks and tries whatever it is doing. This does not happen 100% of the time, but I can feel the rev hang (engine braking is NOT consistent) while letting off the throttle in gear. Feels like a super lazy cruise control. Letting off throttle barely slows me down in the higher gears.

SO I think that's it as far as symptoms. I'm prone to forgetting some things, but I think that's pretty accurate. I've experienced all the issues.

I went ahead and went on eBay and bought a used '12-'16 CBR1000RR throttle body for $60 with a factory IACV, because I am a cheap b*sterd. I just finished up the IACV swap this last weekend, put everything back together, and after 95 miles of commuting, the idle issue is STILL existent.

I have not looked into if the CBR1000RRs had idle issues like ours, but I was hoping that the idle issue was only isolated to the relatively smaller batch of bikes that is the CB1100. Although I swapped it with a used part, I find it unlikely that I'd have the exact same issues as before, unless there was a deeper issue, such as the ECU.

I really love this bike and I plan on keeping it until it's completely roasted, but this issue is really killing my affection for it.

I really would like to have a good known ECU in hand so I can rule out that it might be an ECU issue. If anyone has one I can rent or borrow for troubleshooting, that would be fantastic.

Of course, any other suggestions other than buying a brand new IACV, and still having the same issues, would be welcomed as well.

Cheers :beerchug:

 

[SportsterDoc]

Do I understand correctly that the IACV swap was with a 6-10 year old used IACV from a '12-'16 CBR1000RR?
Any testing done on the used IACV?
Both IACVs have same part number?

 

[Nachodaddy]

Several people have claimed success with different fixes. Dave and I think Enzo, said a new IACV solved the problem, but that is a very expensive fix if it doesn't work. Someone else claimed a new coil-set, and plugs did the job. Could it be that many of these bikes with very sophisticated electronics and fuel systems have gone years sitting in the garage and are simply showing what happens when such complex machinery isn't used?

 

[whizzle_dizzler_imp]

Do I understand correctly that the IACV swap was with a 6-10 year old used IACV from a '12-'16 CBR1000RR?
Any testing done on the used IACV?
Both IACVs have same part number?

...Just got back from bombing some roads on the 954RR.

Yessir, from my understanding, the throttle body was pulled from a running CBR1000RR. I bought the assembly back in mid-December 2021, so I can't look at the original eBay listing to ensure there wasn't some weird stipulation with the part, but I did a lot of shopping before I went ahead with the purchase.

No testing was done on the 1000RR's IACV. (Did not look into this, as I hoped throwing random parts at the motorcycle would magically solve it!)

Both bikes share the same IACV part numbers, as referenced by BikeBandit's site: 16430-MFJ-D01

...along with being shared with maybe 6-8 different bikes approximately, so I figured the 1000RR was more common, I could tinker with the throttle body as a freebie, and hopefully solve the problem on the cheap.

I'm not too worried about "old" parts, especially with the alleged good quality of modern manufacturing. However, seeing that it is a Honda, and their old 90's era cars were always plagued with wacky IACV's.... Maybe I should buy a brand new parts... but I threw the dice, and I may have lost some money.

So here we are. I'm able to have the CB1100 down indefinitely since I have another bike to ride. I quick searched "test IACV on here" and didn't come up with anything. Point me in the right direction, and I'll test the original, and the 1000RR's, and hopefully add something useful to this thread.

 

[SportsterDoc]

There are FSM tests, but they may be inconclusive

Really high idle

 

[max]

As you may have read some lucky members have permanently fixed their issue with a software update, not possible in the us, e.p.a. is a scary thing so the dealers are not prepared to risk their business i believe.

Every single cb with this issue ( mostly the 2014 models ) started good as gold but something changed over time and we never saw any wear or dirt in the valve body, so what gives?

And i don't know of any member who did not have success with a new iacv, to me it is the lack of control from the ecu,
( hence the software " update " ) i think the older iacv's permanent magnets have degraded to the point where they no longer control the iacv correctly.

A lot of times this has happened after the engine has been very warm, permanent magnets lose magnetism if the temperature rises, the iacv is in a hot place and that is why i have come to this conclusion.

You may be in a unique position to evaluate the " magnetic torque " difference between an old and a new one firsthand.........

Haya Doc.

 

[Enzofour_imp]

When I replaced the IACV, a few days later the dealer installed a software patch that he had received from Honda in 2014 to fix the low or high rpm ramdom problems.
I haven't had any issues to date, but I can't guarantee if the solution was the IACV replacement or the patch or both.