CB1100 Idle speed instability problem

[the Ferret]

Again, not trying to minimize, trying to get a scope on how large the issue is.

We have a guy with 2200 miles on his bike without an issue, but he is wondering if it is something he should be concerned over.

Unfortunately we have no idea how many CB's are sold world wide or how many are affected. If it is 1% of units affected there is no need for concern... If it were 50% affected it would be like facing an epidemic of cholera or something. I have a feeling its more the former than the latter, but truthfully we just don't know.

 

[johnf514_imp]

Chiming in again for new members with my experience.

Bought a 2014 CB1100 EX with 6100 miles on it in Feb 2016, with over one year of warranty left.

Issue occurred three times over the last 10 months (high idle condition). The first two times, the dealership reset the ECU, which treated the symptom, but did not resolve the issue, and the high idle condition returned.

The third time I took the bike to the dealer, I demanded that they keep the bike until the issue was resolved before resetting the ECU. Honda sent a tech to the dealership and they determined the IACV motor was sending faulty information to the ECU, thus causing it to enter "limp mode." The dealership replaced the IACV motor (this was 3 months ago) and the issue has not returned.

I have 3 more months of warranty left, and I hope the condition does not return. Let me know if you have any questions.

 

[the Ferret]

The IACV motor .. Is that part of the throttle body assy that Rico had replaced? or a separate part? Mechanical or electronic?

 

[Lord Popgun]

It is mounted in throttle body assm. It is stepper motor that moves a needle. So it is electromechanical.

The TPS is also on the TB assm.

 

[Cormanus]

Chiming in again for new members with my experience.

Bought a 2014 CB1100 EX with 6100 miles on it in Feb 2016, with over one year of warranty left.

Issue occurred three times over the last 10 months (high idle condition). The first two times, the dealership reset the ECU, which treated the symptom, but did not resolve the issue, and the high idle condition returned.

The third time I took the bike to the dealer, I demanded that they keep the bike until the issue was resolved before resetting the ECU. Honda sent a tech to the dealership and they determined the IACV motor was sending faulty information to the ECU, thus causing it to enter "limp mode." The dealership replaced the IACV motor (this was 3 months ago) and the issue has not returned.

I have 3 more months of warranty left, and I hope the condition does not return. Let me know if you have any questions.

John, to be clear, you're in the US, right? Did you buy an EX—the European model—or the DLX model sold in the US? If so, you are, as I recall, the only DLX owner to report this issue.

 

[curlyjoe]

Here's a wiki link that explains how the IACV works. Apparently the motor/valve can stick and thus cause idle control problems,

The same part is used on a lot of different Honda motorcycles (from 2007-2015) including all CB models in the states. [url=http://www.partzilla.com/parts/detail/honda/HP-16430-MFJ-D01.html]See link for list

If its the IACV, wouldn't also be a potential problem on all the other Honda bikes that use the same part? There is a 4P connector that plugs into the IACV so maybe corrosion could be more of a problem on the CB since it's a "naked" bike and thus exposed to the elements (including exuberant cleaning with a pressure washer) more than the other honda models.

So far I haven't had a problem with my '13 (16.5K miles).

 

[johnf514_imp]

Chiming in again for new members with my experience.

Bought a 2014 CB1100 EX with 6100 miles on it in Feb 2016, with over one year of warranty left.

Issue occurred three times over the last 10 months (high idle condition). The first two times, the dealership reset the ECU, which treated the symptom, but did not resolve the issue, and the high idle condition returned.

The third time I took the bike to the dealer, I demanded that they keep the bike until the issue was resolved before resetting the ECU. Honda sent a tech to the dealership and they determined the IACV motor was sending faulty information to the ECU, thus causing it to enter "limp mode." The dealership replaced the IACV motor (this was 3 months ago) and the issue has not returned.

I have 3 more months of warranty left, and I hope the condition does not return. Let me know if you have any questions.

John, to be clear, you're in the US, right? Did you buy an EX—the European model—or the DLX model sold in the US? If so, you are, as I recall, the only DLX owner to report this issue.

Cormanus, I have an all-black 4-into-1 exhaust with alloy rims. Not sure where that lands me.

 

[the Ferret]

John I think that landed you in FLA with a 14 std.

wow more stuff I don't understand even after reading it lol. It's like reading Kevin Cameron.

Yes one would think it would be an issue on any MC it is used on and with Hondas it looks like it's used on 500's, 600's, 1000's and 1100's.

Popgun so if the throttle bodies are replaced then the IACV and TPS are automatically replaced as well? or do they use a new throttle body and the old ICAV and TPS's?

 

[Aussieflyer]

This problem has not shown up on my '13 (yet!!) however if it does then this discussion and this latest pieces from Johnf514 and the references from Curlyjoe seem really pertinent, they may have 'hit the nail on the head'.

WRT problems only on some bikes and not all - Perhaps it is just corrosion as pointed out by Curlyjoe but could also be that auto manufacturers source parts from multiple suppliers and definitely in different batches. These are complex systems so there could be much more to the whole story but I hope not for the sake of us backyard mechanics who will try to fix it.

Anyways, I don't know anything about this problem but am impressed with the group's contributions. Great work guys ... that's the power of sensible forums like this one.

 

[the Ferret]

2017 will be the CB's 8 th year of production. As far as I know or can recall no issues showed up until the 2014 or 2015 EX's.

At any rate working together, keeping each other informed of issues, theories, things tried, results and solutions, we are all better off for it. I too am impressed with everyones contributions, and appreciate the collective effort.

 

[Lord Popgun]

Ferret, if you look at a parts list, you will see that you cannot order the Throttle body without a new IACV and TPS.

The IACV is available separately, the TPS is not. (If you remember, sometime ago a member did post an alternative that can be used if a TPS goes bad. And how to adjust it.)

Curly, depending on how the IACV is implemented on other bikes, I can see how it could be a problem. Assuming its getting stuck or sticking and not a motor failure anyway.

 

[curlyjoe]

Ferret, if you look at a parts list, you will see that you cannot order the Throttle body without a new IACV and TPS.

The IACV is available separately, the TPS is not. (If you remember, sometime ago a member did post an alternative that can be used if a TPS goes bad. And how to adjust it.)

Curly, depending on how the IACV is implemented on other bikes, I can see how it could be a problem. Assuming its getting stuck or sticking and not a motor failure anyway.

Good point popgun.

Aussieflyer also had a good point in that it could be a parts supplier QC problem.

Even though I don't have a problem with my CB, this problem is really bugging me. Maybe I'll go through all the old threads and see if I can find any more clues. I think Riko's CB had the most severe problem along with some of our fellow CB owners in Asia. Most of the others reported unstable idle rpm or stuck at high idle rpm. Odd too that most if not all reports are from 2014+ CBs. Is the latter accurate? I think Rolls has a '13 that had a transient idle problem and one member had a '13 stuck at high idle but that was a problem with a faulty Oil temperature sensor.

 

[Cormanus]

And now Flynrider has reported a hint of a problem with a 2013 bike.

 

[flynrider]

Yep. It was only transient and it went away after the bike was restarted, but it was definitely abnormal. I've put over 17K miles on the bike over the last 3+ years and it's never done that before.

At this point I wouldn't call it a problem, but you can bet I'll be keeping an eye on it. When I first saw the low idle, I was immediately reminded of all of the posts I've read here on the subject of idle irregularities.

 

[Lord Popgun]

Curly, When Rico first started reporting problems with the EXs my thought too was a bad run of IACVs. But then when the problem started showing up on other models I wasn't so sure. Maybe some of the problems, like Flynrider's, are a little water in the fuel. Or maybe the IACV is sticking some and needs cleaned. Or the connector is oxidized a tad and needs cleaned. There may be more than one thing happening, IDK.

I would have liked to have seen Rico's IACV changed by itself to see if that would have resolved his problem. But the dealer just changed out the entire Throttle Body. That is just too expensive of a thing to just try, unless under warrenty.

 

[Wisedrum]

For those, who have the same high idle problem as my 2013 CB has since a while, try out one thing. Before you stop, stay in a high gear and make the Honda run under 1.500 revs, then switch into neutral after doing so. My CB mostly returns after this treatment to a 1.0 50 rev idle. If I don't want it to stay in the high idlle revs, let' say in front of a red traffic light, it works wonders,. I know, this is not a solution for the problem, but can it make life a little easier with it until you find one. I'm still on my way and always be glad, if my CB right away idles normal without a trick, sometimes it does.

Wisedrum

 

[Lord Popgun]

I wonder if there could maybe be an issue with the plastic throttle body warping causing a binding of the IACV operation. Just throwing it out. I'm not taking mine off to see exactly how it works.

 

[curlyjoe]

I wonder if there could maybe be an issue with the plastic throttle body warping causing a binding of the IACV operation. Just throwing it out. I'm not taking mine off to see exactly how it works.

The throttle body is made out of plastic? Yeah, after taking a look at the '13 service manual, it looks like a big job to inspect/replace the IACV.

On page 5-6 of the '13 service manual, if idle rpm is too low, the IACV may be stuck closed. If idle speed is too high, the IACV could be stuck open. It seems a "sticky" IACV could be causing some of these problems.

kmoney was having problems with high idle speed and found that by unplugging the connector to the EOT sensor, the idle speed return to normal. However, I couldn't find any post by him to see if replacing the EOT sensor solved the problem.

 

[Riko_imp]

Again, not trying to minimize, trying to get a scope on how large the issue is.

We have a guy with 2200 miles on his bike without an issue, but he is wondering if it is something he should be concerned over.

Unfortunately we have no idea how many CB's are sold world wide or how many are affected. If it is 1% of units affected there is no need for concern... If it were 50% affected it would be like facing an epidemic of cholera or something. I have a feeling its more the former than the latter, but truthfully we just don't know.

Well, in that case, I would say not to be worried

I'd take the 'risk'

The IACV motor .. Is that part of the throttle body assy that Rico had replaced? or a separate part? Mechanical or electronic?

indeed, that part is located in the same area as the whole throttle body

if the whole throttle body would be replaced, the IACV would be included

Here's a wiki link that explains how the IACV works. Apparently the motor/valve can stick and thus cause idle control problems,

The same part is used on a lot of different Honda motorcycles (from 2007-2015) including all CB models in the states. [url=http://www.partzilla.com/parts/detail/honda/HP-16430-MFJ-D01.html]See link for list

If its the IACV, wouldn't also be a potential problem on all the other Honda bikes that use the same part? There is a 4P connector that plugs into the IACV so maybe corrosion could be more of a problem on the CB since it's a "naked" bike and thus exposed to the elements (including exuberant cleaning with a pressure washer) more than the other honda models.

So far I haven't had a problem with my '13 (16.5K miles).

to be honest, should not be happening and should never be an excuse nowadays

if I recall, some owners have also replaced this part alone, without succes

I wonder if there could maybe be an issue with the plastic throttle body warping causing a binding of the IACV operation. Just throwing it out. I'm not taking mine off to see exactly how it works.

The throttle body is made out of plastic? Yeah, after taking a look at the '13 service manual, it looks like a big job to inspect/replace the IACV.

On page 5-6 of the '13 service manual, if idle rpm is too low, the IACV may be stuck closed. If idle speed is too high, the IACV could be stuck open. It seems a "sticky" IACV could be causing some of these problems.

[URL=https://cb1100forum.net/threads/66155/]kmoney was having problems with high idle speed and found that by unplugging the connector to the EOT sensor, the idle speed return to normal. However, I couldn't find any post by him to see if replacing the EOT sensor solved the problem.

The throttle body is made out of plastic? Yeah, after taking a look at the '13 service manual, it looks like a big job to inspect/replace the IACV.

On page 5-6 of the '13 service manual, if idle rpm is too low, the IACV may be stuck closed. If idle speed is too high, the IACV could be stuck open. It seems a "sticky" IACV could be causing some of these problems.

[url=http://cb1100forum.com/forum/showthread.php?tid=9520&highlight=oil+temperature+sensor]kmoney was having problems with high idle speed and found that by unplugging the connector to the EOT sensor, the idle speed return to normal. However, I couldn't find any post by him to see if replacing the EOT sensor solved the problem.
IF the IACV is the root of the problem, (I say IF, because all we do here is again just guessing), than its not mechanical, because using the killswitch temporarily cures the issue...and thus has to be electronical. I would think.

Again, all assumptions, no facts.

 

[dave]

kmoney was having problems with high idle speed and found that by unplugging the connector to the EOT sensor, the idle speed return to normal. However, I couldn't find any post by him to see if replacing the EOT sensor solved the problem.
[/QUOTE]
My Dlx has experienced both high RPM (1,500) and low RPM / stalling - I have posted multiple times on this topic. Unplugging my EOT sensor makes the bike run better than new each and every time. I replaced the EOT sensor and this does NOT cure the problem.
Here's my latest update: My Dlx started with the low RPM / stalling. Condition came and went. Next it started with the high RPM (1,500), which comes and goes. It "seems" to be more prevalent when riding at low speed, and stop and go, 1st, 2nd gear around town riding. Put the bike in the garage when the condition occurs and the next time you ride it ( 1 - 5 days later) it runs fine. Unplugging my EOT sensor makes the bike run better than new. I put over 100 miles on my bike with the EOT unplugged and it ran great. Replacing the EOT sensor does NOT cure the problem - I did this. My low RPM / stalling condition disappeared, but was replaced by the high RPM idle problem. Unplugging the EOT sensor cures both the High RPM and Low RPM conditions - so it seems to me that this eliminates a "sticking" IACV. I tried disconnecting my battery to see if this would reset the computer and this did not help (I only disconnected it for less than 10 minutes though). I replaced my battery last month because it died and I "thought" my idle problem was cured with a new battery - it isn't. Bike ran better than new for first 150 miles. Spent yesterday riding around town, stop and go, 1st and 2nd gear. After about one hour the Low RPM / stalling condition returned - started stalling at every stop light. Brought the bike straight home and unplugged the EOT sensor and it immediately began running perfect again. Plugged the EOT sensor back in and the bike was idling fine - didn't have time to go for a test ride. Problem comes and goes at will. BTW - temperature was cool here, high of about 60 degrees F, so it definitely is NOT a over-heating problem. Please see my next post for additional information.