CB1100 Idle speed instability problem

[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 .

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 [url=http://cb1100forum.com/forum/showthread.php?tid=17651]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

[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: [url=https://www.bikebandit.com/oem-parts/detail/honda/16430-mfj-d01/b1649067?m=155484&sch=793046]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

https://cb1100forum.com/forum/showthread...#pid309372

[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.