CB1100 Idle speed instability problem

[dsan1964_imp]

I also put some Lucas injector cleaner as most the day it was idling around 1400 rpm. When I got home I disconnected the battery. Started it up. It went back to Normal 1000... so I will ride all day tomorrow and see whats up. On the flip side I put a yosh slip on yesterday. I'm glad the idle issues started before I installed the yosh.or I may have thought it to be the cause. I have been riding more spirited. To see about magically getting it to idle normally , And also enjoying the new sound..


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[dsan1964_imp]

Started out pretty good hanging a little high then down to normal.... then back up to 1350 1400.. irritating...


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[MM300_imp]

I've watched this thread steadily growing over the last year never once thinking I'd have a reason to post in it.

Last weekend I took a short ride and noticed for the first time that the idle would not drop below 1500.

During the work week I read the full 30 plus pages of this thread and my takeaway was the following, (I'm long out of warranty): I'm not going to spend bucks on an experimental fix since there seems to be no consensus as to what the cause is. I did like what one poster said about doing a track day and I also liked the idea of trying injector cleaner. Well, I'm not going to the track, but I can get the fuel additive and take the bike on an early morning WFO flog session on a nearby super highway.

Stats going in:
Bought the DLX new in 2014.
Nothing has ever been modified.
The bike never presented one single problem.
I've done regular oil changes.
Had the 8K done at the selling dealer 11/2016.
The bike has 8700 miles on it.
It's only ever had 87 octane in it.
Original Battery is still in use.

I didn't have high hopes of curing the high idle issue but thought I'd take a shot anyway. So, out to the highway with a full tank of gas loaded with Lucas Fuel Injector cleaner. I blew half of the tank of gas out the tail pipe cycling up to full throttle and back down. Pinning it all the way open as much as I could. Prior to this I've never opened it all the way up and never went over 90 on the bike. I did what I did to make sure that any mechanical parts involved in fuel delivery were cycled stop to stop many times so that if it's gunk causing the high idle it might be moved or removed. What do I know?

After all that, it didn't work. It was fun though.

Got back to my house after several hours of doing that. Stopped at the top of my driveway and the motor was still spinning along at 1500. Oh well.

I let it sit for three hours till the motor was just barely warm. Started it up and the Idle settled right down to where it should be. Something it hadn't done over several rides in the last week. So I decided to ride to the store and for the first half of the ride, maybe four miles, at every stop, the idle settled right down. After that, at full operating temp, right back to 1500 again.

Into the store for a half hour, back to the bike, start it up, 1050 rpms, nice, half way home, back to 1500.

I guess this is what it's going to be now.

[Aka Tsubasa_imp]

What a bummer. Makes me sad. Wishing you luck.

[dsan1964_imp]

Now yesterday perfect idle all day. Intermittent problems... going flash the ECU. In near future...


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[Aka Tsubasa_imp]

If one really wanted to start digging into this they would piggyback a voltmeter to the IAC and see if the PCM is commanding an idle change just before it happens. If the PCM calls out the change as it happens then we could at least know that it a problem with engine mangement and not mechanical.

[PowerDubs_imp]

If one really wanted to start digging into this they would piggyback a voltmeter to the IAC and see if the PCM is commanding an idle change just before it happens. If the PCM calls out the change as it happens then we could at least know that it a problem with engine mangement and not mechanical.

What if the pcm sends voltage, and the mechanical part doesn't respond as it should....

[Aka Tsubasa_imp]

If one really wanted to start digging into this they would piggyback a voltmeter to the IAC and see if the PCM is commanding an idle change just before it happens. If the PCM calls out the change as it happens then we could at least know that it a problem with engine mangement and not mechanical.

What if the pcm sends voltage, and the mechanical part doesn't respond as it should....

What if the pcm sends voltage, and the mechanical part doesn't respond as it should....
One could perform a resistance check on the IAC but without having a voltage to idle speed table (assuming no other engine operating defects) there is no real way I know to verify proper IAC operation. I believe some fancy automoblies have IAC's that have position monitors but don't quote me on that.
Upon further thought if you see a voltage change and no idle speed change, replacement seems warranted.

[rustyski_imp]

I just experienced the engine die on my new to me 2014 DLX, cruising at 70 ish mph and the engine died.... I saw the check engine light. I started it with the switch on and off with speed going down and changing lanes (meeting guys at I 90 des plaines rest area) I held clutch and cruised it died again.
My post below before doing a 33 page back read lol

My post on a F B "Just got back from a 300 mi ride. I experienced a sudden engine cut off while cruising at 70 ish mph. I read on the CB 1100 forum about this issue. Has anyone encountered this issue? It did twice on me. The second one I did on purpose. Let me know. Thanks in advance. C.Thoughts. — in Chicago, Illinois.

[Cormanus]

I don't think we've ever heard this one rustyski. Mine died once at around 100kph, but it was because I'd inadvertently hit the kill switch.

You may have a fault in the kill switch.