CB1100 Idle speed instability problem

[Cormanus]

Yeah ... good on you, max. Above and beyond, I'd say.

[Barkingshins_imp]

if you start at 19 minutes there is a surprise about getting the iacv out, i don't think we thought about this but it saves about two days work if i'm right, don't laugh!

Hi Max. Can you please save me the time of watching the video and say what the two day time savings is? Thank you.
Apparently a 1,700 mile road trip was just what the doctor ordered because the idle issue hasn't reared its head once since we hit the road on August 10th.

Brian. My high idle / low idle - stall condition came and left at will. Every time I thought something occurred to fix it (high speed running, change of gasoline brand, etc) it would come right back again. Good luck, and please keep us posted.

Good to know Dave. Thank you. I have a new IACV in-hand and will tackle the swap if/when the issue re-surfaces. Until then, I'm gonna blissfully pretend that it magically sorted itself.

[Hatred66_imp]

I'm afraid there are not many news about this issue. Just trying to keep this thread alive since I'm still suffering the low idling from time to time (mostly after longer rides in traffic or/and hot days). Does anyone have any updates on the different tests done? Anyone feels that the problem has gone away 100% after doing any of the proposed solutions? I'm 4 years out of warranty, so would love to know the ultimate solution for this (if it exists) before giving an expensive step to fix it. Too bad Honda has definitely decided to ignore the problem and the owners, never again...

Thanks everyone and gassssss!

[max]

Hi 66, we sometimes wonder if the problems have gone away/ repaired and forgotten to post feedback, there could well be some owners that have read the thread, done the repair and got on with life, that's fine too, we just got lucky with Dave ( and all others ) who has provided the necessary feedback because without which we were just stuck.

It also looks like it was a small number of faults and some have been remedied by other means, but after a long journey we concluded that the iacv replacement was the recommended fix.

Just a matter if the owner is capable of the swap ( around $100 for the part ) or go the dealer/friendly repair guy, sounds like a good out-of-season-repair.

[SportsterDoc]

Post 651 was a summary, 27 Dec 2017 and summarizes at least some of the testing that led Dave (San Diego) to replace his IACV and solve his idle problem.

There were issues other than the IACV, such as a damaged wire to a TPS or TPS issue, but to solve the issue and not unnecessarily replace the IACV, best to go through the tests (cleaning IACV port in D may not practical and I'd do E before D, saving the IACV for last).

Post 775 is a summary of why we (Max, Popgun, Peter and I) focused on the IACV.

Since it is the most pain of any sensor to change, we wanted to be fairly sure it was the culprit.

It does not seem to be a MAP issue, due to symptoms not matching.

It does not seem to be an EOT issue, per reports in this thread and symptoms not matching

It does not seem to be a TPS issue, due to the recent testing guided by Max. There may have been one or two TPS issues, but not for Dave.

Manual pages 5-74 and 5-75 cover IACV (symptoms seem to match)

Post 651 - Regarding popgun's post 619, referencing "BBS" issues on the Honda Rune Forum: Further research indicates that BBS is black exhaust smoke and fouled spark plugs from running too rich, which that forum has attributed to a TPS issue.

Suggestions if you experience low/high idle issues:

1. Check for active codes, per page 5-12 & 5-13 of the Factory Service Manual, checking the codes lists on pages 5-15 & 5-16

2. Check for stored codes, per pages 5-14 of the FSM

3. If no codes, then insure that there is no vacuum leak. An unlit propane torch applying propane to intake areas, engine at idle, will detect a leak by listening for a change in idle speed. Check vacuum hoses and fittings, one 4 way (17201-MCJ-003, $7) and one 5 way (17201-MCZ-003, $5.60), then snug all 8 clamps from throttle bodies to intake.

A. Disconnect Throttle Position Sensor connector (engine OFF), clean contacts (contact cleaner available at Home Depot or Lowes, etc.), check for damaged wiring and reconnect. GO FOR A RIDE. If issue persists, continue

B. Disconnect Idle Air Control Valve, clean contacts, check for damaged wiring and reconnect. GO FOR A RIDE. If issue persists, continue

C. Follow TPS diagnostics per pages 5-23 thru 5-25 of the FSM. Note comments in posts 615, 618 & 622, especially see Max's post 632 regarding TPS output test. If output is not 0.5 VDC, loosen fasteners (ignition on, engine NOT running) and rotate TPS to obtain 0.5 VDC, throttle closed. After adjusting TPS throttle closed output, do a throttle calibration with ignition on, engine NOT running, by SLOWLY opening and closing throttle, 2-3 times. GO FOR A RIDE. If issue persists, continue

D. Follow IACV diagnostics per pages 5-74 & 5-75 of the FSM. If OK, then remove IACV, clean IACV port and check for unobstructed travel. If not OK, IACV (16430-MJF-D01) is $119.13 from Honda. GO FOR A RIDE. If issue persists, continue

E. Follow EOT (Engine Oil Temperature Sensor) diagnostics per 5-21 of FSM, particularly resistance value of 2.4 to 2.9 Kohms (2,400 to 2,900 ohms) at 20C / 68 F. If not OK, EOT sensor (37750-KPH-701) is $34.56 from Honda. GO FOR A RIDE. If issue persists, re-check the FSM diagnostics. Note that a faulty ECM is a possibility, albeit rare. The only time I recall a failed ECM on a Sportster, was due to an internal 5 VDC sensor power supply failure.

The EOT (Engine Oil Temperature) sensor and IACV (idle Air Control Valve) are available from Honda. The Honda Rune Forum has posted a TPS replacement for the Keihin JT6H TPS: 16060-MBZ-A11, $114.29 from honda. This is for a 2006 CB600F. The Rune Forum posted that this sensor is a Keihin JT6H, but we have not yet verified compatibility

For non-USA owners, check that the latest ECM program is installed by your dealer.

[jwst11_imp]

Hi,

I am from Singapore and my 2014 CB1100 EX has low idling problem. I have replaced the IACV using back the same part number 16430-MFJ-D01. The low idling problem went away immediately but came back a few weeks later especially when riding in hot weather slow traffic condition. I noticed that 2017 CB1100 has a new IACV part number 16431-MGZ-D01.  Has anyone tried using 2017 IACV on 2014 CB1100 as I am hoping that the 2017 IACV can help to solve the low idling problem on the earlier CB1100?

[GoldOxide_imp]

Was this thread of any help? http://cb1100forum.com/forum/showthread....light=idle

[max]

Hi jwst, congrats on the iacv job, we have had one member who found a rotated ( twisted 90 degrees ) contact in his tps connector on the side of the throttle body and his problem was cleared after he re-aligned it correctly, just wanted to run that past you.

Have to wait for some of the others to check their part numbers but good to know there is a new part number available ( wonder why eh? ), and interesting the rpm's returned to normal instantly with the new iacv.

None of the assisting team has this issue so we have to rely on information from members like yourselves.

Can you tell us more about mileage at different stages of the problem?

[jwst11_imp]

Hi Max, thanks for your sharing on the rotated contact on tps connector. I didn't face this problem as I was following the service manual instructions closely when installing the new IACV. I have been doing mainly short distance commuting less than 10 km in each ride and my low idling problem started when my mileage was around 10,000 km. I have changed out the IACV at 15,000 km but low idling problem came back in less 500 km. I noticed that frequent gear changing and clutch lever movement in very slow moving traffic especially in hot weather will trigger the low idling problem. Maybe my CB1100 is telling me that she need more long distance rides!

[max]

Well you are the only one with a re-occurring isip, i would be inclined to go back to the place that sold you the replacement and ask for a new partnumber one no charge, we are doing Honda a favor by solving their problems for them.

500 odd k's seems a faulty part to me and it sounds like you know what you're doing on the bike.

We still don't know what is wrong with the part but we also have not measured the ohms resistance of the two stepper windings either at this stage and it may be a good idea to measure both of them, write it down and see what the resistance of the other part is, i will measure mine tomorrow and post the result, we may find a clue, who knows.

The iacv is in a hot place behind the cylinders and that may contribute to the fault, it works a bit every time the throttle operates from the stop and it seems it cannot overcome the force required to motivate the iacv piston and gets worse over time, also we could not find any soot deposits around the iacv piston, it was all very clean, was that the case with yours as well?

As a check it may be an idea to unplug the iacv and ride it like that for a short while to isolate the issue, the bike will respond with a softer character, but to fool the engine you can connect the old iacv temporarily and watch the response.......