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CB1100 Idle speed instability problem
(03-08-2018, 08:40 AM)kennyw_imp Wrote: My bike is only having the issue in hot weather (90F+) combined with stop and go traffic. Not a single problem since last August though. Last August is also the first time I experienced the symptoms to the extent of the bike dieing.

I'm willing to bet my case is wear or corrosion starting to affect the performance of something rather than defective parts from the factory.

I park indoors at home and outdoors at work. I ride in all weather conditions except snow. My bike gets washed twice a year, if it needs it or not.

Have you checked connections of TPS, EOT and IACV?
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(03-07-2018, 08:37 PM)max_imp Wrote: Hi Mech, looking at your part of the spreadsheet i assume that is the video you refer to ( correct me if i am wrong at any stage ).

So the engine is cold, started and idling at 1500 rpm as they normally do, but when you pull the clutch in it idles at 1700 rpm instead,unless the lever is pulled close to the handle and drops back to 1500 rpm ( had to read your explanation 6 times and i think this is what you mean ).

It is possible that because of the cold temperature the engine idles at 1700 instead of 1500 rpm.

Just checked and the switch on the clutch is open when the lever is forward, and closes if the lever is pulled back, you can hear when it operates.
The wiring is hard wired ( not dependant on the elecrtonic control module ) but does provide input TO the ecm.
That means the clutch, neutral and sidestand work to prevent starting even if the ecm is faulty.
The inputs to the ecm are; b22 sstand and b33 nl sw.

To verify if it is the switch you can pull one connector off and confirm the switch is causing the change in rpm.

here is the diagram courtesy of popgun





Question is; has it always been like this in below 55 degrees or is this new behaviour that started with low idle, my guess is it is not related but who knows.

Interesting about the warmup period of 4 miles, do the rpm's gradually lower when the engine heats up or is there a sudden drop and when does the low idle start?

Thanks for checking the clamps.


Well, when I first got the bike I was reading about the issues and was thinking “ glad this isn’t happening to me”... but around 5 or 6 thousand miles on the bike it started.

Actually the opposite of what you read the 6 times...sorry for that. It will cold idle at around 1500 rpm but will increase to 1700 rpm when clutch lever is being released. Clutch is right at the point of grabbing but still no load on the engine. It acts as if I were twisting the throttle as I was letting out the clutch.

As for the warm up, the idle will go down after a mile or so but the idle will still increase when letting out the clutch for four miles or about 10 minutes. There really isn’t a sudden drop , it gradually goes down to 1000 as I ride for a while. I do have a video of when I started it before work this morning (not very cold) but need to get a better one, I will try to load it on YouTube and post a link.
(03-06-2018, 07:33 PM)max_imp Wrote: Thanks Mechanix, there seems to be a relation ship with higher temperatures, not clear why for now but you are not the first to link the ii issue to warm conditions.

Could you explain in more detail what happens when the clutch is engaged? is the engine warmed up, does it happen consistently, does the idle return when the clutch is released etc.

It would help your case if you could document the situation with appropriate comment on the video and show them what happens and how often it occurs, even better post it on youtube so everybody can see it, also get some sort of proof that you made the dealer aware of this idle behaviour ( witness ) and when before the warranty runs out, according to my nz dealer Honda do stand behind their product even after the warranty expires but require strong proof to do so.

max

Link to cold idle
https://youtu.be/ic9QxN_SEMU

Link to warm day ride low idle
https://youtu.be/_PnA_x66VVM
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Thanks Mech, nice video's and very surprising action on the clutch, from the video it is not clear if the switch is operating to cause the increased rpm effect, is it possible to disconnect the switch and see if any change occurs?

And has this behaviour started at the same time the low idle started?

Thanks for posting the video's they are perfect for us to work with as we are mostly in the dark about the exact behaviour since none of our team actually have the issue ourselves.

max
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(03-08-2018, 11:15 AM)SportsterDoc_imp Wrote:
(03-08-2018, 08:40 AM)kennyw_imp Wrote: My bike is only having the issue in hot weather (90F+) combined with stop and go traffic. Not a single problem since last August though. Last August is also the first time I experienced the symptoms to the extent of the bike dieing.

I'm willing to bet my case is wear or corrosion starting to affect the performance of something rather than defective parts from the factory.

I park indoors at home and outdoors at work. I ride in all weather conditions except snow. My bike gets washed twice a year, if it needs it or not.

Have you checked connections of TPS, EOT and IACV?
I have done no troubleshooting yet. I need to wait for warmer weather when I can recreate the issue to verify it gets fixed.
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(03-08-2018, 07:14 PM)max_imp Wrote: Thanks Mech, nice video's and very surprising action on the clutch, from the video it is not clear if the switch is operating to cause the increased rpm effect, is it possible to disconnect the switch and see if any change occurs?

And has this behaviour started at the same time the low idle started?

Thanks for posting the video's they are perfect for us to work with as we are mostly in the dark about the exact behaviour since none of our team actually have the issue ourselves.

max

Ok, this morning was a bit cool so I started the bike and had it in neutral, no issue. Put bike in gear and had idle at 1200rpm until I began to let out the clutch lever...up to 1700rpm. I shut off the bike and disconnected the clutch switch, restarted bike and cold idle was 2000rpm. A few twists of the throttle and idle rpm still at 2000 and no reaction with clutch. I had to leave for work so no video to post but I will try this again on another cool morning and start off recording.
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I am at a loss to attempt to explain any electrical correlation with releasing the clutch and increased idle speed; other than perhaps the IACV is reacting/over-reacting to increased load?

Before pursuing this, Is it possible that there is zero slack in the throttle cable and your right hand moves slightly as left releases? Have you tried this with hand off throttle? (could not see with vertical video format)

Ambient temperature might possibly affect electrical connections or a vacuum loss.

The EOT (engine oil temperature) sensor is a thermistor. It is very high resistance when coldest, then loses resistance as the temperature increases.

Therefore, if there is a poor/high resistance connection relating to the EOT, the higher resistance could indicate to the ECM a colder operating temperature than actual. If so, the IACV would maintain higher RPMs, as during warm-up.

Even though the IACV operation is a prime suspect in most of the reported idle issues, there may be (instead of or in addition to) poor electrical connection(s).
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(03-09-2018, 03:31 PM)SportsterDoc_imp Wrote: I am at a loss to attempt to explain any electrical correlation with releasing the clutch and increased idle speed; other than perhaps the IACV is reacting/over-reacting to increased load?

Before pursuing this, Is it possible that there is zero slack in the throttle cable and your right hand moves slightly as left releases? Have you tried this with hand off throttle? (could not see with vertical video format)

Ambient temperature might possibly affect electrical connections or a vacuum loss.

The EOT (engine oil temperature) sensor is a thermistor. It is very high resistance when coldest, then loses resistance as the temperature increases.

Therefore, if there is a poor/high resistance connection relating to the EOT, the higher resistance could indicate to the ECM a colder operating temperature than actual. If so, the IACV would maintain higher RPMs, as during warm-up.

Even though the IACV operation is a prime suspect in most of the reported idle issues, there may be (instead of or in addition to) poor electrical connection(s).


I knew I should have taken a better video! Left hand on the clutch lever and right hand taking video so no throttle contact. And I know it is hard to tell but I was not on the brakes at all and clutch was right at the point of starting to grab but no load on the engine, the bike didn’t even try to move.

I will go through all the connections on a day off of work but I will also try to look at everything else I can get to quickly without taking the bike out of operation...it’s my primary vehicle right now.

I really appreciate all the input I have been reading in regards to this, this is one of the best groups I have been a part of.
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Mechanix i think your video's are very educational but the next one can be a bit better and longer, good idea and very good of you to recognize this.

What i also wonder is if the clutch effect works in all gears and neutral or just 1st gear ( both with connected and disconnected switch ) you could comment this in the video.
I suspect this behaviour is possibly programmed into the ecm hence the gear test.

You are doing great, we can come up with enough hints to narrow this down quite a bit but we need your help and i will try to explain why things happen the way they do along the way.

cheers max
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Update: I am performing the four, wire connection inspection and cleaning steps recommended my Max, one at a time. I started with the IACV connection and here are my comments: Connection appeared clean and in perfect condition. I thoroughly sprayed the connectors with electrical connection cleaner and dried with compressed air. I then started the bike with the IACV disconnected to see what would happen. The bike had not been started in several days, but started quickly, and immediately went into an 1,100 RPM idle, which is surprising because it normally goes into a high (1,400 – 1,500 RPM) idle when the engine is cold. This idle speed lasted for maybe 5 seconds, or less, and then dropped to about 600 RPM. I believe it would have stalled, but I blipped the throttle a few times to see what would happen. Each time the idle speed returned to about 600 RPM, and I am sure the engine would have stalled had I not twisted the throttle. I reconnected the IACV and went for a ride. Within three miles the low idle condition returned, so the conclusion of this test is that cleaning the IACV connection does not cure the low RPM idle condition. I will continue testing today by disconnecting and cleaning the remaining three connections recommended by Max, and will report back (as soon as I complete rebuilding and installing the VFR800 forks).
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(03-10-2018, 01:26 AM)Dave_imp Wrote: Update: I am performing the four, wire connection inspection and cleaning steps recommended my Max, one at a time. I started with the IACV connection and here are my comments: Connection appeared clean and in perfect condition. I thoroughly sprayed the connectors with electrical connection cleaner and dried with compressed air. I then started the bike with the IACV disconnected to see what would happen. The bike had not been started in several days, but started quickly, and immediately went into an 1,100 RPM idle, which is surprising because it normally goes into a high (1,400 – 1,500 RPM) idle when the engine is cold. This idle speed lasted for maybe 5 seconds, or less, and then dropped to about 600 RPM. I believe it would have stalled, but I blipped the throttle a few times to see what would happen. Each time the idle speed returned to about 600 RPM, and I am sure the engine would have stalled had I not twisted the throttle. I reconnected the IACV and went for a ride. Within three miles the low idle condition returned, so the conclusion of this test is that cleaning the IACV connection does not cure the low RPM idle condition. I will continue testing today by disconnecting and cleaning the remaining three connections recommended by Max, and will report back (as soon as I complete rebuilding and installing the VFR800 forks).

Dave, thank you for faithfully continuing with the regimen and continuing to report.
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