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CB1100 Idle speed instability problem
Hi Beardy, great write-up. Hope your trip to the states goes well.

I requested that the dealer not reset the ECU until they had resolved the high idle condition through other means. I think the ECU reset is a temporary fix, and the condition returns after a couple of months (this occurred multiple times).

I hope the high idle condition does not return for you, but if it does, I recommend requesting the dealer not mask the condition with an ECU reset.
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(02-07-2017, 12:00 AM)johnf514_imp Wrote: Hi Beardy, great write-up. Hope your trip to the states goes well.

I requested that the dealer not reset the ECU until they had resolved the high idle condition through other means. I think the ECU reset is a temporary fix, and the condition returns after a couple of months (this occurred multiple times).

I hope the high idle condition does not return for you, but if it does, I recommend requesting the dealer not mask the condition with an ECU reset.

Thanks John,

Did your dealer install a newer/latest version of the software on your ECU, when they reset it? Don't suppose they gave you a slip of paper with the version No. or ID did they?

I tend to agree that they may just be writing a setting to the ECU to ignore a warning or voltage change from a faulty component. It's much cheaper and faster to re-write the ECU than to remove the Throttle Bodies and replace, say, the IACV. I'll try this fix out and report back. If the problem comes back then I'll investigate components.

I am a bit disappointed that Honda haven't released a bulletin, stating the fix and what they have changed. I don't like not knowing what the problem is! I know it shouldn't matter but I'd just like to know!! ;-))
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Something I don't understand, If the ICAV unit is the issue with the idle on some CB1100s, and that ICAV unit is used on many different Honda models, as previously stated, why have we not read about idle issues with those other models. There must be a million bikes around the globe running this unit. Confusing for me.
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(02-07-2017, 09:21 AM)The ferret_imp Wrote: Something I don't understand, If the ICAV unit is the issue with the idle on some CB1100s, and that ICAV unit is used on many different Honda models, as previously stated, why have we not read about idle issues with those other models. There must be a million bikes around the globe running this unit. Confusing for me.

Which is another way of saying maybe it is the ECU??
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It maybe!!
Could be the way the ECU interprets info is leading to the problem.

Could it be a faulty batch of ICAV's? Again maybe...

There seems to be a fair number of people in the Far East who've had the problem fixed with the re-flash.

Either way, component or ECU if it works, it works.... but I still would like to know why! ;-)

I might call Honda UK back and ask for some further info, they were really good when working out with the dealer why they couldn't upload the new software first time around.
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I'd like you know why as well, mainly because I'm curious about thingsand think everything can eventually be figured out logically..... and this one is driving me nuts.
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Beardy, the ECU was reset the first two times I took the bike into the dealership. As far as I know, there was no reflash of the software in the ECU.

Ferret, I agree with you that the IACV is used across millions of vehicles. It could be that a small batch of parts were faulty, and for some reason were unleashed on our bikes. For reference, my bike is a 01/2014 model.

It could very well also be the ECU, but I can state that in my experience, the first two resets of the ECU did not permanently cure the issue.
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I wonder if this IACV is used on any other air cooled motors? Maybe there is a difference in the temperatures the IACV is exposed to.
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(02-06-2017, 08:03 PM)beardyweirdy@me.com_imp Wrote: Hey All,

Just thought I'd let you know how I was going on with the on going Idle Prob.

I managed to get the bike back to the dealers yesterday and they successfully re-flashed the ECU with the latest Map from Honda. I'm not sure why it worked this time but I had called Honda UK to question what was going on and they offered the dealer some tech support and pos. a new disk/Software.

The dealer gave me a 'Honda ECM Update Report'. It states the previous ECUID which is 01019D0102
and an After the Update ECUID of 01019D0103. I don't know if this is specific to my bike or a general code for the re-flash.
There is also a note at the end of the report giving the code: 38770-MGC-D53_-M1.rwf.
I have no idea what that code refers to but it's the only other info on the report that isn't obvious stuff like date, VIN, milage etc....

After the re-flash I gave it a celebratory thrashing followed by a 30 min trawl thru London rush hour traffic, trying my best to emulate the riding style that had usually preceded the fault. It has mainly occurred when two up in town and dawdling. I was on my own yesterday but I road as tho I was carrying a pillion. I dragged the back brake to put the motor under load and slipped the clutch. I also sat in traffic and didn't cut thru and lane split so much as I would do with someone on the back.

I couldn't get it to show the fault. I let the revs fall to tick over and they stayed solid at 1050. Now I don't know if it will stay like that. We'll have to see what happens over the next week or so. I have a week or so at home so I'll be taking my girlfriend into work most days next week. That will give us a good test. But I'll keep my eye on it and report back.

On a side note, It has reset all the good things that Guhl Motors did to my ECU. I'm going to the USA on a work trip in a couple of weeks, so I'll take my ECU with me and get it re-done while I'm there.

I have spoken to Don at Guhl perviously and he's expecting the ECU. He said he'd go through it, work out what Honda had modified and then re-write their map to incorporate the Honda modifications.

I guess that way there is an option for you guys in the states to get the new map, via Guhl, if Honda USA isn't offering it to their customers.... if it works that is ;-)

It is interesting that the IACV replacement/overhaul seems to be working for some. I was going to test mine, as per the manual and see how it faired. Dave, did you run thru the diagnostic test in the manual? if so what did you find?

I'm not going to change anything else for a while tho, so I can really see if the new map is working for me .... Only change one thing at a time when testing and all that.

Which is another way of saying maybe it is the ECU?? The fact that unplugging my EOT sensor completely cures the idle problem (both high RPM and Low RPM / stalling) makes me believe it's the ECM, and not the IACV.
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Dave, the IACV checkout is in the fuel system section 5, page 5-41 in the '13/14 manual.
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