IACV Replacement Tips

snackie_imp

First service completed
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Has anyone personally replaced the IACV on there CB1100? If so, any tips?
For instance, does the throttle body have to be taken out to do the job?

Thanks,

Bryan
 
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Peter,

Thank you so much. Looks like there's plenty of tips in those threads and, yes, I will do my best to troubleshoot the IACV before ripping the bike apart.

Best regards,

Bryan
 
snackie_imp said:
Peter,

Thank you so much. Looks like there's plenty of tips in those threads and, yes, I will do my best to troubleshoot the IACV before ripping the bike apart.

Best regards,

Bryan
No problem, this forum provides a lot of info, just to mention few names about this particular topic; Dave, Max, popgun, SportsterDoc + few more.... as said: study before working and good luck :thumbsup:
 
As he said, do study first. Its not an easy or quick job to get to the IACV.

First step in the manual: Disassemble rear half of motorcycle ;)
 
If my memory is good, there was Max??? post of faster approach by using modified Allen key ( but I am not 100% sure), so check it first:)
 
Yeah, we did go through that and it doesn’t work. You can’t get to it without removing the TB and that is a J.O.B.
 
Bryan none of us have the issue ourselves so we have to make best guesses but we learned a lot through Dave who did fix his iacv. there are two other members who have had success with this repair, it seems to only affect some 2014 models ( with some exeptions ) and we don't know why.
The iacv is a motorized air valve that regulates the amount of air to maintain 1050 rpm at idle, very much like opening the throttle slightly, it replaces the old school idle adjust screw and combines with the choke function and makes it automatic, it gets " stuck " at some point and gets worse over time.

Popgun is right, i thought i had found a shortcut but i was wrong, it did not work unfortunately.

The throttle body can stay where it is but the airbox needs to be removed towards the back so the tank, batterybox, rear fender etc have to be removed to gain access to the iacv which you need before all this is done, take lots of pictures so you know how things looked prior to removal.

Something that may work for you is disconnecting it when the bike behaves, is warmed up and idles at 1050 rpm, the piston inside will then stay open and doesn't move so the idle rpm stays around 1050 when warmed up, you need to remove the right hand plastic throttle body cover with the plastic screw and tilt it down to get access to the blue 4 pole connector, you squeeze the tab in the middle to unlock it and pull it out whilst the bike idles at 1050 rpm.

However you will get an orange check engine light blinking indicating a defect iacv code and may have to open the throttle a bit to get the engine to start initially but that may work ok in Hawaii because of the warm climate.
The c.e.l. light will stop when the connector is re-connected but the code remains in the memory and not visible unless it is in "service mode" and can then be erased by a sequence of the red service connector electrical wire link.
here is how to do this;
 
max, do you need the special bit of wire with a resistor or will any bit of wire work?
 
Any bit of wire will do the job as long as it can be inserted comfortably within the time limit, the dealer one uses a small switch i think but the size of the wire and the way it folded up was just convenient for me.

Playing with electronics i always have too many bits laying around and this one was nice in the way it folded making it easy to get in and out of the connector without splaying the pins open, automotive connectors are getting smaller, lighter and better in water resistance but a bit more fragile than spade or old fashioned bullit connectors.

And well done for pointing this out, it is probably a bit safer to use a resistor just in case the orange wire which carries 12 volts gets connected to the green earth wire by mistake but of course not every body have some resistors handy.
 
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Thanks everyone for your time and input.
So far, I have shorted the DLC by connecting the Brown and Green wires with a resistor. If I did it correctly, there were no stored codes. But, just to be sure, I have ordered the SCS connector.
I also warmed up the bike (without touching the throttle as this will increase the idle speed) then shut down the bike and removed the plug from the IACV motor. When I restarted the bike, it maintained a normal idle while pulling on the throttle. As soon as I reattached the plug to the IACV the idle shot back up to 1500 rpms.
Do you think it is safe to assume that the IACV motor is the culprit at this point or should I do further testing?
Thanks.
 
Sure looks like it Brian, apart from one member who found a twisted pin in the tps connector, had the same or similar idle issue and corrected it by looking at it very closely and then correctly re-inserted the pin in the connector, that may be worth a look in your case because it is easy to do, just make sure your tps cable is long enough so the connector does not get stressed when it is unplugged, you may have to take off the left tb plastic cover off to ease the cable out a bit.

all other cases have been solved by replacing the iacv, i do find it odd that the idle increased when the iacv was re connected, you observed something that we have not heard of before.

And like i mentioned before we don't know why the iacv misbehaves, it does not appear to be stuck or dirty, all we know is that if it is replaced the mysterious effect goes away and we have tried numerous things that could have had an influence on the idle rpm, none fixed it and replacing the iacv did!

The first confirmed case was Riko from Belgium, he had his entire throttle body replaced which is the recommended Honda cure and it did solve it completely, there were only two electrical parts on the tb, the tps and the iacv, so we eliminated the tps and the only thing left was the iacv to make a long story short.

It seems you are the type of guy that can handle this kind of job, it might be an idea to take some key pictures and do a brief description of what is involved so others can use this in the future.

Aloha and thanks for the precise feedback.
 
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Max,

The idle shot back up after I reattached the plug to the IACV and then pulled the throttle. What I have experienced is an increase in the idle speed AFTER the bike has warmed up and you pull the throttle. If you just start the bike and let it warm up, it will idle fine but as soon as you give it gas the idle begins to increase.
 
I'm glad you told me this Bryan, that makes a lot more sense, from your first account it seemed like an iacv setting was stored in memory and was executed right when it was connected, i can discard that idea now.

The iacv is doing a lot of work, every time the throttle is moved the iacv moves a few steps ( it's a stepper motor with two sets of windings and around 128 steps ) and stays in the last idle position when the ignition is switched off, it resets every time the bike is switched on and moves to it's startup position depending on the engine temperature, with the great help from popgun we figured out how this process works, the same iacv is used a lot on Honda's and sometimes fails.

Here is a video ( which did not upload as it should have but showing what roughly happens when it operates, again this one does not have the idle problem;

Thanks for the correction.
 
Hi Snackie. I was one of three or four forum members who have replaced their IACV. It looks like the guys have all got you started down the correct path, so I won't offer any additional advice except to comment that there are a GREAT bunch of very talented people on this forum who will help you (including me) if you any questions.
 
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Hi Dave,
Just wondering if my description of the problem is similar to what you experienced? How many miles did you have on your bike when the problem occurred and how many miles have you put on the bike since you replaced the IACV?

Thank you!
 
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UPDATE:
I bypassed the IACV (unplugged the motor) and it idles and runs fine. Think I'll do this until I get around to fixing it but I'm wondering what, if any, implications there may be. Any thoughts?

Thanks,

Snackie
 
I'm glad you did Bryan, other than the cel it should be ok ( anybody else ? ).
What you have here is nothing other than the equivalent of a manual idle adjustment screw and it should not change the behavior of the bike which would be some variation of " limp mode ".

Depending on which model and year unplugging of the tps caused the engine to have a " softer " character, it is very subtle but noticeable but i don't think unplugging the iacv has any influence on engine behavior, it will only warn you through the cel, if that bothers you, it may be that putting resistors ( 1 k ohm ) in place of the two coils will make the ecm happy again, worth a try in the longer run.

Thanks for the update, knowledge gained :thumbsup:
 
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