The CB1100 Community Forum

(04-26-2018, 02:01 AM)pdedse_imp Wrote: [ -> ]

(04-26-2018, 01:32 AM)Magnus_imp Wrote: [ -> ]Dave,

If you run into any trouble I'm in San Diego as well and did the IACV a while ago as you probably know. I think I remember most of it. Sounds like you have a good hand on it and are taking it slow. But if you get truly stuck I'll be around this weekend. I could bring my CB so you can compare parts/wiring locations if you get lost. Eight Five Eight Nine 6 7 5 4 Eight 0

- John

I have to say, knowing of this just made my day--and I'm not even Dave.

I have to say, knowing of this just made my day--and I'm not even Dave.


Plus One !!!

Thanks magnus, i hope Dave will take you up on that offer, you can't beat experience and Dave--- deserves--- all the assistance he can get, very few guys are as persistent as he is and i can't prase his efforts enough.

If the piston is made out of plastic it may be affected by heat somehow.

Here is the spring in front of the piston;




___So does this mean that if the valve is not threaded down completely when it is installed (like mine was when I removed it) then the ECM will automatically compensate and send the proper signal to the motor to properly locate the valve?

Depending on the forces involved it may be a reason for failure, although not likely, think the spring may be part of damage control or the problem depending exactly what it's function is.

___So, then the fact that my valve was not threaded completely to the bottom of the threads when I removed it (the way it is supposed to be when installed) makes no difference? I was hoping that this was the root cause of my problem.

It may be that the shaft has moved on the bearings and mis-aligned itself somehow but that is just speculation from me, hence the question for pictures ( magnus? ) because once the iacv is mounted the comparison is no longer possible, we know the iacv fails sometimes, we don't know how though, here is your opportunity to find out, all we know is the pictures magnus posted regarding his iacv replacement.

Thing to remember is that the engine ran fine for a long time when you got it, if the piston was mis-aligned ( position-wise ) it would have shown up very quickly, so something has changed some time later.

Q; does the shaft rotate freely?

Two common methods of homing a stepper motor are:
1. Run to limit/end of travel switch
2. Monitor current, which will increase if run to a hard stop (see link)
http://www.orientalmotor.com/stepper-mot...oming.html

My experience is limited to industrial applications, hence the above link.

I do not know which method Honda employs.

With a 4 wire connection,1 is possible.

The schematic shows
IACV1A to ECM A6 (black/yellow)
IACV1B to ECM A7 (black/red)
IACV2A to ECM A17 (black/blue)
IACV2B to ECM A16 (black/orange)

Both circuits (black/yellow to black/red and black/blue to black/orange) have the same resistance parameters of 91-121 ohms at 77 F, so I am thinking 1 is not as likely as 2.

Does the FSM advise anything further (other than info on FSM pages 5-74, 5-75, 15-41 & 15-42)?

In possibility 1, if the switch has moved, damaged, etc., true home would be lost.
In possibility 2, if there is binding, there could be a premature higher current read.

Both of these could occur even if the stepper motor is functioning normal.

(04-26-2018, 01:32 AM)Magnus_imp Wrote: [ -> ]Dave,

If you run into any trouble I'm in San Diego as well and did the IACV a while ago as you probably know. I think I remember most of it. Sounds like you have a good hand on it and are taking it slow. But if you get truly stuck I'll be around this weekend. I could bring my CB so you can compare parts/wiring locations if you get lost. Eight Five Eight Nine 6 7 5 4 Eight 0

- John

My hat is off to you, John!
Kudos for the offer.
Dave
Did you find any carbon/crud/partial blockage in the port controlled by the IACV?

First off, my sincere thank you to John for his very generous offer. Hopefully I will not have to call you, but it's nice to know that help is not far away. John - did you remove your rear wheel to get the fender out? Did you remove the entre throttle body assembly?

I reinstalled the battery last night and tested the old and new IACVs side-by-side. I must have cycled each one thirty times, alternating back and forth. In all honesty, I cannot detect any difference in the way they operate. But this test only checks what I believe to be only a small portion of the full operation of the IACV; I'm sure you guys who are much more knowledgeable on this topic would know how to perform a more thorough inspection.

The valve is metallic, so I assume it is aluminum. The port in the cylinder is completely clean and there is no obstruction.

My plan is to get the new IACV installed tomorrow. I will perform a valve clearance inspection while I have the tank off, but I don't know if I'll have time tomorrow to do all of this (other chores and responsibilities are calling).

Thanks again to all you guys for all of your support!

The FSM may not so mention, but I would be tempted to spray silicone lubricant on the IACV piston before installing.

Good luck, Dave. I will be off-line tomorrow (going to Laughlin, via Kingman and Oatman) but will log-on as soon as I get home, as I am anxious to know of your progress.

(04-27-2018, 01:30 AM)SportsterDoc_imp Wrote: [ -> ]The FSM may not so mention, but I would be tempted to spray silicone lubricant on the IACV piston before installing.

Good luck, Dave. I will be off-line tomorrow (going to Laughlin, via Kingman and Oatman) but will log-on as soon as I get home, as I am anxious to know of your progress.

Thank you Doc. I do not believe our bikes have a travel limit sensor switch, so your second option of measuring the current is probably how Honda does it. Maybe my valve got stuck at one time and this caused a higher than normal current flow that somehow disrupted the calibration (if there is a calibration) between the valve and the ECM?

I believe the FSM states to coat the valve with engine oil before installing it. What do you think about a very lite coat of grease? Would the grease potentially cause too much friction?

I didn't have to remove the rear wheel. I kept the throttle body assembly attached. I think I posted a picture somewhere in this long, long thread.

(04-26-2018, 11:46 PM)Dave_imp Wrote: [ -> ]First off, my sincere thank you to John for his very generous offer. Hopefully I will not have to call you, but it's nice to know that help is not far away. John - did you remove your rear wheel to get the fender out? Did you remove the entre throttle body assembly?

I reinstalled the battery last night and tested the old and new IACVs side-by-side. I must have cycled each one thirty times, alternating back and forth. In all honesty, I cannot detect any difference in the way they operate. But this test only checks what I believe to be only a small portion of the full operation of the IACV; I'm sure you guys who are much more knowledgeable on this topic would know how to perform a more thorough inspection.

The valve is metallic, so I assume it is aluminum. The port in the cylinder is completely clean and there is no obstruction.

My plan is to get the new IACV installed tomorrow. I will perform a valve clearance inspection while I have the tank off, but I don't know if I'll have time tomorrow to do all of this (other chores and responsibilities are calling).

Thanks again to all you guys for all of your support!

And here is Magnus’ post with the pic: http://cb1100forum.com/forum/showthread....#pid166655

(04-27-2018, 03:37 AM)Dave_imp Wrote: [ -> ]

(04-27-2018, 01:30 AM)SportsterDoc_imp Wrote: [ -> ]The FSM may not so mention, but I would be tempted to spray silicone lubricant on the IACV piston before installing.

Good luck, Dave. I will be off-line tomorrow (going to Laughlin, via Kingman and Oatman) but will log-on as soon as I get home, as I am anxious to know of your progress.

Thank you Doc. I do not believe our bikes have a travel limit sensor switch, so your second option of measuring the current is probably how Honda does it. Maybe my valve got stuck at one time and this caused a higher than normal current flow that somehow disrupted the calibration (if there is a calibration) between the valve and the ECM?

I believe the FSM states to coat the valve with engine oil before installing it. What do you think about a very lite coat of grease? Would the grease potentially cause too much friction?

If it homes via current sensing, then getting stuck would give false feedback to the ECM. The ECM would think it did a full travel, instead of a partial travel, but we are just guessing, without knowing more about the actual ECM program.

The 4 wire, with two equal resistance circuits, indicate that the IACV uses two phase bi-polar windings: https://learn.adafruit.com/all-about-ste...-steppers.

(04-27-2018, 03:37 AM)Dave_imp Wrote: [ -> ]

(04-27-2018, 01:30 AM)SportsterDoc_imp Wrote: [ -> ]The FSM may not so mention, but I would be tempted to spray silicone lubricant on the IACV piston before installing.

Good luck, Dave. I will be off-line tomorrow (going to Laughlin, via Kingman and Oatman) but will log-on as soon as I get home, as I am anxious to know of your progress.

Thank you Doc. I do not believe our bikes have a travel limit sensor switch, so your second option of measuring the current is probably how Honda does it. Maybe my valve got stuck at one time and this caused a higher than normal current flow that somehow disrupted the calibration (if there is a calibration) between the valve and the ECM?

I believe the FSM states to coat the valve with engine oil before installing it. What do you think about a very lite coat of grease? Would the grease potentially cause too much friction?

Grease may be too low viscosity and my thinking is that silicone spray lubricant may last longer. Do as you are most comfortable. If silicone, then check material compatibility...some is fine with plastics, rubber, etc....some are not.

Thanks for the link popgun, looks pristene inside that throttle body.
That is something i had not considered doc, current sensing.
I think that can be simulated by holding the shaft and see if it the ecm stops prematurely on over current.

Something else that crossed my mind is; what would happen if two of the wires are reversed somehow?
remember some tail lights have the green and pink/blue wires the wrong way.
It may be a good idea to check the color of the wires in the 4 pole iacv connector and at the ecm if they are the right way around.

on the ecm;
black/yellow---a6----iacv1a
black/orange--a7----iacv2a
black/blue------a16--iacv1b
black/red--------a17--iacv2b

and on the iacv connector in the following order;
black/yellow
black/red
black/blue
black/orange

You can see that the inside pair is coil b and outside pair is coil a on the iacv.

It may well be that one side of the coils is connected to dc volts or ground and can be measured with a voltmeter for correct polarity at the disconnected iacv connector ( at any time ).

link for wiring diagram http://cb1100forum.com/forum/showthread....#pid199015 and click on " here " at bottom of post.


Dave may know how much torque is produced by the stepper motor and if the shaft can rotate freely or is held in place if not energized?

If it was me i would not apply grease on the piston, dust may stick to it over time and probably too much friction inside the barrel when cold.
as far as i can tell it only makes contact in the groove of the piston so maybe a tiny amount of oil inside that groove only, remember it gets hot in there and any excess would run off, collect at the bottom of the barrel and just sit there collecting filtered dust.

And thanks for the check of the piston material Dave, when the iacv initialises does it move the piston away from the stepper motor ( out ) and then reverse toward it or the other way round?

At the end of the day Dave will have the only faulty iacv in captivity in the world.