CB1100 Idle speed instability problem

[SportsterDoc]

Testing the IACV is described in the service manual pages 15-41 and 15-42, which are recapped in Post 775 of this thread

http://cb1100forum.com/forum/showthread....20&page=78

Fail safe operation of each sensor is described on page is 5-15 and 5–16 of the service manual, which are recapped in post 5 of this thread (already referenced by Max), see also posts 9, 11 & 22

[url=http://cb1100forum.com/forum/showthread.php?tid=12203&highlight=Dtc]http://cb1100forum.com/forum/showthread.php?tid=12203&highlight=Dtc

Max also listed the number of stepper motor pulses at start-up, etc.

This thread may also help

http://cb1100forum.com/forum/showthread....893&page=3

 

[Speed_imp]

Speed, you are in very good hands (Lord Popgun & Max :hello: ) , therefore, there is no need to interfere from my side.

@ Lord Popgun, have no longer access to scope due to C-19

Speed, just out of curiosity:
* do you have any related electronic or mechanical mods on your bike?
* I can not read the DTC's , would like to know why?, as this should be one first step. This procedure is outlined in HSM on p. 5-13 -MSC INFORMATION, and I believe you have this book.

Here is some more info/threads about idling issue:

Idle is high
IACV explained
IACV Replacement Tips
Bike Shut Off While Riding Today
How To Cure High Idle Issues (possibly)
SCANNER - aftermarket for CB
OBD Tool (OBD) - HealTech Electronics Ltd.
tps evaluating for ii issues
Idle problem resolved

No modification made on the bike

Yes I have the service manual but no blinking codes can be retrieved

 

[Speed_imp]

The side stand method you posted is right. Also, no one with the problem reported any fault light or codes stored.

How exactly did you connect the probes to the wires? I know, sounds like I don’t have a clue, but if I check mine I want it to be like you did it.

I would appreciate if you could check that signal in a known good working one! I check the two coils of the valve separatedly as I only have one probe (so only one channel). I back probe the connector with two needles and connect there my probe, something like this (here the TP sensor, for the IACV same procedure but pins 1-4 or 3-2):

I checked the valve as per manual 5-41 and 5-42 and everything looks good, so I just wanted to see what the ECU tells the valve to do. On start up we have a PWM like signal for about 3 seconds (Ignition ON, engine not working yet)

Once we start the engine we have pulses I guess to control the valve position (I have not counted the number of pulses)

But then, with engine at normal temperature, out of the cold start phase, "sometimes" when opening throttle from fully closed this PWM signal appears again for less than a second. While I don't have the PWM on opening throttle from closed position the idle runs fine, when it starts appearing the idle starts going down (heavy traffic conditions, throttle from fully closed to opening and so on).

And this is what makes no sense to me, together with the fact that the signal goes from 12V to -12V. Of course I just can replace the IACV and then check if it works as designed again but I would hate to do all the job and... I think there is a member with same symptoms and IACV replacement did not help.

So Lord Popgun if I just could have a reference signal from your bike which is working ok I could rule out one component or another and go for a ECM (if you have different signal behaviour) or IACV (if you find same pattern) replacement with almost 100% success probability. (The theory always looks great )

 

[Lord Popgun]

OK, I see how you did the test. I'll look this later today (I just got up )

Hopefully it is not an ECM as they are expensive. And changing the IACV is a pain. I think the first step is disassemble entire motorcycle!

I wish I had that analog scope though. I love analog scopes and their instant response times. A Tektronix analog scope and a Simpson 260 and I'm in Heaven!

Thanks for the test setup. I wondered if you back probed or made up a test harness. I can make one up as I have pins and connectors, but would rather not.

 

[Houtman_imp]

All of this is over my head but it is very nice to see that some Forum Members are able and willing to help ! THANKS to all.

 

[SportsterDoc]

Popgun wiill likely be your best help with the oscilliscope, but the issue is less likely to be the ECM pulses to the stepper motor.

The problem is most likely the IACV stepper not moving in direct relation to the pulses. It has no feedback, unlike a servo motor with an encoder, hence no associated DTC for position error.

Steppers are very accurate, within torque limits. Above torque limits, there is no certainity of proper movement for each pulse. Thus, if the IACV piston is not free to move, position will be off. Winding resistance may be within spec, but there is no diagnostic in the service manual for IACV piston free travel.

Tutorial: Stepper vs Servo

In 1984, I was a regional sales rep for power transmission eqipment (clutches, brakes, gear reducers, motors, chain, belts, etc.) One of the lines was Superior. I got into the industrial automation business by accepting an employment offer from a client. When I retired, 35 years later, Kollmorgen was the ultimate.

https://www.kollmorgen.com/sites/de...s/Old Stepper Catalog_Superior Electric_0.pdf

When I operated a motorcycle tuning shop in seventies and eighties, it was carbs and points, a few electronic ignitions (Martek 440 in my 1976 CB750); so most of my stepper/servo experience is industrial or automotive.

RFID-equipped workcell provides complete traceability

I retired Feb 2017, then Calmation closed May 2017, so website info is all gone.

 

[Lord Popgun]

I’m no expert on stepper motors Doc, but I sure agree with you. I’m setting up to look at the pulses but I really don’t think he has an ECM problem either.

It will be interesting to see what they look like. I have to dig out some needles now as the connector kit I have doesn’t have IACV connectors/pins. So no test harness.

 

[SportsterDoc]

I’m no expert on stepper motors Doc, but I sure agree with you. I’m setting up to look at the pulses but I really don’t think he has an ECM problem either.

It will be interesting to see what they look like. I have to dig out some needles now as the connector kit I have doesn’t have IACV connectors/pins. So no test harness.

Not discounting the potential for ECM irregularities, or harness connection issues, just trying to emphasize the likelihood of an IACV issue when the windings are in spec.

Much earlier in this thread, a couple forum members were arguing against the IACV being the issue, but the replacement by Dave in San Diego verifed the conclusion documented in this thread. Unfortunately, it is a pain to change.

Thanks to you, Max and Peter for the collaboration.

I may have gotten too personal in post 1047, but wanted newcomers to understand that I am not giving "I think so" advice.

When I was fairly new to this forum, I made the mistake of too much background and caught some flack for it:

Diagnostic Trouble Codes & Sensor testing

 

[dave]

what i have never been able to work out is how much the difference between the piston and the cyl housing actually is, maybe Dave has an idea, i never asked him back then.
[/QUOTE]
Hi Max. When I inspected my IACV upon removal the piston moved freely within the cylinder housing. If you remember, I even checked the movement of the old IACV versus the new IACV, and I didn't see any difference (checked by plugging it in to the bike normally and turning the ignition key off and on - while watching the piston movement with the IACV removed from the engine). My advice is just replace the IACV. By the way - replacing the IACV completely, 100% cured my idle instability issue, and it has never returned.

 

[SportsterDoc]

Dave
Thank you for your continued input.
Perhaps movement freedom was restricted when throttle body assembly was torqued into place?...and/or affected by thermal expansion?

Your bottom line advice is appreciated.

 

[Lord Popgun]

Doc, you know, we were just joking about the creds back then. Like we tend to do here.

Found the needles, have some jumpers ready and a long one for the proper ground so as to use 2 probes at once.

 

[SportsterDoc]

Doc, you know, we were just joking about the creds back then. Like we tend to do here.

Found the needles, have some jumpers ready and a long one for the proper ground so as to use 2 probes at once.

I know and we were still getting acquainted...and a couple times I probably overdid the background and appreciate Moderator deletion, at my request. At the risk of perhaps having to again do so, I will share this:

In 1985, I was asked for input on an automation project, for which I sold the DC motor, gear reducer and brake.

The machine, one of many built by Calmation's predecessor, inserted .025 square pins (bandolier fed) into an AT&T backplane at the rate of 20 pins per second: 5 pin head, dual heads, 2 insertions per second.

The challenge was to increase speed, but when motor speed was increased, the brake (sensor activated for positioning) would overheat and cause position drift. A larger brake would dissipate the heat, but created an inertia problem and advancing the timing of sensor activation was inconsistent.

My solution was not at all technical: I simply suggested blowing air on the brake to prevent overheating. It worked...and was not previously discussed in either Warner (electric clutch/brakes) nor Horton (pneumatic clutch/brakes) factory technical seminars.

The moral of this story is to recommend not overthinking a problem or its solution.
Correction
I forgot about DTC 29-1, which is most likely connector or wiring issue, not a positional error.
I would correct post 1042 and 1047 but too much time has elapsed for me to do so.

 

[Lord Popgun]

Well, first test. One probe on Bl/R and one on Bl/Y. Both probe ground leads connected to battery negative terminal.

Both traces show a square wave pulse train that comes up, then goes away. I am taking video’s and that I can email and someone can post them if they want. I AM NOT a videographer. I’m am using my iPhone on a stand. Due to test setup I can’t really watch the scope and reach the key. So, I start the video, turn on the key and wait for a response.

Interestingly, the pulse train does not appear until the fuel pump is done cycling. This is consistant every time I turn on the ignition. EDIT: not true. on the second run they showed up before the pump was done cycling.

The second run was interesting, but I messed with the scope and kinda messed up the video. So I’ll run it again in a while.

 

[Speed_imp]

Well, first test. One probe on Bl/R and one on Bl/Y. Both probe ground leads connected to battery negative terminal.

Both traces show a square wave pulse train that comes up, then goes away. I am taking video’s and that I can email and someone can post them if they want. I AM NOT a videographer. I’m am using my iPhone on a stand. Due to test setup I can’t really watch the scope and reach the key. So, I start the video, turn on the key and wait for a response.

Interestingly, the pulse train does not appear until the fuel pump is done cycling. This is consistant every time I turn on the ignition. EDIT: not true. on the second run they showed up before the pump was done cycling.

The second run was interesting, but I messed with the scope and kinda messed up the video. So I’ll run it again in a while.

There are two shocking things I did not expect in my case. The pulse train goes from - 12v to 12v (was expecting from 0v to 12v). On opening throttle from zero the pulse train appears again for less than a second, and this is what I don't understand. I put one end of the probe in Bl/Y and the other in Bl/O, in other words, measuring what the coil is receiving. I believe this pulse train on opening throttle is somehow screwing the position of my valve. If you want you can send the video to jose.maria.miranda.castillo@gmail.com so I can post it here with a youtube link!

 

[Lord Popgun]

Speed, I sent you a PM.

I want to send you the video. You can see the scope settings too. I used the same you had set. 10v, 25Ms/c (my scope won’t do 20)

I haven’t video’d a bike running yet. Getting ready to though.

 

[Cormanus]

Doc, you know, we were just joking about the creds back then. Like we tend to do here.

Found the needles, have some jumpers ready and a long one for the proper ground so as to use 2 probes at once.

I know and we were still getting acquainted...and a couple times I probably overdid the background and appreciate Moderator deletion, at my request. At the risk of perhaps having to again do so, I will share this:

In 1985, I was asked for input on an automation project, for which I sold the DC motor, gear reducer and brake.

The machine, one of many built by Calmation's predecessor, inserted .025 square pins (bandolier fed) into an AT&T backplane at the rate of 20 pins per second: 5 pin head, dual heads, 2 insertions per second.

The challenge was to increase speed, but when motor speed was increased, the brake (sensor activated for positioning) would overheat and cause position drift. A larger brake would dissipate the heat, but created an inertia problem and advancing the timing of sensor activation was inconsistent.

My solution was not at all technical: I simply suggested blowing air on the brake to prevent overheating. It worked...and was not previously discussed in either Warner (electric clutch/brakes) nor Horton (pneumatic clutch/brakes) factory technical seminars.

The moral of this story is to recommend not overthinking a problem or its solution.
Correction
I forgot about DTC 29-1, which is most likely connector or wiring issue, not a positional error.
I would correct post 1042 and 1047 but too much time has elapsed for me to do so.

Doc, What do you want the posts to say? Ferret or I will edit them for you.

 

[SportsterDoc]

Max posted this 17 Dec 2017 in postt 21 of "diagnostic trouble codes and sensor testing" thread:

Diagnostic Trouble Codes & Sensor testing

"Bonus footage; iacv operation on my bike, as usual a bit vague, the video editing program had trouble at 5% slow motion but what happens is ; on startup the iacv opens 65 steps and then closes 12 steps with a cold engine and 35 wiith a warm engine.

This happens in the blink of an eye as demonstrated at the very end of the video so i slowed it down to count the steps and direction, open and close.

the ecu does not know what position the iacv is at startup , so it always commands the valve open with 65 pulses, it then makes a decision to close x many steps based on the temperature of the eot sensor."

Doc, you know, we were just joking about the creds back then. Like we tend to do here.

Found the needles, have some jumpers ready and a long one for the proper ground so as to use 2 probes at once.

I know and we were still getting acquainted...and a couple times I probably overdid the background and appreciate Moderator deletion, at my request. At the risk of perhaps having to again do so, I will share this:

In 1985, I was asked for input on an automation project, for which I sold the DC motor, gear reducer and brake.

The machine, one of many built by Calmation's predecessor, inserted .025 square pins (bandolier fed) into an AT&T backplane at the rate of 20 pins per second: 5 pin head, dual heads, 2 insertions per second.

The challenge was to increase speed, but when motor speed was increased, the brake (sensor activated for positioning) would overheat and cause position drift. A larger brake would dissipate the heat, but created an inertia problem and advancing the timing of sensor activation was inconsistent.

My solution was not at all technical: I simply suggested blowing air on the brake to prevent overheating. It worked...and was not previously discussed in either Warner (electric clutch/brakes) nor Horton (pneumatic clutch/brakes) factory technical seminars.

The moral of this story is to recommend not overthinking a problem or its solution.
Correction
I forgot about DTC 29-1, which is most likely connector or wiring issue, not a positional error.
I would correct post 1042 and 1047 but too much time has elapsed for me to do so.

Doc, What do you want the posts to say? Ferret or I will edit them for you.

Doc, What do you want the posts to say? Ferret or I will edit them for you.
Thank you.
1042 Pls delete "I am not aware of a DTC for the IACV" there is one, DTC 29-1, but it is not related to position error.

1047 "It has no feedback, unlike a servo motor with an encoder, hence no associated DTC" add "FOR POSITION ERROR"

 

[Cormanus]

Done, Doc.

 

[Wisedrum]

Too bad, that a software update isn't allowed to fix the idle problem in the USA. Honda released it due to this problem and it totally cured this very annoying fault unexpensively for me without changing other parts of the bike, which more or less feels like fishing in the dark. The reason for a missfunction is to be seen in a not correct programming for the injection combined with the intake valves, a Honda dealer explained in my country after his treatment. This was that.

Wisedrum

 

[Speed_imp]

Too bad, that a software update isn't allowed to fix the idle problem in the USA. Honda released it due to this problem and it totally cured this very annoying fault unexpensively for me without changing other parts of the bike, which more or less feels like fishing in the dark. The reason for a missfunction is to be seen in a not correct programming for the injection combined with the intake valves, a Honda dealer explained in my country after his treatment. This was that.

Wisedrum

Good info! And good to try before starting with the work! A programming issue makes sense viewing the signals I am getting to the IACV. I will talk with my Honda dealer in Barcelona just in case they know about it. By the way, could you tell me your Honda dealer's name? Just in cause they are not aware here in Barcelona. Actually a couple of years ago they supposedly reflashed my ECU. Thanks!
In this video

Can be seen that a pulse train appears at the moment of opening throttle and after releasing idle speed is low again...
And in this other video the signal to IACV when idle speed is stable, normal operation. When opening throttle the pulse train does not appear...

Someone else thinks that my issue is related to the pulse train on opening throttle? This would explain why the issue worsens when in heavy traffic (closing and opening throttle slightly repeteadly)