CB1100 Idle speed instability problem

[SportsterDoc]

Summary, to date:

Regarding popgun's post 619, referencing "BBS" issues on the Honda Rune Forum: Further research indicates that BBS is black exhaust smoke and fouled spark plugs from running too rich, which that forum has attributed to a TPS issue.

Suggestions if you experience low/high idle issues:

1. Check for active codes, per page 5-12 & 5-13 of the Factory Service Manual, checking the codes lists on pages 5-15 & 5-16

2. Check for stored codes, per pages 5-14 of the FSM

3. If no codes, then insure that there is no vacuum leak. An unlit propane torch applying propane to intake areas, engine at idle, will detect a leak by listening for a change in idle speed. Check vacuum hoses and fittings, one 4 way (17201-MCJ-003, $7) and one 5 way (17201-MCZ-003, $5.60), then snug all 8 clamps from throttle bodies to intake.

A. Disconnect Throttle Position Sensor connector (engine OFF), clean contacts (contact cleaner available at Home Depot or Lowes, etc.), check for damaged wiring and reconnect. GO FOR A RIDE. If issue persists, continue

B. Disconnect Idle Air Control Valve, clean contacts, check for damaged wiring and reconnect. GO FOR A RIDE. If issue persists, continue

C. Follow TPS diagnostics per pages 5-23 thru 5-25 of the FSM. Note comments in posts 615, 618 & 622, especially see Max's post 632 regarding TPS output test. If output is not 0.5 VDC, loosen fasteners (ignition on, engine NOT running) and rotate TPS to obtain 0.5 VDC, throttle closed. After adjusting TPS throttle closed output, do a throttle calibration with ignition on, engine NOT running, by SLOWLY opening and closing throttle, 2-3 times. GO FOR A RIDE. If issue persists, continue

D. Follow IACV diagnostics per pages 5-74 & 5-75 of the FSM. If OK, then remove IACV, clean IACV port and check for unobstructed travel. If not OK, IACV (16430-MJF-D01) is $119.13 from Honda. GO FOR A RIDE. If issue persists, continue

E. Follow EOT (Engine Oil Temperature Sensor) diagnostics per 5-21 of FSM, particularly resistance value of 2.4 to 2.9 Kohms (2,400 to 2,900 ohms) at 20C / 68 F. If not OK, EOT sensor (37750-KPH-701) is $34.56 from Honda. GO FOR A RIDE. If issue persists, re-check the FSM diagnostics. Note that a faulty ECM is a possibility, albeit rare. The only time I recall a failed ECM on a Sportster, was due to an internal 5 VDC sensor power supply failure.

The EOT (Engine Oil Temperature) sensor and IACV (idle Air Control Valve) are available from Honda. The Honda Rune Forum has posted a TPS replacement for the Keihin JT6H TPS: 16060-MBZ-A11, $114.29 from honda. This is for a 2006 CB600F. The Rune Forum posted that this sensor is a Keihin JT6H, but we have not yet verified compatibility

For non-USA owners, check that the latest ECM program is installed by your dealer.

[Cormanus]

Thanks to you all for the ongoing work on this issue that has flummoxed a number of members.

Has anyone yet tested for a vacuum leak? If so, what was the result?

[postoak_imp]

SporsterDoc - what about the posters from other countries who had ECU updates that fixed the problem? If that update is available in the U.S, I would think that would be one of the first actions to take.

[736cc_imp]

Rumor has it USA Honda not updating the ecu due to costly E.P.A. re-certifications, but it’s just a rumor

[SportsterDoc]

SporsterDoc - what about the posters from other countries who had ECU updates that fixed the problem? If that update is available in the U.S, I would think that would be one of the first actions to take.

1. An ECM reflash may only cure some of the issues. It would not correct a loose connection, failed/failing sensor or vacuum leak. There certainly seems to be more than one cause. Also, if the tech doing the reflash also checked the wiring, that may have solved the issue before the reflash.

2. There is no indication, at this time, of an updated ECM program for the USA...even for states not on the left coast.

Rumor has it USA Honda not updating the ecu due to costly E.P.A. re-certifications, but it’s just a rumor

Rumor or no, it is a very likely supposition!

This is my third EFI bike:

The 2012 Triumph Bonneville was prepped with an ECM tune for an Arrow aftermarket exhaust...even though I kept it stock,then later center drilling the mufflers 1/2" to be audible. It ran very well, under all conditions. The factory tune may have caused some hesitation.

The 2016 Moto Guzzi V7II has a new ECM program download at 600 miles, which only slightly helped cold and hot starts. The hot starts were the most irritating. It could be heat saturated, stop to go into a store for 15-30 minutes and it would bog if not allowed to idle for 1/2 a minute. I was suspecting the heated O2 sensors having to re-warm...just a guess. Might have been curable, but an altercation with the dealership owner ended that.

This 2014 CB1100 is flawless...cold or hot. Don't think I want the ECM touched!

Thanks to you all for the ongoing work on this issue that has flummoxed a number of members.

Has anyone yet tested for a vacuum leak? If so, what was the result?

Hopefully members are not shy about snugging 8 hose clamps!
Maybe just shy about reporting it?!

Just got back from a ride along Lake Mead up to Overton.
It was a relaxed day.
59.9 MPG going up North Shore at 55 MPH (elevation gain)
60.3 MPG returning via Interstate 15 at 65 MPH (75 MPH zone).
Can't believe I had the patience, but was determined to not give in to bursts of speed!

In the garage, bike went up on centerstand for chain lube (2358 miles)
Not finding any fasteners which needed torquing.
Got into the habit after riding Sportsters and started preaching post-ride inspection.

[pdedse]

SporsterDoc - what about the posters from other countries who had ECU updates that fixed the problem? If that update is available in the U.S, I would think that would be one of the first actions to take.

1. An ECM reflash may only cure some of the issues. It would not correct a loose connection, failed/failing sensor or vacuum leak. There certainly seems to be more than one cause. Also, if the tech doing the reflash also checked the wiring, that may have solved the issue before the reflash.

2. There is no indication, at this time, of an updated ECM program for the USA...even for states not on the left coast.

Rumor has it USA Honda not updating the ecu due to costly E.P.A. re-certifications, but it’s just a rumor

Rumor or no, it is a very likely supposition!

This is my third EFI bike:

The 2012 Triumph Bonneville was prepped with an ECM tune for an Arrow aftermarket exhaust...even though I kept it stock,then later center drilling the mufflers 1/2" to be audible. It ran very well, under all conditions. The factory tune may have caused some hesitation.

The 2016 Moto Guzzi V7II has a new ECM program download at 600 miles, which only slightly helped cold and hot starts. The hot starts were the most irritating. It could be heat saturated, stop to go into a store for 15-30 minutes and it would bog if not allowed to idle for 1/2 a minute. I was suspecting the heated O2 sensors having to re-warm...just a guess. Might have been curable, but an altercation with the dealership owner ended that.

This 2014 CB1100 is flawless...cold or hot. Don't think I want the ECM touched!

Thanks to you all for the ongoing work on this issue that has flummoxed a number of members.

Has anyone yet tested for a vacuum leak? If so, what was the result?

Hopefully members are not shy about snugging 8 hose clamps!
Maybe just shy about reporting it?!

Just got back from a ride along Lake Mead up to Overton.
It was a relaxed day.
59.9 MPG going up North Shore at 55 MPH (elevation gain)
60.3 MPG returning via Interstate 15 at 65 MPH (75 MPH zone).
Can't believe I had the patience, but was determined to not give in to bursts of speed!

In the garage, bike went up on centerstand for chain lube (2358 miles)
Not finding any fasteners which needed torquing.
Got into the habit after riding Sportsters and started preaching post-ride inspection.

I find it interesting that some get that kind of mileage on their CB1100. Normal for me was 43mpg, some city, but mostly 45-60 country riding...maybe 49-50 if all hiway. And I don't ride crazy on the throttle.

I've wondered if there might be a correlation between bikes with high/low idle issue and overall lower mpg for those bikes affected.

[SportsterDoc]

SporsterDoc - what about the posters from other countries who had ECU updates that fixed the problem? If that update is available in the U.S, I would think that would be one of the first actions to take.

1. An ECM reflash may only cure some of the issues. It would not correct a loose connection, failed/failing sensor or vacuum leak. There certainly seems to be more than one cause. Also, if the tech doing the reflash also checked the wiring, that may have solved the issue before the reflash.

2. There is no indication, at this time, of an updated ECM program for the USA...even for states not on the left coast.

Rumor has it USA Honda not updating the ecu due to costly E.P.A. re-certifications, but it’s just a rumor

Rumor or no, it is a very likely supposition!

This is my third EFI bike:

The 2012 Triumph Bonneville was prepped with an ECM tune for an Arrow aftermarket exhaust...even though I kept it stock,then later center drilling the mufflers 1/2" to be audible. It ran very well, under all conditions. The factory tune may have caused some hesitation.

The 2016 Moto Guzzi V7II has a new ECM program download at 600 miles, which only slightly helped cold and hot starts. The hot starts were the most irritating. It could be heat saturated, stop to go into a store for 15-30 minutes and it would bog if not allowed to idle for 1/2 a minute. I was suspecting the heated O2 sensors having to re-warm...just a guess. Might have been curable, but an altercation with the dealership owner ended that.

This 2014 CB1100 is flawless...cold or hot. Don't think I want the ECM touched!

Thanks to you all for the ongoing work on this issue that has flummoxed a number of members.

Has anyone yet tested for a vacuum leak? If so, what was the result?

Hopefully members are not shy about snugging 8 hose clamps!
Maybe just shy about reporting it?!

Just got back from a ride along Lake Mead up to Overton.
It was a relaxed day.
59.9 MPG going up North Shore at 55 MPH (elevation gain)
60.3 MPG returning via Interstate 15 at 65 MPH (75 MPH zone).
Can't believe I had the patience, but was determined to not give in to bursts of speed!

In the garage, bike went up on centerstand for chain lube (2358 miles)
Not finding any fasteners which needed torquing.
Got into the habit after riding Sportsters and started preaching post-ride inspection.

I find it interesting that some get that kind of mileage on their CB1100. Normal for me was 43mpg, some city, but mostly 45-60 country riding...maybe 49-50 if all hiway. And I don't ride crazy on the throttle.

I've wondered if there might be a correlation between bikes with high/low idle issue and overall lower mpg for those bikes affected.

That was an unusual run. Typical is 46 to 54. When calculating range between fuel stops, I use 48 MPG. 54 is fairly level at 70-75 MPH. 46 is 85 + and pulling some grades...with some speed bursts. Most city riding is on my way out of town.

[CBhooligan_imp]

Hey guys, I experienced the Idle speed instability problem for a while but it was luckily solved. I bought my bike with 5k miles and it was only after the 16k miles mark when I started experiencing very low idle to the point that it stalled a few times. I tried several things trying to fix the problem, I adjusted valves, cleaned injectors, changed spark plugs, air filter, (among other services and inspections like disconnecting the power commander and resetting procedures) and nothing helped. I was about to give up and just accept that my bike was just another CB that suffered from this common disease. Then, while I was cleaning electrical connections, I remember that I was using a cheap battery from Autozone and decided to replace it with a motobatt battery. The cheap battery from Autozone was only a few months old, but one day when I was riding far from home, the stock battery decided to give up. I was 2 miles from autozone and it saved my life. I never suspected the reason for this problem could be the battery because it would start right up every time. I had the battery tested and it was good, but maybe it was fact that it had lower specifications than those required by the cb1100 charging system and it was causing the low idle problem. I waited 3000 miles to report my problem/solution just to make sure the problem was solved. I know that my case can be an isolated case but hopefully it helps someone one day. cheers.

[pdedse]

Hey guys, I experienced the Idle speed instability problem for a while but it was luckily solved. I bought my bike with 5k miles and it was only after the 16k miles mark when I started experiencing very low idle to the point that it stalled a few times. I tried several things trying to fix the problem, I adjusted valves, cleaned injectors, changed spark plugs, air filter, (among other services and inspections like disconnecting the power commander and resetting procedures) and nothing helped. I was about to give up and just accept that my bike was just another CB that suffered from this common disease. Then, while I was cleaning electrical connections, I remember that I was using a cheap battery from Autozone and decided to replace it with a motobatt battery. The cheap battery from Autozone was only a few months old, but one day when I was riding far from home, the stock battery decided to give up. I was 2 miles from autozone and it saved my life. I never suspected the reason for this problem could be the battery because it would start right up every time. I had the battery tested and it was good, but maybe it was fact that it had lower specifications than those required by the cb1100 charging system and it was causing the low idle problem. I waited 3000 miles to report my problem/solution just to make sure the problem was solved. I know that my case can be an isolated case but hopefully it helps someone one day. cheers.

Dang it! I knew I shouldn't have traded-in my CB. : )

I have "moved on" with my Street Twin, but I haven't lost curiosity for what will become of this issue. I have the ST for less than two weeks and it's a nice bike, but I can't help but feel that it will be "bait" for a new CB somewhere down the line.

Glad to hear your problem has stayed away!

[SportsterDoc]

Hey guys, I experienced the Idle speed instability problem for a while but it was luckily solved. I bought my bike with 5k miles and it was only after the 16k miles mark when I started experiencing very low idle to the point that it stalled a few times. I tried several things trying to fix the problem, I adjusted valves, cleaned injectors, changed spark plugs, air filter, (among other services and inspections like disconnecting the power commander and resetting procedures) and nothing helped. I was about to give up and just accept that my bike was just another CB that suffered from this common disease. Then, while I was cleaning electrical connections, I remember that I was using a cheap battery from Autozone and decided to replace it with a motobatt battery. The cheap battery from Autozone was only a few months old, but one day when I was riding far from home, the stock battery decided to give up. I was 2 miles from autozone and it saved my life. I never suspected the reason for this problem could be the battery because it would start right up every time. I had the battery tested and it was good, but maybe it was fact that it had lower specifications than those required by the cb1100 charging system and it was causing the low idle problem. I waited 3000 miles to report my problem/solution just to make sure the problem was solved. I know that my case can be an isolated case but hopefully it helps someone one day. cheers.

I'd expect that cleaning electrical connections may have been the "cure".
To evaluate a battery, check voltage key off, key on and while cranking.

1. KEY OFF battery voltage, at the battery: Normal is 12.8, acceptable is 12.6 (standard lead acid battery, not AGM) to 12.8 for no load. If just taken off a charger, voltage may be 13 point something. The battery needs to sit for a while before a reading is useful. In the case of a bad cell, the other cells overcharge and give an almost normal reading, until load is applied.
• If lower, then battery is discharged and needs charging or
• Battery has a bad cell

2. KEY ON battery voltage (headlight on): Normal is not under about 12.5 initially, but will decline the longer that the headlight is on, without the motor running. Under no load, 12.5 volts indicates 50% discharge, but under load, it is just voltage drop.
• If lower, then battery is discharged and needs charging or
• Battery has a bad cell or
• Battery cable(s) have high resistance

3. KEY ON battery voltage while cranking: Normal is not under 10.5 volts
• If lower, then battery is discharged and needs charging or
• Battery has a bad cell or
• Battery cable(s) have high resistance or
• Starter is drawing too much current

4. If the bike is running, battery voltage at about 2,500 RPMs should be 13.8 to 14.8
• If not, then check stator resistance and regulator ground
• If the stator is not shorted to ground and resistance is within spec, the regulator or regulator ground is suspect

Nonetheless, glad that you solved it.

Hey guys, I experienced the Idle speed instability problem for a while but it was luckily solved. I bought my bike with 5k miles and it was only after the 16k miles mark when I started experiencing very low idle to the point that it stalled a few times. I tried several things trying to fix the problem, I adjusted valves, cleaned injectors, changed spark plugs, air filter, (among other services and inspections like disconnecting the power commander and resetting procedures) and nothing helped. I was about to give up and just accept that my bike was just another CB that suffered from this common disease. Then, while I was cleaning electrical connections, I remember that I was using a cheap battery from Autozone and decided to replace it with a motobatt battery. The cheap battery from Autozone was only a few months old, but one day when I was riding far from home, the stock battery decided to give up. I was 2 miles from autozone and it saved my life. I never suspected the reason for this problem could be the battery because it would start right up every time. I had the battery tested and it was good, but maybe it was fact that it had lower specifications than those required by the cb1100 charging system and it was causing the low idle problem. I waited 3000 miles to report my problem/solution just to make sure the problem was solved. I know that my case can be an isolated case but hopefully it helps someone one day. cheers.

Dang it! I knew I shouldn't have traded-in my CB. : )

I have "moved on" with my Street Twin, but I haven't lost curiosity for what will become of this issue. I have the ST for less than two weeks and it's a nice bike, but I can't help but feel that it will be "bait" for a new CB somewhere down the line.

Glad to hear your problem has stayed away!

Yep, and you may have solved it! But you did give several reasons for trading it. There, feel better?!

How are you liking the Street Twin?