CB1100 Idle speed instability problem

[SportsterDoc]

More emails between Max and popgun.
Max is favoring the TPS as being the cause of many of the issues.
We are continuing to research a replacement source.

In the meantime, how many CB1100 riders, who have experienced idle instability, have the following conditions:
1. Bike is parked outdoors, uncovered?
2. Bike is ridden in rain, especially heavy rain?
3. Bike is hosed off, occasionally/frequently?

If yes, to any of the above, has the TPS been unplugged (easy thumb release) and contacts checked for corrosion?

Note: Female/outer connector is facing up, which would likely funnel moisture, even though there may be an o-ring (oval) for the male/inner connector to press against.

For me:
1. Bike is parked outdoors, uncovered? Always garaged at night, on a two week trip, parked outside.
2. Bike is ridden in rain, especially heavy rain? Never heavy rain; light rain a few times
3. Bike is hosed off, occasionally/frequently? Have only washed the bike 2x; minimal water used.

In general, bike doesn't get washed much; I didn't see any sign of corrosion at the TPS connector.

Not likely a moisture/corrosion issue for you.
Because of the improvement after cleaning the TPS connector, it may simply be that the contacts were not mating well until disconnected and reconnected, whether cleaned or not.

Had you previously unplugged the TPS?

Do you recall ever bumping the TPS / TPS connector / TPS wirinig?

I had not previously unplugged the TPS connector--I didn't even know what it was.
I may have lightly sprayed the area with water after cleaning 2x, but no blasting spray.

jdvalero confirmed for me yesterday that the idle issue has not returned for him since he unplugged his TPS connector and "realigned"? one of the receiving holes of the connector. That was nearly a month ago.

He also mentions that his issue first started after a hard hiway run and wonders if vibration was what brought about a bad contact at the TPS connector.

I hold my breath each ride wondering if the problem will return, but I can tell you that since unplugging and cleaning the TPS connector that I've had the longest run of nearly no issue (slight dip to 900rpm 2x) since the problem started in July.

However, this stretch coincides with much cooler temps. We'll see in time. With Oregon rains and cold days, it's hard to get any rides in, but some dry weather is supposed to come middle of the week.

Loosening the TPS fasteners, motor off, ignition on, voltmeter connected (similar to Max's photo) is the proper way to set the base throttle closed voltage. Arbitrarily moving it is not wise, although I would expect that the throttle calibration procedure may compensate for a minor error in not having 0.5 vdc at throttle closed.

A Honda software update solved my idle problem til now since a few months. The reason for an update were faults in the programming of the fuel injection. So the explanation of the mechatronic. I will see for how long it will last with my 2013 CB.

I recommend everyone with this problem to achieve the same, which will take some effort before trying out other 'solvations' in the meaning of trial and errors attempts in a more or less 'dark room'.

Wisedrum

What was the upgrade date of the software?
What is the software number?
Does 2014 model already have that update?

A Honda software update solved my idle problem til now since a few months. The reason for an update were faults in the programming of the fuel injection. So the explanation of the mechatronic. I will see for how long it will last with my 2013 CB.

I recommend everyone with this problem to achieve the same, which will take some effort before trying out other 'solvations' in the meaning of trial and errors attempts in a more or less 'dark room'.

Wisedrum

So, are you recommending that no one follow the diagnostic instructions per the Honda Factory Service Manual?

The last few pages of this very long thread have been a quest for empirical data to perhaps allow remote diagnosis...not trial and error.

A. Snugging clamps on the intake hoses, to minimize the chance of a vacuum leak, is a standard motorcycle maintenance procedure. A follow-up check is to apply an unlit propane torch (or WD-40, if you don't mind the mess) while the engine is running, to check, for a change in idle speed.

B. Measuring resistances and voltages, per the FSM is standard diagnostic procedure.

C. Checking for active or stored codes is standard diagnostic procedure.

What suggestions are you labeling as trial and error?

What would you suggest if a software upgrade does not solve the issue?

At this point, it is likely that there are three possible (or combined) issues for high/low idle issues:

1. TPS sensor / TPS connector / TPS wiring / voltage to TPS from ECM.

2. IACV motor / IACV plunger operation / IACV wiring

3. Vacuum leak associated with intake manifold tubing / intake hose clamps loose.

Many, many times carb removal and reinsertion without lubrication (water, diluted liquid soap or spit) has resulted in a vacuum leak on Sporsters (Keihin CV40 into single hose to manifold to both cylinders). Many, many times the vacuum line on pre 2006 models to the vacuum operated petcock and the Y to the VOES (Vacuum Operated Electrical Switch which signals advance/retard to ignition module) on pre 2004 models has been an issue.

Although I have been wrenching for over half a century, I certainly do not know everything...I am still learning...but what has been posted is directly from or based upon the FSM.

I absolutely despise throwing parts at an issue and a very expensive throttle body assembly does that for 2 1/2 of the 3 issue categories.

Although Harley, Triumph and Moto Guzzi have two year warranties, Honda USA is only one year. We don't want idle issues to push a CB1100 rider into an unnecessary throttle body replacement, simply because full diagnostics have not been done.