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tps evaluating for ii issues
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max Offline
1st Service Completed

auckland
Posts: 138
Joined: Sep 2017
Post: #1
tps evaluating for ii issues
UPDATE; new procedure for tps testing.

this is another approach in diagnosing the Idle Instability Issue.

In order to isolate which of the two parts is the source of trouble on the throttle body i discovered an interesting way to isolate the tps, you unplug it!

the following video shows how to do this and what tools are required, most of us can follow this procedure.

1 if your bike runs better after the tps is disconnected that would be an indication the tps is bad.
2 if it still has the same problem after disconnection it MAY be the iacv.

During the test drive i noticed three things;
1 cold idle is at 1250 rpm.
2 throttle response is " softer " and smooth handling may be required to keep it running on startup.
3 my exhaust vacuum valve did not operate ( think the bike is in a different mode )

It appears ok to drive this way but just to be on the safe side i would not recommend long periods unplugged riding.
What may work for you is giving you the length of cable as shown in the video but leaving it connected, go for a drive and when the idle is acting up stop, disconnect the connector and see what difference it makes, even several times to make sure the method is repeatable.

If success is achieved i suggest making a video showing; difference in rpm, connector disconnected and connected possibly several times.
this can easily be done with the bike running on the side stand.
if this is done correctly it may well lead to a refund or recognition of sorts by the dealer and dispel uncertainty.

This method has been done by several service personnel and documented as such.

Let's hear your experience with this method, it has to be the simplest to date because we really need some feedback from you affected owners.

https://youtu.be/gCALpJRQA8s

cheers max
12-29-2017 02:45 PM
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SportsterDoc Offline
Running Like a Top

southern Nevada
Posts: 418
Joined: Nov 2017
Post: #2
RE: tps evaluating for ii issues
Max
Thank you for the effort that you are putting into this.
I emailed you regarding details of first conclusion.

For now, just a couple comments:
1. My TPS wires have enough slack to just unplug, which I have done a couple times...but good to show how the air box side covers are removed.

2. Above the TPS, at 10 & 11 o'clock, the intake clamp screws (8mm/Phillips) for the left cylinder can been seen at video 1:32 to 1:44 minutes. This is what I have been suggesting be "snugged".

14 Honda CB1100 std
18 Yamaha XT250
16 Moto Guzzi V7II
17 Yamaha TW200
12 Triumph Bonneville
02 H-D Sportster 1200S
03 H-D Sportster XLH883
76 Honda CB750F
75 Honda CB360
70 Yamaha CT1
72 Yamaha CT2
72 Yamaha AT2
70 Honda SL350
70 Honda CL350
67 Honda CL160
67 Honda CB160
62 Honda CA110
12-29-2017 06:34 PM
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SportsterDoc Offline
Running Like a Top

southern Nevada
Posts: 418
Joined: Nov 2017
Post: #3
RE: tps evaluating for ii issues
Max, I received and responded to your emails.

At this point, if unplugging the TPS results in better operation, I'd suggest checking the TPS voltages per this post:

http://cb1100forum.com/forum/showthread....20&page=66

and per you post 632 of that thread. Your video shows how easy it is to check output voltage.

Also, if it is a TPS issue, it may only be a bad connection...a common issue on many/most motorcycles.

I understand that you are working at making diagnosis easier, but would not recommend less than the full diagnosis.

There are times on the Sportster forum when the correct diagnosis came early in a thread, but I did want the original poster to buy a component until all the checks were done...did not want to be blamed for any waste of $ spent.

14 Honda CB1100 std
18 Yamaha XT250
16 Moto Guzzi V7II
17 Yamaha TW200
12 Triumph Bonneville
02 H-D Sportster 1200S
03 H-D Sportster XLH883
76 Honda CB750F
75 Honda CB360
70 Yamaha CT1
72 Yamaha CT2
72 Yamaha AT2
70 Honda SL350
70 Honda CL350
67 Honda CL160
67 Honda CB160
62 Honda CA110
(This post was last modified: 12-29-2017 10:09 PM by SportsterDoc.)
12-29-2017 10:04 PM
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SportsterDoc Offline
Running Like a Top

southern Nevada
Posts: 418
Joined: Nov 2017
Post: #4
RE: tps evaluating for ii issues
In Max's video, note the number of times the CEL blinks: 8, which is the DTC for TPS voltage. It does not specify -1 or -2 for whether voltage is low or high, but it does specify a TPS issue.

14 Honda CB1100 std
18 Yamaha XT250
16 Moto Guzzi V7II
17 Yamaha TW200
12 Triumph Bonneville
02 H-D Sportster 1200S
03 H-D Sportster XLH883
76 Honda CB750F
75 Honda CB360
70 Yamaha CT1
72 Yamaha CT2
72 Yamaha AT2
70 Honda SL350
70 Honda CL350
67 Honda CL160
67 Honda CB160
62 Honda CA110
12-30-2017 10:37 AM
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Dave Offline
Running Like a Top

San Diego, ca
Posts: 411
Joined: Jan 2014
Post: #5
RE: tps evaluating for ii issues
Hi Max. Great video, thank you. For clarification: Are you suggesting to disconnect the TPS when the high / low idle condition occurs and then seeing if this cures the problem? I will try this the next time the idle condition rears its ugly head and report back. 3 days ago my bike exhibited the worst case of low idle and stalling ever. After 20 minutes of perfect running (around town, slow speeds, stop & go), the low idle suddenly returned. The bike stalled three times, and once it even stalled when shifting from first to second gear (I can force it to keep running by increasing the RPM when stopped at a light, but to me, it sounds like an extremely lean fuel mixture). I turned the bike off with the key, and took out my wife's smart phone to video the condition but when I restarted the bike it returned to running perfectly ( and remained running perfect for the rest of the ride - about 10 more miles, a mixture of stop and go and freeway). Just to let you know, I have discovered that unplugging the EOT sensor when the low idle condition occurs will immediately cure the problem (but I always turn the bike off with the key before unplugging the EOT sensor). I have ridden my bike on multiple occasions with the EOT sensor disconnected and never experiences the low idle / stalling condition.
01-03-2018 11:09 PM
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max Offline
1st Service Completed

auckland
Posts: 138
Joined: Sep 2017
Post: #6
RE: tps evaluating for ii issues
(01-03-2018 11:09 PM)Dave Wrote:  Hi Max. Great video, thank you. For clarification: Are you suggesting to disconnect the TPS when the high / low idle condition occurs and then seeing if this cures the problem? I will try this the next time the idle condition rears its ugly head and report back. 3 days ago my bike exhibited the worst case of low idle and stalling ever. After 20 minutes of perfect running (around town, slow speeds, stop & go), the low idle suddenly returned. The bike stalled three times, and once it even stalled when shifting from first to second gear (I can force it to keep running by increasing the RPM when stopped at a light, but to me, it sounds like an extremely lean fuel mixture). I turned the bike off with the key, and took out my wife's smart phone to video the condition but when I restarted the bike it returned to running perfectly ( and remained running perfect for the rest of the ride - about 10 more miles, a mixture of stop and go and freeway). Just to let you know, I have discovered that unplugging the EOT sensor when the low idle condition occurs will immediately cure the problem (but I always turn the bike off with the key before unplugging the EOT sensor). I have ridden my bike on multiple occasions with the EOT sensor disconnected and never experiences the low idle / stalling condition.

Thank you, Dave.
You have been very helpful and precise, i have read your comment very carefully several times.

In the past there have been at least two cases where the complete throttle body has been replaced and with 100% sucess.

There have also been other repairs performed with sucess.
as you know i have been working on the eot sensor as well but have not yet found any fault with it, but i know first hand that it is part of the process for the iacv.

My first mission is to prove or disprove the tps, because it is by far the most simplest part to work with, if we can find that unplugging it makes a decisive difference on several bikes we are a step closer, if we find that it makes no difference at all we can concentrate on the next item, but that will probably be beyond some owners to accomplish by themselves.

Think the best way to do in your case is to first make sure the tps can be unplugged by making sure the wiring is long enough to allow this by following the tips in the video so the connector is not damaged by forcing it and stretching the wires.

Then go and ride the bike ( with the camera, great idea ) and wait until the issue happens frequently ( reliably enough ) whilst filming unplug the tps when the engine is running, blip the throttle and see if it has any effect, plug it back in and so on several times.
the reason is that it needs to be repeatable to be proof enough, if it has the desired effect you can go for a short ride and repeat the process, what we want is conclusive evidence.
what you are doing is an a-b test back to back, several times, i'm sure you know what i mean

It may not help at all, but you are the closest to an answer we have so far and i really appreciate your help.
Happy new year;max
01-04-2018 12:04 AM
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Dave Offline
Running Like a Top

San Diego, ca
Posts: 411
Joined: Jan 2014
Post: #7
RE: tps evaluating for ii issues
Hi Max, thank you, and happy new year to you too! I haven't had time to ride nearly as much as I would like because other priorities keep getting in the way (like a leaking crankshaft seal on my truck, a leaking head gasket on my car, and clogged plumbing in my house), but I will definitely check the wire on my CB this weekend and have it ready to unplug the next time I ride. My idle problem comes and goes at random, so please understand I may not have a answer for you quickly. Thanks again for all the work you're doing!
01-04-2018 06:20 AM
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SportsterDoc Offline
Running Like a Top

southern Nevada
Posts: 418
Joined: Nov 2017
Post: #8
RE: tps evaluating for ii issues
Likely possibilities for an intermittent issue:
1. Failing component
2. Poor connection

This is supported by the FSM, page 5-15:

DTC 8-1 (<0.3 vdc) "Loose or poor contact of TP sensor connector. TP sensor or its circuit malfunction"

DTC 8-2 (>4.93 vdc) "TP sensor or its circuit malfunction"

At the beginning of each sensor checking procedure, the FSM admonishes "before starting, check for loose or poor contact..."

I do not want to interfere with your teamwork with Max, Dave, but if the issue is related to the sensor, unplugging it and insuring a good connection, may end the issue.

One more thought: If a poor connection, either incoming 5 vdc power and/or 0.5 to 4.5 vdc output will be lessened. If not out of range, no DTC, but the ECM will think that the throttle is not as far open as it actually is, which would be expected to cause shorter injector pulses, making it lean, which might cause low idle and/or stalling. This should be checked before replacing the TPS.

14 Honda CB1100 std
18 Yamaha XT250
16 Moto Guzzi V7II
17 Yamaha TW200
12 Triumph Bonneville
02 H-D Sportster 1200S
03 H-D Sportster XLH883
76 Honda CB750F
75 Honda CB360
70 Yamaha CT1
72 Yamaha CT2
72 Yamaha AT2
70 Honda SL350
70 Honda CL350
67 Honda CL160
67 Honda CB160
62 Honda CA110
01-04-2018 09:45 PM
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Dave Offline
Running Like a Top

San Diego, ca
Posts: 411
Joined: Jan 2014
Post: #9
RE: tps evaluating for ii issues
Thank you Max and Sportsterdoc. My bike has never exhibited an error code, except when I unplug the EOT sensor. I checked yesterday, and I am able to unplug the connection to the TPS. I think I'll buy some contact cleaner and spray it on the connection and see if that does anything. Some members have had their idle problem corrected under warranty when the entire fuel injection was replaced; I wonder if Honda chose this repair because the TPS was faulty, and on the CB1100 the TPS is not available separately? Thank both you guys so much for all the effort you're putting into this!
01-05-2018 06:28 AM
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Houtman Offline
High Mileage

NC USA
Posts: 1,059
Joined: May 2013
Post: #10
RE: tps evaluating for ii issues
I think that Sportersdoc and Max put more effort in solving this problem than Honda USA does !
01-05-2018 07:19 AM
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