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tps evaluating for ii issues
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SportsterDoc Offline
1st Service Completed

southern Nevada
Posts: 221
Joined: Nov 2017
Post: #41
RE: tps evaluating for ii issues
Dave-Have you checked that the TPS connector contacts are fully seated in the connector insulator?

Automotive and motorcycle connectors typically have connectors crimped (or soldered) to wires, which are pushed into the connector insulator from the rear. The contact has one or two clips/prongs/barbs which snap into a retention feature of each cavity.

During the assembly process, if each wire/contact is not fully pushed into each cavity, the contact "floats", removing pressure on the mating surfaces.

This can be discovered by (a) pulling on a wire and finding the contact is pulled out or (b) pushing on a wire and hearing a snap/pop as the clip seats.

An unseated contact can cause repeat intermittent issues.

Recent bikes:
2014 Honda CB110 standard (new 7 Nov 2017)
2018 Yamaha XT250
2016 Moto Guzzi V7II
2017 Yamaha TW200
2012 Triumph Bonneville
2002 Harley-Davidson Sportster 1200 Sport
2003 Harley-Davidson Sportster XLH883
(This post was last modified: 01-19-2018 09:03 AM by SportsterDoc.)
01-19-2018 08:15 AM
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max Online
1st Service Completed

Posts: 55
Joined: Sep 2017
Post: #42
RE: tps evaluating for ii issues
Thanks Cormanus et all, that is encouraging to hear, i try to post as little and minimalistic as i think is required to assist Dave in this case, rather than blabbering on about technology endlessly in order to not pollute the forum.

From a very early age i have been interested in what makes things tick and faultfinding is one of my hobbies, this one interests me because i find it simply unfair to the affected customers who are unable to gather support for their case.

What i try to achieve is to separate the two parts that are responsible for this issue and isolate the one which is the cause of the discomfort on an otherwise immaculate machine.

there have been good efforts made in the past and it is very helpful to read through all the posts several times to sift out the relevant info, that takes more time than your average member is prepared to do, but i copied and pasted most of the info and condense it even more so the essential info is all in a small place.
some of the offered solutions have been varied and many, so that is why i focus on one suspect part so heavily.

lucky for us this part can be eliminated completely by unplugging it, and IF the erratic behaviour of the bike disappears we have found the source of the problem, quite simply.

The trick in proving that is to run the bike for a long enough period WITHOUT the tps to ensure that it HAS lost it's fluctuating behaviour, and the ultimate test is to replace the tps with a new one, and if that fixes the problem for a long time swap it out for the suspect tps and see if the fault returns.

If the issue disappears with the tps unplugged there can be two possibilities;
1 the tps itself or
2 the connection between the tps and the ecm.

if the tps is replaced we will never know which one was the actual problem and it may well return at some stage, remember all of the affected bikes have been running fine and passed inspection in the factory, so something has changed and it is not the software.

Dave, my bike is a 2010 model, the first one to be assembled in japan, i would expect the software to be a different version number from yours, i am assuming that the" limp mode" in your bike ( to allow riding it home with a faulty part ) is of a later date and has more limitations programmed into it to protect the engine , this may be significant in trouble shooting, suppose all the affected bikes have a version of software that is limited to 3000 rpm, that would make identification very easy, but that is only speculation on my part.

Hope this helps; max

2010 cb1100 candy red
2006 cb919 hornet black
1977 cb550 k3 1st owner
01-19-2018 12:29 PM
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Dave Offline
Running Like a Top

San Diego, ca
Posts: 356
Joined: Jan 2014
Post: #43
RE: tps evaluating for ii issues
Hi all, here's my latest update. I really wanted to perform all of the TPS voltage and resistance tests today, and inspect for loose connections, but my 2 hr planned car repair ending up being a 5 hr job:

• Temperature in the low 60’s.
• All sensors connected.
• Initial start – normal approx. 1,400 RPM high/cold idle.
• Idle settles into approx. 1,050 RPM after approximately 4 miles and 5 stop lights –approx. 3 miles of freeway.
• Turn bike off with key, allow to sit approximately 20 minutes. Restart and idle speed = 1,050 RPM.
• Ride approximately 3 miles, 5 stop lights, idle speed remains at 1,050 RPM.
• Turn bike off with key, bike sits approx. 15 minutes.
• Restart bike, 1,050 RPM idle.
• 2 stop lights, approx. ½ mile of freeway, stop at freeway exit and idle = 700 RPM, but will slowly work its way back to 1,050 RPM. 3 more stop lights and exact same 700 to 1,050 RPM idle each time.
• Turn bike off with key. Bike off approx. 15 minutes.
• Disconnect EOT sensor. Note: Disconnecting the EOT sensor when this bike was exhibiting the high (1,500 RPM) idle always cured the high idle problem immediately. Bike has not experienced a high RPM idle condition for over a year.
• Restart bike, idle = 1,050 RPM.
• Ride approx. 5 miles, 8 stop lights. Idle speed = 800 RPM after approx. 1 mile, at each stop light, but steady. Idle will not slowly work its way up to 1,050 RPM like it does with all sensors connected.
• Turn bike off with key. Plug EOT sensor back in. Restart bike. Idle = 1,050 RPM.
• Ride bike approx. 3 miles. After approx. .5 mile, at second stop light 700 RPM idle returns. At fourth, fifth, and sixth stop light the bike stalls, but will restart. Head to local college where I can ride in the parking lot.
• Turn bike off with key. Unplug TPS. Restart, idle = 1,050 RPM. Ride approximately 3 miles around parking lot, stop and go. Idle speed = approx. 800 RPM after first mile, but steady – does not creep back up to 1,050 RPM like it does with all sensors connected. Does not stall.
• Turn bike off with key, plug TPS back in. Restart – idle = 1,050 RPM. Idle speed remained at 1,050 RPM for approx. 3 miles, and 4 stops lights. After 3 miles the 700 RPM and creeping up to 1,050 RPM idle returned.
• Returned home with 700 RPM idle condition. Blipped throttle a few times, and each time it would drop to 700 RPM, and creep back up to 1,050 RPM.
• Put bike away for the day.

In summary: Disconnecting either the EOT sensor or the TPS sensor does not eliminate the low idle problem (disconnecting the EOT sensor did cure the high idle condition this bike had a year ago). Disconnecting either of these sensors does cause a difference in the low idle condition, and that being once the low idle condition is reached, it will not slowly creep back up to a normal, 1,050 RPM idle. Also, with either sensor disconnected the engine seemed more stable, and less reluctant to want to stall, than it does with the sensors connected normally.

Hope this gives some insight to the guys working so diligently to try to solve this. I apologize for lack of video, but (go ahead and laugh) I do not own a smart phone (but my wife does).
(This post was last modified: 01-20-2018 06:58 PM by Dave.)
01-20-2018 06:55 PM
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Houtman Offline
High Mileage

Posts: 888
Joined: May 2013
Post: #44
RE: tps evaluating for ii issues
I do not own a smart phone either.
If Warren Buffett can get by with a flip phone than I should be able to do the same .
01-20-2018 07:19 PM
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max Online
1st Service Completed

Posts: 55
Joined: Sep 2017
Post: #45
RE: tps evaluating for ii issues
Geez Dave, i was waiting for your update but by the time i came home it had already fallen off the list of new messages, so i just found it just now.

Right, very detailed resume indeed, as usual i read it 4 times just to get it in my head, just a quick remark; if the tps is unplugged the ecm " invents" a new idle setpoint which is higher than 0.5 volts, i have seen this happen on a video and was surprised, ( this is speculation from me but it seems to fit what happens every time the tps is plugged back in ).
When the tps is re- connected it re-learns the faulty voltage and plays up again ( my assumption ).

During all this explaining i must have given you the wrong idea, to be clear;
-------- just do a complete run with the tps unplugged for the length of the entire trip.--------

sofar there are no fluctuations with it unplugged, let's see if that keeps happening, don't worry about where the idle point is as long as it stays in the same place and doesn't change.

Oh just one last thing ; does your bike exceed 3000 rpm with the eot sensor unplugged?


2010 cb1100 candy red
2006 cb919 hornet black
1977 cb550 k3 1st owner
Yesterday 01:33 AM
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