Throttle Position Sensor TPS Part Number

Our bikes (both 2010s) have NOT thrown a code.( ??) They both run fine until normal operating temp. They miss, pop, and will not idle after that. If you keep it above 3k rpm it will run fine. So I am guessing TPS. I did install new crank sensor, didn't help...wishful thinking. I have checked the obvious items, plugs, cap etc. Guess I will try the Yamaha TPS.

Seems odd that two different NT's in the same family had TPS failures at the same time. Any other variables possible?

The issues were a few months a part. We have checked every obvious solution, gas, plug, etc. Have no idea. They have the EXACT same symptoms. Both bikes are well taken care of, no abuse and well maintained. The only common factor was a trip to Colorado. My dad's started acting up shortly after the trip, mine was a few months later. They both have around 10,000 miles on them. I just wish they would activate a code. One would think it would while it is going through its "missing popping" spell. Thankfully we have other bikes,so the Nt's are just furniture until we can find a solution. Honda dealers have no idea and claim to know nothing of these type of problems.

hk9151 said:

The issues were a few months a part. We have checked every obvious solution, gas, plug, etc. Have no idea. They have the EXACT same symptoms. Both bikes are well taken care of, no abuse and well maintained. The only common factor was a trip to Colorado. My dad's started acting up shortly after the trip, mine was a few months later. They both have around 10,000 miles on them. I just wish they would activate a code. One would think it would while it is going through its "missing popping" spell. Thankfully we have other bikes,so the Nt's are just furniture until we can find a solution. Honda dealers have no idea and claim to know nothing of these type of problems.

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Have you replaced the spark plug caps?

dnktng said:

The 3 page Service Bulletin in it's entirety.

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I have not. We looked them over but since it does not fail under hard acceleration we ruled that out. I will probably order a pair and try it. They are cheap enough. I have it all apart so they are easy to access right now.

I was also going to suggest plug caps as you have classic symptoms for this problem and there is a Honda service bulletin for your year model.

Please let us know if the plug cap change works or not.

Seagrass

hk9151 said:

The issues were a few months a part. We have checked every obvious solution, gas, plug, etc. Have no idea. They have the EXACT same symptoms. Both bikes are well taken care of, no abuse and well maintained. The only common factor was a trip to Colorado. My dad's started acting up shortly after the trip, mine was a few months later. They both have around 10,000 miles on them. I just wish they would activate a code. One would think it would while it is going through its "missing popping" spell. Thankfully we have other bikes,so the Nt's are just furniture until we can find a solution. Honda dealers have no idea and claim to know nothing of these type of problems.

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You say that if you keep the revs above 3000 it runs OK.
When you close the throttle does the engine stall/stop?
If so, when you try to restart it without touching the throttle does it crank over but not start?
If you open the throttle whilst trying to restart it does it then start and keep running if you hold the throttle open?
If yes to the above have a look at the tailpipe whilst cranking and immediately after restart.
Is there a wisp of black smoke?
If yes the engine is flooding.
Take the plugs out and have a look at them. If they are black that will comfirm flooding.
If it is not logging a fault code it means that all sensors are operating within specs but it does not mean that a sensor is not faulty.
A faulty sensor can produce the right signal but at the wrong time and the ECU will not see that as a fault as long as it is within the normal range of output.

Macka

hk9151 said:

I have not. We looked them over but since it does not fail under hard acceleration we ruled that out. I will probably order a pair and try it. They are cheap enough. I have it all apart so they are easy to access right now.

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Generic long angled NGK plug caps also work well. I think the number is VDO5F. You don't have to use Honda NT specific caps.

Macka said:

You say that if you keep the revs above 3000 it runs OK.
When you close the throttle does the engine stall/stop? Yes
If so, when you try to restart it without touching the throttle does it crank over but not start? Yes
If you open the throttle whilst trying to restart it does it then start and keep running if you hold the throttle open? Yes
If yes to the above have a look at the tailpipe whilst cranking and immediately after restart. Yes
Is there a wisp of black smoke? Yes
If yes the engine is flooding. My guess as well
Take the plugs out and have a look at them. If they are black that will comfirm flooding. Have, they looked ok..brown
If it is not logging a fault code it means that all sensors are operating within specs but it does not mean that a sensor is not faulty.
A faulty sensor can produce the right signal but at the wrong time and the ECU will not see that as a fault as long as it is within the normal range of output.

.

Macka

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* See answers above*
It only fails at full operating temp. When it does start back it sometimes sounds like its hitting one 1 cylinder until revs are up above 3k.

Short answer: MAP Sensor.

I forgot to mention the "1 cylinder symptom". I am glad that you picked-up on that.

Longer answer: I was sitting here this morning typing out a long and very technical answer for you but I was called out to the workshop to talk to a customer.
By the time I got back to my desk the forum had timed-out and I lost 30+ minutes of research/typing.
If you want to know what exactly is going on and why, I can try to type it all out again when I will not be dragged away from my desk.
If you replace the MAP sensor I am confident that it will be fixed.

If you want I can give you a few clues on how to save a lot of money on this.

Macka

Saving money is always good. I just want them fixed. Sorry you lost your writings. I do not want to be a burden. I ordered the caps. So map sensor could be the culprit? Can it be cleaned?(some auto map sensors can be) .This sensor would not throw code?

Ok...I have been playing with the tps. I adjusted it and it did improve the problem. The first adjustment had it idling at about 850 but it did not stall,, buck or pop in second gear pull from 1500 rpm up to 3k. Before it would pop and die. It would still sometimes die if I grabbed a handful from idle. The second adjustment had it idling at 1100. This was a HUGE improvement. It will pull from idle without any issues but stil has an off idle stumble. So I am pretty sure the tps is bad.

Macka said:

Short answer: MAP Sensor.

I forgot to mention the "1 cylinder symptom". I am glad that you picked-up on that.

Longer answer: I was sitting here this morning typing out a long and very technical answer for you but I was called out to the workshop to talk to a customer.
By the time I got back to my desk the forum had timed-out and I lost 30+ minutes of research/typing.
If you want to know what exactly is going on and why, I can try to type it all out again when I will not be dragged away from my desk.
If you replace the MAP sensor I am confident that it will be fixed.

If you want I can give you a few clues on how to save a lot of money on this.

Macka

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Could the TPS adjustments fool the MAP or is my previous post a solid indicator?

hk9151 said:

Could the TPS adjustments fool the MAP or is my previous post a solid indicator?

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I believe that the TPS adjustment is hiding the problem rather than solving it.
The symptoms you describe EXACTLY fit a faulty MAP Sensor.
I know this because I HAVE BEEN THERE.
I have been down the same road as you adjusting the TPS with pretty much the same results and then replaced the MAP to solve the problem.
Remember that the TPS is a mechanical sweeper and usually will not show any symptoms at a fixed throttle position unless you stop the sweep at EXACTLY the right spot.
It almost always shows as a hesitation or flat spot as you wind on the throttle.
The MAP is a piezo crystal under vacuum (variable pressure) to produce a voltage.
In my first attempt to explain this, which got lost in the time-out, it may have been easier for you to understand.
Another consideration is that if the TPS WAS faulty, even with a "dead" spot, it would log a fault code because the voltage would drop to zero momentarily and the ECU will never accept zero volts as a signal from a TPS. It must always be between 0.3 and 5 volts.
I am 99.999% sure that the MAP Sensor is your problem BUT you MUST ensure that you set the TPS back to no more than 0.6 volts with a closed throttle (preferably 0.45-0.5 volts) or you may still have strange symptoms without a fault code.
If you look at the wiring diagram you should be able to work out how to set the voltage correctly.
If not, let me know and I will describe it to you.
The MAP Sensor is common to many Honda motorcycles but not all.
You should be able to pick up a second-hand unit for $20 or so.

Macka

PS: I am off for a ride in the country to have lunch with friends at a country pub. 300+ km in great weather with great company is too good to pass up!

I put everything back together. TPS is 0.527 and 4.52 @ WOT. Ordered the MAP sensor....hurry up and wait now.

hk9151 said:

I put everything back together. TPS is 0.527 and 4.52 @ WOT. Ordered the MAP sensor....hurry up and wait now.

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Those are good figures.
Good Luck but I don't think that you will need it.
The MAP Sensor should fix it.
Mine had exactly the same symptoms as yours and a secondhand MAP off a CB600R fixed it.
It took me three months to figure out what was wrong because it only played-up three times.
It has now been almost a year and the symptoms have not returned.

Macka

I got the map sensor and put the spark plug caps on. I have ridden 250 miles so far without a problem. I will install the spark plug caps on my Dads NT this week before I buy a map sensor.

hk9151 said:

I got the map sensor and put the spark plug caps on. I have ridden 250 miles so far without a problem. I will install the spark plug caps on my Dads NT this week before I buy a map sensor.

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I am glad that it is now running well but as an experienced mechanic I can say with authority that you should not have replaced both parts together.
As both jobs are relatively easy you should have done one or the other as that would tell you whether you had isolated the problem or not.
As your bike now seems to be running well you have no idea which of the two was the cause of the trouble.
I had been down the same path replacing the plug caps first, it made no difference.
Sincerely though, Good Luck.
The important thing is that it now runs well.

Macka

its looks like he is going to take that path with the second bike by replacing the plug caps first. I find it unlikely that two motorcycles in the same family would have MAP sensors fail at almost the same time in particular when it does not seem to be a common problem with the NT. What is a common problem was the plug caps which seems to me to be the more likely culprit. I guess we will know soon enough how the plug cap change works on bike number two.

Macka said:

I am glad that it is now running well but as an experienced mechanic I can say with authority that you should not have replaced both parts together.
As both jobs are relatively easy you should have done one or the other as that would tell you whether you had isolated the problem or not.
As your bike now seems to be running well you have no idea which of the two was the cause of the trouble.
I had been down the same path replacing the plug caps first, it made no difference.
Sincerely though, Good Luck.
The important thing is that it now runs well.

Macka

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I should have written that more clearly. I got the map sensor a day after I received the spark plug caps. It was the caps that fixed it. Sent the sensor back yesterday. I'm sure the caps will fix his as well, but if not I will try the map sensor next. Thanks for all the help and advice. It still blows my mind that caps would fail at such low rpm but work under a load up to redline.