FJRiders.com

Spent the last 3 days riding with Viper Dad, ride report to follow one day soon.

He started complaining about the bike surging quite badly if he was holding the throttle still. For example, in most gears (not positive about 1st or 5th), if he's holding 4,000 rpm (or any steady rpm), the bike starts surging pretty badly, causing a buck jumping like situation. It doesn't do it all the time, but it does it a lot.

He's got a new air cleaner, new plugs, throttle bodies synched, tier 1 gas, always.

At this point, I'm thinking throttle position sensor?

Any thoughts, things to check, or ways to diagnose to isolate for certain? Or just buy another one, swap it out, and see if it fixes it?

One could try to guess if that surging occurs at a certain throttle opening (aka, position)... and if so, one could suspect TPS. There is a second one called Accelerator Position sensor (under the throttle bodies, right side), but I haven't heard of anybody replacing one.
First check MAP sensors that the vacuum lines aren't gummed up with waxy residue, and on the MAP sensor vacuum nipples as well.... two of them (official name Intake Air Pressure Sensor). If those are clean and problem persists, go for the TPS replace.
Ionbeam may chime in with how to detail check a TPS by backprobing the connector........

I’ve never had surging, though sport mode can feel like it sometimes.

I had symptoms similar to what you described on my 2014. It was a failed throttle position sensor.

Forgot to mention, same results in Touring and Sport mode. We tried to isolate it best we could while riding. Under any acceleration, it went away, it only appeared while a constant position was held, like going through a long, sweeping turn.

TPS will most likely act up in lower throttle openings, say 10-15% where the contact wipers reside the most... wearing into the ceramic resistance board. Acceleration means you twisted the throttle into a much lesser used area.

I am also betting on the TPS. Some people have claimed that a shot of a suitable contact cleaner will help. Might be enough to diagnose the problem but I would NOT expect any benefit to last very long. I think I would try that before replacing.

Have a look at this thread from the other sandbox. Doesn't cost anything to give it a try.
https://www.fjrforum.com/topic/171796-t ... nt-1364032

The TPS contact area is completely sealed, I don't see how anyone could shoot contact cleaner in there. You have to destroy the TPS to take it apart. Maybe they are lubing the drive area that might have a bit of dirt causing jerky movement??

What Ray says -- it's sealed. The problem isn't dirt, the resistive material wears out. There is some additional TPS information here.

raYzerman wrote: ↑Mon Oct 05, 2020 9:41 am The TPS contact area is completely sealed, I don't see how anyone could shoot contact cleaner in there. You have to destroy the TPS to take it apart. Maybe they are lubing the drive area that might have a bit of dirt causing jerky movement??

Possibly - I just remembered the post and linked it. I was under the assumption that it could be dismantled non-destructively. Obviously not the case - not sure what he was doing...

My experience is when the material gets worn, might as well replace.

Going into mine now I can feel my arm. What are normal MAP levels at idle?

You might find this helpful.

https://www.fjriders.com/forums/viewt ... 8#p104098

Road Runner wrote: ↑Mon Oct 05, 2020 8:29 pm You might find this helpful.

https://www.fjriders.com/forums/viewt ... 8#p104098

That’s funny, it’s the same problem on the same bike. I had forgotten about that post. I’ll have to try that.

Festus wrote: ↑Mon Oct 05, 2020 9:08 pm

Road Runner wrote: ↑Mon Oct 05, 2020 8:29 pm You might find this helpful.

https://www.fjriders.com/forums/viewt ... 8#p104098

That’s funny, it’s the same problem on the same bike. I had forgotten about that post. I’ll have to try that.

The root cause wasn't found IIRC. Bet the TPS will fix it.

Festus wrote: ↑Mon Oct 05, 2020 9:08 pm

Road Runner wrote: ↑Mon Oct 05, 2020 8:29 pm You might find this helpful.

https://www.fjriders.com/forums/viewt ... 8#p104098

That’s funny, it’s the same problem on the same bike. I had forgotten about that post. I’ll have to try that.

Well, it's not like it's MY bike or anything I have my own issues, on this past ride, I got a diagnostic code of 12, which won't let the bike start. Lucky for me, I turned it off, turned it back on and it started, but that one concerns me a lot. That appears to be a "You can't fix that on the side of the road" thing.

Code 12 - No normal signals received from crankshaft position sensor.
It would be very rare that would fail, if ever. I call it a fake code. Sometimes the ECU gets confused, ignition reset will do it. Clear the code and see if it comes back. It shouldn't happen maybe once in a blue moon. When you start the bike, let it go through the full initialization sequence (self checks), fuel pump cycles 2 seconds and shuts off.... now start it.
Have you done a valve check recently by chance, had the battery disconnected or playing with anything else?

raYzerman wrote: ↑Tue Oct 06, 2020 7:57 am Have you done a valve check recently by chance, had the battery disconnected or playing with anything else?

Nope, haven't touched it. I hope it's just a one time hiccup. I drove it to breakfast, it started fine, ate breakfast, and went to start it and it got the code. Turned it off and back on again and it was off and running.

To revive this thread....... so the TPS has been replaced and the problem still exists... and now we suspect the APS?

I have another '13 owner with what he called a "surge", but turns out he throttles up to 2000 and it shoots up to 4500, after which he can throttle up normally.. I call that a "jump" rather than a surge..... I'm thinking APS replace. He has not done TPS, and I don't think TPS normally causes that....

I think Viper Dad's is a surge. You hold the throttle steady and it buck jumps.

Still don't know what the acceleration sensor is.

That jump is a diff symptom than a surge.