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piotrek

Accelerator Position Sensor (APS) Adjustment

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IMPORTANT NOTES:

  • This procedure involves adjusting a component in a throttle-by-wire system. Do this at your own risk. See Service Manual Page 7-12.
  • MCCruise cruise control owners.. you will need to re-calibrate your cruise control system after making changes to the APS.

I checked and adjusted the APS yesterday. It is very much possible to do with just the rear of the tank raised (as far as it will go), with plenty of space to work with, if you have the right tool. I sacrificed an 8mm 1/4" drive socket (5/16" socket works too), a 7/32" hex key (or whatever key will fit) and a piece of flat metal something (I used a vise to press it in) to make the tool. Worked like a charm.
 
  5182840.jpg
 
 The idea is to adjust the physical position of the APS to make sure the diagnostic readout lands inside multiple sets of value ranges, two for DIAG 14 and two for DIAG 15 (I understand the two are used for redundancy, since this is a throttle-by-wire system). Make sure to make note of your stock values before you loosen the APS bolts, then loosen them just so you can rotate the APS with a bit of force... not loose.
 
First, getting into the diagnostic mode (start with ignition in OFF position):
 
Capture.jpg
 

  1. On the dash display, press "TCS" (1)  and "RESET" (2) buttons together, and turn the ignition key to ON... and wait about 8s until "SELECT" + "ECU" show on the display.
  2. ]Press "TCS" and "RESET" buttons together again for about 2s, until "DIAG" shows on the display.
  3. Press "TCS" and "RESET" buttons together again for about 2s, until "DIAG" + "DATA" show on the display.
  4. You are now in the diagnostic mode, and you can switch through "DIAG" modes by pressing the "TCS" and "RESET" buttons.
  5. Keep toggling the "TCS" button until you get to "DIAG 14". The "DATA" value displayed will be the value you'll be adjusting with the APS.
  6. When done with "DIAG 14", toggle the "TCS" button and go to "DIAG 15".
  7. To leave the diagnostic mode, turn ignition to OFF.

In DIAG 14, adjust the APS output with the throttle closed (rotating the sensor clockwise increases the value), and then open the throttle fully and check that it's still within the required range. I adjusted for the position that landed at the lowest possible value at closed throttle, but still inside both ranges. The lower the DIAG values, the smoother the throttle is supposed to become as you open it from the closed position.
 
In DIAG 15, do pretty much the same thing... but of course the range of adjustability will be limited by what was done in DIAG 14, which is why the manual tells us to go back and forth between DIAG 14 and DIAG 15... to check that we're still inside the ranges for both DIAG modes.
 
Tighten things up, and double-checked the readings. My test ride didn't reveal any miracles, likely because the stock figures weren't that much different. Yours may be different, so it's worth checking and adjusting if needed.
 
My results...
 
Capture1.jpg
 
Physical position of the APS... before and after.
 
5182913.jpg

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canada.gif.22c5f8bdb95643b878d06c336f5fe29f.gif - IBA #66956 - 2015 Yamaha FJ-09

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I too got the same information from Nels at 2WDW when asking about abrupt on/off throttle.
 
"...What we found from testing is that even though the APS is in "factory specification", turning it back 3-4 degrees will fix the problem. You can loosen up the two screws that hold the sensor and turn it counterclockwise about a 16th of an inch. Just ever-so-slightly turn it back. There is an actual procedure to follow using the diagnosis mode. The factory specifications are "between 10-23" factory is usually set to 17. We have turned them back to 13 and that's all it took. This will make the throttle less aggressive but will not affect any of the top end. This has worked wonders on the FZ09"
 
I will finally get around to trying this out on my next day off.

***2015 Candy Red FJ-09***

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"My test ride didn't reveal any miracles, likely because the stock figures weren't that much different."
 
That's why I think there is a bit of guessing how far to adjust the APS, there are other factors involved making every bike a little different, maybe you need to adjust it more. The bottom line is adjust to suit your preferences,  use numbers only as a guide.
 
Good write up.

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If I remember correctly, the value on the dash gauge for idle was 16 and would not go below that regardless how far I moved the APS. The values for full throttle were on the low side of the range in the chart and would not go any higher. I suspect that the 2015 and 2016 model years had defective APS sensors. Or maybe there was some other adjustment that affected the numbers, I don't know enough to know. But it is interesting how the complaints of snatchy throttle syndrome have gone down to almost nothing recently.
 
At this time, my best guess set the idle numbers correctly, or at your preference, and then check to make sure you can get the upper ranges of numbers at full throttle. This may be to check you are getting full movement of throttle plate from idle to full throttle. But someone else with more knowledge of this FI system will have to verify that.
 
I have completed several more rides, and my throttle feels like described above, softer throttle response at lower throttle settings, but seems to have same power at full throttle and higher RPMs. My throttle control has improved dramatically and I have no intention to make any more adjustments even if the numbers on the gauge are not correct.
 
 
I did not hear any relay buzz, but maybe my hearing is not good enough to hear it.
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Well, I just got back from my test ride after adjusting the APS and am happy to report the change is VERY noticeable! As Nels indicated, adjusting the value back just a few digits is all it takes. Mine was 17 and I dropped it to 14, its simple enough to do I might try 13.
I tried it in STD and A modes and A just has the slightest abrupt transition from on to off or off to on throttle, but STD is absolutely seamless, almost electric feeling.
To anyone considering this, do as Piotrek did and write your values down before you touch the APS so you have a starting value, then adjust it back 2-3 digits at a time. If you dont like it, simply change it back.

***2015 Candy Red FJ-09***

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@betoney ... with 14, were you still in range for all else?
Yes I was.  Closed throttle was 14 and WOT was 98.  Diag: 15 was Closed:15 and WOT:99. Nothing wrong with making minor adjustments out of range, if you dont like the change, simply move it back, and best of all, ITS FREE!
 

***2015 Candy Red FJ-09***

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Note that piotrek, betaney, and myself all have slightly different reports of the effect adjusting APS. Piotec, not much difference, Betoney where STD mode is "seamless", and my report where I can now ride in A mode in all street riding conditions, seamless and electric also are accurate descriptions. This supports my theory that you need to find the position that works best for you, and at lower numbers than when you started.
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Hey Piotrek, the ECU reflash not quite do the trick or are you like me and tend to tinker for the sake of tinkering...hence the forum name blessed upon me by my wife.
 
Cheers
 

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The flash did a decent job on STD-mode, but... although improved, still a little snappy in A-mode.
My findings exactly.  STD was almost on the money after the flash, but A-Mode was still a bit too abrupt for my liking, and that was my main focus.  Moving it back a few digits was a noticeable improvement. 

***2015 Candy Red FJ-09***

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Hey Piotrek, the ECU reflash not quite do the trick or are you like me and tend to tinker for the sake of tinkering...hence the forum name blessed upon me by my wife. 
Cheers

The flash did a decent job on STD-mode, but... although improved, still a little snappy in A-mode. No big drama, but APS looked like the next logical step (based on forum feedback) that didn't cost anything. That second part... that's me too. I keep telling my tribe... ya better start writing some of this stuff down, for when I go.... you're all screwed!  :P
Good to know. I put in the Kev mod and will see if that tames things but I will have to wait and see if it works as I am still waiting for my suspension components to come back, it may be a while. They better show up soon or my trip plans will be hampered. 

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I'll definitely be giving this a try soon. Thanks for the write up. Will update with my results.

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Wow, It really works!
Thanks for the instructions and pics. Nels mentioned this procedure to me a year ago when I told him that my FJ was still lurchy after his flash with off and on throttle applications, but it sounded tricky, and I did not know exactly what to look for or how to do it.
 
Your post gave me the confidence to do it a couple of days ago and I have about 80 miles on it, and the difference is major. The snatchy throttle has been the one thing keeping me from really loving this bike for almost 2 years. I took the values down to at or near the bottom of the range you posted(where did you get that info from?). I don't have my notes right now, but I put them at about 11-96. Standard mode is smooth and it is now easy to go from off to on throttle on corner exits with now upsetting jerkiness. A mode is smoother than it was but still a bit jerky if I am nor careful. It is great to be able to ride with my wrist and forearm not tensed up, trying to be so careful to not get that lurch.
 
I wonder what going even lower would do for the performance. What is actually happening in there when you turn that plastic housing? I wonder if you could lean out the mix or something, and cause any damage.
 
Anyway, I am off on a 4 day trip of spirited riding with good buddies tomorrow. Really looking forward to it now. Thanks again, piotrek!

Pistons or pedals, 2 wheels are where it's at...

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I wonder what going even lower would do for the performance. What is actually happening in there when you turn that plastic housing? I wonder if you could lean out the mix or something, and cause any damage.

The APS is just one component used in engine air fuel mixture and throttle management.   From what I understand about FI, and I am no real expert, is that the ECU maps determine air fuel mixture, with oxygen sensor input in closed loop mode at low throttle settings and cold engine temps.  The ECU maps apparently are not changed by the APS.   
My guess is that the APS simply changes the signal to the ECU, effectively slowing the rate at which the throttle butterfly valves open as you twist the throttle open.  When the throttle valves open slower, the engine RPM/torque increase is slower, and snatchy throttle is smoothed out. 
 

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I think I left it at 12-97 in diag 14, and 11-96 in diag 15.
 
I heard servos and buzzing as I cycled through the other diagnostic parameters, but none while in 14 or 15.
 
You must have a service manual, because I found nothing about this stuff in the owners manual.
 
 

Pistons or pedals, 2 wheels are where it's at...

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I think I left it at 12-97 in diag 14, and 11-96 in diag 15. 
You must have a service manual, because I found nothing about this stuff in the owners manual.
 

I adjusted my closed throttle setting from 17 down to 14 in DIAG: 14 and it really softened the on/off throttle transition, if you adjusted yours further down to 12 it must be as smooth as B mode. 
 
Yes, the values are listed in the service manual, the procedure is Ch7, p14/15.
 

***2015 Candy Red FJ-09***

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