Accelerator Position Sensor (APS) Adjustment

[1moreroad]

Did it this afternoon.  Thanks @piotrek.  Based on everyone's experience, I dialed it back 3.

DIAG 14 OLD - 17 101 NEW 14 98

DIAG 15 OLD - 17 99 NEW 14 97

I'd say it's 50% better.  I rode a couple of miles in 1st gear whacking the throttle open and closed.  I feel like I can be more aggressive with the throttle but still smooth.  It should be easier to ride twisties.  A mode feels a little smoother than STD used to.  B mode makes noise but feels VERY sluggish to accelerate.

I have the Australian wire harness installed (sets off idle fueling higher), but not a flash.  This tweak is as big a revelation as that harness.

It's 95 degrees and I already spent all morning outside, so I was getting very hot standing in the unairconditioned garage so I couldn't iterate the process.  Maybe I'll try again when the weather is cooler.

Question - what are we adjusting?  Is it tied to the spring to the left side under the tank?  Is it an inertial unit?

[betoney]

2 hours ago, 1moreroad said:

Did it this afternoon.  Thanks @piotrek.  Based on everyone's experience, I dialed it back 3.

DIAG 14 OLD - 17 101 NEW 14 98

DIAG 15 OLD - 17 99 NEW 14 97

I'd say it's 50% better.

Question - what are we adjusting?  Is it tied to the spring to the left side under the tank?  Is it an inertial unit?

After I initially adjusted mine, there was a very noticeable difference, I decided to adjust it again dropping the settings down to 12, even smoother.  Next time you are under the tank, give it a try.

I'm not sure exactly but I believe the adjustment affects the ratio or speed between the throttle grip turning and the throttle bodies opening.

[piotrek]

On 7/18/2020 at 6:10 PM, 1moreroad said:

Question - what are we adjusting?  Is it tied to the spring to the left side under the tank?  Is it an inertial unit?

The throttle cable spring that you note is mounted on a shaft that is coupled to the APS (basically a potentiometer). As you twist the throttle, the value that the APS reports to the ECU gradually changes. The ECU then adjusts the air-fuel mixture accordingly.

Edited July 21, 2020 by piotrek

[betoney]

@1moreroad - This is the best explanation I could find, from the sensor manufacturer. 

APS or Accelerator Position Sensor | Asahi Denso Co., Ltd. - The special maker for Human and Machine Interface -

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A sensor that measures the amount of accelerator operation is called an...

 

[iitywygms]

On 7/18/2020 at 5:38 PM, betoney said:

After I initially adjusted mine, there was a very noticeable difference, I decided to adjust it again dropping the settings down to 12, even smoother.  Next time you are under the tank, give it a try.

I'm not sure exactly but I believe the adjustment affects the ratio or speed between the throttle grip turning and the throttle bodies opening.

Would it be safe to say you turned the aps counter clockwise about 1/8 inch?  

[betoney]

45 minutes ago, iitywygms said:

Would it be safe to say you turned the aps counter clockwise about 1/8 inch?  

It has been a few years but I remember that I didn't move it much, on the '15 and '16 you could bring up a diagnostic screen and watch the value numbers change as you slowly turned the sensor.  It didn't take much movement at all, so yes, your assumption sounds very close.

[iitywygms]

12 minutes ago, betoney said:

It has been a few years but I remember that I didn't move it much, on the '15 and '16 you could bring up a diagnostic screen and watch the value numbers change as you slowly turned the sensor.  It didn't take much movement at all, so yes, your assumption sounds very close.

I wonder if I were to wire up an obd reader as described on this forum if you could read the aps numbers using the torque app. 

Something I will try in the future.

 

[skipperT]

14 hours ago, betoney said:

@1moreroad - This is the best explanation I could find, from the sensor manufacturer. 

APS or Accelerator Position Sensor | Asahi Denso Co., Ltd. - The special maker for Human and Machine Interface -

---

A sensor that measures the amount of accelerator operation is called an...

 

Yes, if you scroll down to “Electronic method: Satellite method”, that is the closest explanation to how Yamaha does it (YCC-T, or Yamaha chip controlled throttle).

nice find, @betoney

-Skip

Edited July 21, 2020 by skipperT

[Wintersdark]

On 7/13/2020 at 8:16 AM, betoney said:

It "might" be possible but not in the same way that you could on the '15-'16.  On the early models you could go into a diagnostic screen on the dash and watch the values change, with the new models you more than likely need a scan tool.

Yeah, but it bears noting that the scan tool in question is actually very inexpensive.  A basic handheld scan tool and adapter is like $30 on ebay, or as I posted elsewhere you can use a bluetooth dongle and adapter.  

 

That said, the scan tool gives you APS percentages, but the service manual specifies specific numbers that you won't see unless you use the proper Yamaha Diagnostic Tool, which is stupid expensive. 

[Dardarstar]

On 4/4/2017 at 6:08 AM, piotrek said:

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.
 
 
 
 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):
 

 

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...
 

 
Physical position of the APS... before and after.
 

hi there, 

i have a question please. 

can i do the check only for the values on my bike without openning nothing? only by following the proceedures to get to Diag14 and Diag15? it seems that i don't need any special tool only for check the values. i understand that for adjusting the aps i'll have to open up. thanks in advance for your answer.

 

 

[betoney]

@Dardarstar - Yes, if you have a 2015 - 2017 model, you can access the diagnostic screen without a code reader/scan tool. 

If you follow the steps 1-7 that you quoted above, it will show you the current values.  You only need access under the fuel tank if you want to make any changes.

[Dardarstar]

Thank you so much!

[piotrek]

Probably something the owners of legacy FJs with MCCruise already know... but just wanted to reiterate the need to re-calibrate the CC after making adjustments to APS. I left this simple task for another day, and then of course forgot to do it. Definitely a safety issue as the engine ends up surging. Lesson learned.

I am not sure whether the 900/GT owners would run into similar issues after making adjustments on their bikes. Food for thought though... note your starting values (if/as possible).

[peteinpa]

I'm still not quite happy after my ECU flash on my 15 after several rides.

Checked my current settings and have:  14:  17 and 102      15:   16 and 99

With them so high I should get it really smooth when done dropping to the 10 and 12 #'s..

Guess I'll rip it apart again for the umpteenth million time. 😡

[maximo]

57 minutes ago, peteinpa said:

I'm still not quite happy after my ECU flash on my 15 after several rides.

Checked my current settings and have:  14:  17 and 102      15:   16 and 99

With them so high I should get it really smooth when done dropping to the 10 and 12 #'s..

Guess I'll rip it apart again for the umpteenth million time. 😡

I had this done at the shop after my ECU flash, and I don't recall what numbers we landed on, but I'll tell you, this mod is the single best thing I've done for my '15.  It was practically unrideable before, and now, while not buttery smooth, is good enough to ride. Keep at it!