Suzuki TPS

GSX-S TPS Adjustment

 GSX-S TPS Adjustment

One of the few issues with the Suzuki GSX-S1000 is the snatchy or jerky throttle response and one change that can go a long way towards curing this is setting Throttle Position Sensor.  On a number of motorcycles it seems to come from the factory with the Suzuki GSXS TPS incorrectly set.  TPS setting can make an enormous improvement to your motorcycle. Early bikes have an indicator but TPS Voltage is more accurate and TPS Voltage can be set on all Suzuki GSXS.

The Suzuki GSXS TPS comes with a white painted TPS check alignment mark which seems to be off on most bikes, it should be aligned exactly, but don’t set it using the white mark – it is not accurate enough to set the Suzuki GSXS TPS, but after adjusting it correctly using one of the methods below the Suzuki TPS white marks may be aligned, but don’t worry about it.

Why adjust TPS

 

TPS has one and only one job! To tell the ECU exactly how far open the mechanical throttle is. ie closed, or a % open all the way to WOT and it does this by giving a voltage feedback to the ECU at different throttle positions.

If it is set too high (rare) then the bike will never reach an idle state as the ECU will think the bike never has a closed throttle. (This is why if you set TPS too high you can’t adjust TC as this needs to be done with a closed throttle). eg Idle should be 1.11 to 1.14V, If its set to 1.2V the ECU will never get the 1.14V signal and thus the bike will never be in a closed throttle state. The Voltage will also be be wrong at every other point on the MAP giving the wrong information the the ECU and thus will never run exactly as it should, although this will be less sensitive the more the throttle is opened (we all know there is less difference between 90 and 95% throttle than 0 and 5% throttle)

If it is set too low, then the throttle will open a bit with out the ECU registering that the throttle has opened and then when the throttle is opened even wider the TPS registers that its open and suddenly tells the ECU to add fuel giving the snatchy throttle, eg, the TPS is set at 1.08V, the bike knows it got a closed throttle as it is less than 1.14V so idles fine, when you open the throttle a little allowing more air into the engine the ECU may still be only getting less than 1.14V so doesn’t change the fuelling, then as it opens further the bike suddenly adds more ignition advance, opens the STPs more and adds fuel giving the a sudden increase in power causing snatchy throttle.

A flashed ECU with smoother fuelling etc may mask some of the symptoms but does not cure them. Its a computer and that Famous Synonym GIGO (Garbage In Garbage Out) applies, if you are giving the ECU the wrong information how can you expect It to give the correct results (ie for the bike to run as it should)

The learned value is an offset that the bike will learn to adjust the voltage to affect for error, but from what I understand is very limited. So if you ECU has an offset of -0.03V and you set your TPS to 1.13V the ECU will read 1.10V unless you reset the learned value back to zero.

So TPS should in my opinion be done first and in particular if you are having your bike flashed and dyno tuned set the TPS initially or you will be tuning for the incorrect inputs to the ECU

 

 

Update – Video on Suzuki TPS adjustment at the bottom of the page

 

Suzuki TPS setup
Suzuki TPS White mark

There are 2 ways to set the Suzuki TPS, using the dash markings or a voltmeter, the latter is more accurate but the former is usually close enough.  For the dash method you need to use the Suzuki special tool, below or a short piece of wire (or paper clip etc.)  On the 2017-18 models the GSXS TPS can only be set using the voltage method as the dash marking don’t appear to help in adjusting TPS.  Before adjusting the TPS the fairings must be removed and the tank lifted, see here for instructions.

TPS Learned value

The ECU stores an offset value for the TPS called the learned value, this offset should be reset after adjusting or replacing the TPS (it there to allow for voltage drift over time).

This can be reset by Suzuki SDS, Healtech OBD, or Woolich racing software.

Adjusting TPS with dash

The image below shows how to put the Suzuki GSX-S in to DTC or Dealer mode.  The Dealer mode or SDS connector is under the pillion seat on the right side of the bike (sitting on the bike) using a special tool, alternatively just link the bottom two terminals in the connector.

Adjusting TPS with dash

Alternatively If you don’t have the special tool, just attach a piece of wire or paper clip between the two lower terminals (marked in red below) on the connector under the pillion seat.

Suzuki GSXS Dealer mode location

 

Then adjust the TPS to get the line to line up in the centre as highlighted in red above.  Lift the tank and find the TPS on the right hand side (looking from the rear), disconnect the STP (Secondary Throttle plate) sensor temporarily and use a T25 security torx bit to release the TPS and adjust by levering it against the head a tiny bit at a time with a largish flat screwdriver, a tiny movement makes a big difference, until the lines are aligned, with a little throttle it should move to the upper line.  Once adjusted the on-off throttle transition should be much smoother.  If you adjust too far you will not be able to adjust traction control settings so check you can still adjust the traction control before replacing tank and fairings.

T25 Torx  security bit, (also none as Torx Tamper resistent TR25)  note the hole for the pin in the centre – not a usual T25 bit

Torx TR25

T25 vs TR25 Security torx

 

 

Blue is STP connector, needs unplugging to get to torx bolt.

Red is the Torx T25 bolt that locks the TPS in place

Yellow is the TPS connector that needs to be unplugged and connect to break out lead if using voltages for TPS setting.

GSXS TPS setting
GSXS TPS Location

TPS Voltage setting

The better alternative is to use a special tool that allows you to measure the voltage read at the TPS.  The Suzuki part no. is 09900-28631 but the Kawaski part is identical and cheaper and can be used to adjust the Suzuki TPS setting, Kawasaki Part Number is 57001-1538.  This is attached to between the TPS and its connector and has 3 break out connectors.  After adjustment the painted white lines should line up.

Use a largish flat screwdriver to gently lever the TPS here once the torx bolt is released

Adjusting GSXS TPS seting
Adjusting GSXS TPS
Kawasaki Suzuki TPS breakout Lead
Kawasaki TPS breakout Lead

Breakout Lead 

Kawasaki Part Number – 57001-1538

Suzuki Part Number – 09900-28631

Use the breakout lead as below, the voltage with the engine fully warmed up and idling should be between 1.10 and 1.14 Volts, best results at 1.13V

 

Suzuki GSXS TPS breakout lead instructions
TPS breakout lead instructions

 

TPS Breakout lead

Suzuki GSXS TPS Adjustment Video

 

 

 

 

Secondary Throttle Sensor adjustment

Suzuki STP setting