TP Sensor adjustment

Its been discussed on here before about setting the -coo on the 1250, was wanting to know from the tech guys on here by setting that cursor  -coo to the top of the coo would that tell the ECU that the throttle is slightly more open than what it is because as you open the throttle with that on the dash it goes up to that spot and therefore tell the injectors to deliver slightly more fuel through the rev range, all the bikes ive adjusted that have been out, eg; cursor at the bottom of the coo have run better, ive now removed my secondary butterflys and that with the yoshi exhaust and the snorkel removed from the airbox lid have a very slight hesitation you could call it, around 2400 to 2600 not bad but i can notice it, and here is the problem in order to get the cursor to sit at the top of the coo you have to drill out the holes slightly as it wont stay there when i tighten the screws jumps back to the centre, havnt taken it for a ride as yet but will do that soon, any thoughts on what ive mentioned

I dont know adjusting the tps would help that..if youve done those mods it may pay to look into an efi controller i have asked similar questions.. and by letting more air into the motor without the right a/f ratio you may be causing the bike to run too lean? Im not an expert thats my opinion tho

mstrrab1992 wrote:I dont know adjusting the tps would help that..if youve done those mods it may pay to look into an efi controller i have asked similar questions.. and by letting more air into the motor without the right a/f ratio you may be causing the bike to run too lean? Im not an expert thats my opinion tho

Guess ill have to test out what ive done on the road before i go down the EFI controller path

I'll prefix this with "I am not a mechanic" and only have gathered the info below from reading it off different forum sites, however it does make sense to me.

I remember reading on the TWT site that this adjusting the sensor assembly on the side of the throttle bodies is in fact not the correct TPS adjustment, it is actually not setting the TPS at all, and in fact could be causing more problems than if you had not touched it at all.



The theory is that the sensor is not suppose to move, it is the throttle shaft that you want in the correct position.  Sort of makes sense, if the sensor is saying the shaft is out, i.e.   _C00  or   ¯ C00, by moving the sensor to ─C00 we are just setting a false reading as the throttle shaft has not actually been moved.  But by leaving the sensor in it's factory set position and adjusting the shafts position you can get the true middle line reading.

The actual TPS adjustment (item 17 below) is a real biatch of a screw in the middle between and under the two throtlle bodies, and the adjustment can only be done properly with the bodies of the bike.  Some have said that item 17 is the idle adjustment screw, however the manual itself states the idle adustment is an ECU parameter, not a manual adjustment.  



Beware there is another screw adjustment (item 18) above this one that is shown, that is for balancing the two throttle bodies and should not be touched as it is set by the factory.



So, with a lot of our members having set their TPS readings by moving the sensor body, has it been done it wrong ???

Good point barry.

Set it to coo- and buy a fuel controller and get it tuned professionally.  Fuel injection is meant to be easy, trying to fudge it by moving sensors etc is going to get you into hot water. Do it properly.

reddog wrote:Set it to coo- and buy a fuel controller and get it tuned professionally.  Fuel injection is meant to be easy, trying to fudge it by moving sensors etc is going to get you into hot water. Do it properly.

But thats exactly what you are doing with a fuel controller tricking the ECU into thinking its controlling the fuel system, blocking the Co2 sensor in the exhaust and piggy backing the injector plugs, im just trying something different thats very easily put back to standard before i go down the controller path,
thanks barry_mcki for your comments and detailed view which i agree, but what tells the ECU the position of the throttle shaft, it would have to be the sensor which lets the ECU know how long to open the injector for, i may be totally off the mark here but will see what happens with a good ride to test it out

But the efi controller will give it more fuel where its ment to not possibly fuel where it may ne needed which is what would happen if you were to adjust the sensors

Having thought about it a bit more the method of moving the sensor module can be justified but only if the throttle is fully closed.  Once the ECU knows the position of the throttle shaft via the TP sensor voltage it can do its thing and pulse the injectors accordingly.  However, if this sensor information is not properly aligned with the butterfly positions then the ECU would be thinking the air intake is at one level when in reality it was something else.

So, as long as the throttle shaft has all the butterflies completely shut, then the TP Sensor should read  ─C00, if it doesn't then a small adjustment of the sensor body should bring things into alignment.  

However if the shaft is not fully closed then the screw adjustor (item 17 above) would need to be made and more than likely a realignment of the sensor body as well.

BTW the workshop manual gives a readout of the TP sensor for fully open and closed conditions:

barry_mcki wrote:Having thought about it a bit more the method of moving the sensor module can be justified but only if the throttle is fully closed.  Once the ECU knows the position of the throttle shaft via the TP sensor voltage it can do its thing and pulse the injectors accordingly.  However, if this sensor information is not properly aligned with the butterfly positions then the ECU would be thinking the air intake is at one level when in reality it was something else.

So, as long as the throttle shaft has all the butterflies completely shut, then the TP Sensor should read  ─C00, if it doesn't then a small adjustment of the sensor body should bring things into alignment.  

However if the shaft is not fully closed then the screw adjustor (item 17 above) would need to be made and more than likely a realignment of the sensor body as well.

BTW the workshop manual gives a readout of the TP sensor for fully open and closed conditions:

guess i was hoping someone had tried it and said it doesnt work, ill let you know if it does or doesnt

Seriously good post Barry, I'm trotting straight off to the Texans to catch up.

(PS While working through your first post an old phrase about cats and winged rats came straight to mind. When the illustration scrolled into view I cracked up.)

Are you checking the TPS  when at operating temp, just asking because on other bikes I have done this is standard procedure as stated by the workshop manual.
Case in point is my SV650 (which I'm now selling), when cold it reads _C00 yet when warm reads -C00 and thats when I adjust it, and yes you do move the sensor and not the throttle blades via the throttle stop screw.