Is running with NO TPS causing me any power loss?


12 replies to this topic
  • bluebreadtruck

Posted January 05, 2009 - 05:35 PM

#1

I have been running my bike with my tps unplugged because when I try and use a voltmeter to set it correctly, the correct voltage spec is always about 90 degs off from where i would need it to be to screw it in.


So, besically what does leaving it unplugged leave me for a timing curve? Should I try and find a used TFS or new somewhere, or find a new way to set it not using voltage?

  • William1

Posted January 06, 2009 - 02:55 AM

#2

Not having it plugged in, you loose a little throttle response (crispness) but you gain steady throttle smoothness.

Might want to ensure the TPS tab is properly aligning with the throttle shaft.

I have been thinking about installing a switch for my TPS so I can enable/disable it on a whim. Would be real nice on a DS ride, TPS on in the woods, off for the transit portions.

  • 123BigcoopDawg576

Posted January 06, 2009 - 07:25 AM

#3

I have been thinking about installing a switch for my TPS so I can enable/disable it on a whim. Would be real nice on a DS ride, TPS on in the woods, off for the transit portions.


that has to be the best thing i have heard/read all day...:thinking:

i think i might look into this:ride:

  • William1

Posted January 06, 2009 - 08:07 AM

#4

Thanks. I have been thinking about it for some time. I just need to come up with a 'factory' install. I'll need to get a male and female set of those triangular plugs. I am assuming both the Yellow and Blue wires have to be switched so it will mean a double pole, single throw switch is needed.

Where to mount it... how to mount it.. hmmmmmm

  • 123BigcoopDawg576

Posted January 06, 2009 - 08:09 AM

#5

Thanks. I have been thinking about it for some time. I just need to come up with a 'factory' install. I'll need to get a male and female set of those triangular plugs. I am assuming both the Yellow and Blue wires have to be switched so it will mean a double pole, single throw switch is needed.

Where to mount it... how to mount it.. hmmmmmm


you figure it out test it report back and then ill try!:thinking:

  • William1

Posted January 06, 2009 - 08:30 AM

#6

I already have a switch on the Grey wire. Kind of handy in the real tight single track stuff to be able to soften the 'hit'.

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  • jams229

Posted January 06, 2009 - 08:35 AM

#7

I put my switch on the bar - left side. Plenty of room. But I find I use it very little. The difference is not as noticeable as I thought it would be.

  • William1

Posted January 06, 2009 - 10:26 AM

#8

Me too. Only when the sigle track is really, really tight does it make riding better. In the last year, I have ridden in only one place that made it worth it. I put mine in the airbox as it is a rarely needed function and the engine has to be completely switched off, though a bar switch could be used if you were coasting, shut off, fliped it and restarted. Me being so old and dumpy, it is an excuse to take a break. Plus, I cannot flip it accidently. It is fun though, when someone wants to 'check my bike out' and I leave it on the WR setting. They wonder why it is slowewr when they ride. I tell them is is all about finesse and skill.

  • grayracer513

Posted January 07, 2009 - 02:32 PM

#9

The function of the TPS is to provide information to the CDI about the load state of the engine. It uses this info, along with the engine speed, to change the ignition advance to suit the situation. Disconnecting the TPS is fundamentally the same thing as what the hot rodders did in the old days when they went to a mechanical advance distributor in place of the original mechanical/vacuum advance distributor. The engine looses its ability to change the timing according to load, and bases the advance curve solely on engine speed.

With the TPS off, the CDI sees voltage at the TPS input pin as being below the minimum level, and assumes that means full throttle. So, at full throttle, there will be little or no difference whatsoever in performance with the TPS out of the system. At part throttle, what you will get depends on how the ignition was originally mapped out. A YZ450 will typically not be as sharp and crisp at part throttle without a TPS as with one. On the other hand, some of the late WR's have a tendency to stutter at a light load, steady cruise with the TPS in place because their timing under those conditions is set up to reduce emissions (part of this is carburetion, too), and some find that disconnecting the TPS clears this up. In any case, the only time there should be a change at full throttle is if the CDI is capable of identifying the voltage as out of range, and then put itself into a "fail safe" or "limp home" mode of operation, under which the advance curve may be different from the normal full throttle curve.

  • jams229

Posted January 07, 2009 - 07:36 PM

#10

grayracer - I appreciate your explanation, even though I don't understand it!
I would like to disconnect the TPS due to the annoying stutter on the road, but I have heard that the negative effects on performance when off road are more pronounced. What do you think the negative effects are? Thanks - I appreciate your thoughts on this.

  • DS-WR450F

Posted January 07, 2009 - 09:39 PM

#11

I really like the idea of wiring in a switch. TPS off cruising down the road, and TPS on off road.

  • William1

Posted January 08, 2009 - 04:25 AM

#12

grayracer - I appreciate your explanation, even though I don't understand it!
I would like to disconnect the TPS due to the annoying stutter on the road, but I have heard that the negative effects on performance when off road are more pronounced. What do you think the negative effects are? Thanks - I appreciate your thoughts on this.


You loose a little throttle response and "crispness" when disconnected but gain steady throttle performance (no/less stuttering). Hence the desire to add a switch.

  • grayracer513

Posted January 08, 2009 - 02:22 PM

#13

Not having much opportunity to play with a WR, I don't really know. It should only affect part throttle, but it might do more. As far as I know, all you have to do if you don't like the results is to plug it back in.




 
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