Yzf 450 Tps Sensors

7 replies to this topic
  • shade

Posted August 05, 2006 - 09:55 AM


Does Any One Know The Effect Of Leaving The Tps Unhooked .does The Cdi Go To A Default State????????? This Is A 04 Bike


Posted August 05, 2006 - 11:19 AM


Why would you leave it unhooked?

  • shade

Posted August 05, 2006 - 11:54 AM


my bike has had a miss when you hold a steady throttle since i got it new about 3 months ago.it does it at any rpm . it seems better with the tps unhooked.

  • Satch0922

Posted August 05, 2006 - 12:25 PM


Here are a couple of threads you can read about TPS

TPS Thread

TPS Thread #2

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  • shade

Posted August 05, 2006 - 05:04 PM


thanks a lot for the tps info.i had been telling my friends it helped and they thought i was a idiot. :thumbsup: :ride: :applause: :applause:

  • aford541

Posted August 05, 2006 - 09:17 PM


I disconnected mine on the 03, 04, 05 bikes with much success.

  • grayracer513

Posted August 06, 2006 - 08:24 PM


The TPS is the electronic equivalent of the vacuum advance on a car. The CDI unit uses it to adjust ignition timing based on engine load. It also use a "tach" signal from the ignition to determine how fast the fast the engine is running, and adjusts according to that as well. That gives the ignition the "3D" timing map that you hear about. It electronic terms, it's often spoken of as if it were a new thing, but in truth, cars have had it for well over 50 years by using a centrifugal advance in combination with a vacuum advance in their distributors.

The part that people often don't understand is that engines need, and TPS's and vacuum advances provide, MORE advance during part throttle operation. The engine needs this in order to get the most power out of the small amount of fuel being delivered while cruising. The dynamic compression in the engine, the "real" compression, if you will, is also much lower, because the source of air to compress is throttled back so far, and that begs more ignition lead as well. Full throttle performance is not affected by a vacuum advance or by the activity of a TPS, because at full throttle, such devices no longer add more timing. However, cruising performance and other part throttle situations may suffer a little.

To the original question of how the CDI responds to the TPS being disconnected, the unit will do one of 3 things:

> Since TPS's are pretty universally set up so that the output voltage is low at full throttle, the unit will see the absence of any TPS output simply as the engine always being at full throttle and adjust the timing based on RPM alone. This appears to be how the Yamaha CDI deals with the issue.

> See the zero TPS output as a fault, and enter a default "limp home mode". How this will affect timing will vary considerably with the manufacturer.

> A combination of the above two.

I haven't disconnected mine, and I probably won't. Maybe I should try it. But mine doesn't have the sag/hit thing at 8000 because the Power Bomb header makes it go away, so I don't need a cure for that anymore.

One thing is for certain, no one will be disconnecting TPS's when EFI comes out.

  • shade

Posted August 08, 2006 - 05:48 PM


I Understand Your Point.thanks For Taking The Time To Hit Me Back.i Bought This Bike About Two Months Ago New,leftover.this Was My First Thumper So I Didnt Know What To Expect.after A Couple Of Days I Realized It Had A Miss At Steady Throttle,any Rpm,worse At High Rpms.i Unhooked The Tpi And Noticed It Didnt Miss As Bad.i Have Done Everthing To My Jetting ,nothing Helps.i Have A Yfz450 Also And It Runs Clean.i Have Ordered The Non Us Needle And Jets And Am Hoping This Will Help.some People Say It Is Rich But I Have Really Leaned The Main And Pilot And It Still Does It.i Am Pulling What Left Of My Hair Out.later

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