TPS - is it worth fixing?


8 replies to this topic
  • Adammoto

Posted November 12, 2009 - 09:10 AM

#1

I have spent a lot of time in the garage already trying to figure this out. Will someone who has been though the TPS problem before please point me in this right direction?

Disconnecting the TPS significantly reduces a rough running condition at 1/8 to 1/2 throttle or so under light loads on my 09 YZ450F. The question is what to do about it. I prefer the feel of the motor with the TPS connected, but fixing it sounds like a major PITA. From what I have been reading, people approach the faulty TPS from a number of angles. Do I need to adjust the TPS, buy a new TPS, replace the CDI, or all of the above?

Here are the resistance measurements I took last night:
Resistance blue-black (static): 4,220 Ohms (within spec)
Resistance black-yellow (dynamic): 500 closed, 3.66 open Ohms (not quite within spec).

If this is a wild goose chase I'd rather just live with it. Thanks for any help on this one!!

  • grayracer513

Posted November 12, 2009 - 09:31 AM

#2

At 3660 Ω, you're pretty close, and your problem may be a simple adjustment.

You might first see if heat significantly changes the readings you get. It shouldn't change by more than 5% at operating temps.

After you have verified the resistance readings are stable and consistent, do the adjustment check on 6-6 - 6-7 of the manual (sensor output voltage while running at idle). It may be out of spec, and that could correct the problem.

IF it needs to be adjusted, loosen the mounting screw enough to allow the TPS to be pivoted on its mount while running by tapping on the mounting flange (prudently) with a small punch. This will make it much easier to dial in, and cut the number of times you'll need the carb on and off.

  • Ga426owner

Posted November 12, 2009 - 09:50 AM

#3

agree try to adjust the TPS position first, but only after you notch the stock (from Factory)position on the carb body and the tps sensor. You will need to know the exact stock position if it all goes to heck and a handbasket...
The changing the TPS Sensor position may possibly adversely affect the static (within spec)reading to get the dynamic into spec. You will only make the slightest movements of the TPS from each side, left or right of the notches and get the settings each side with the meter.
If you can not get both within spec - my assumption, Grey correct me, is that the TPS will need to be replaced.

  • grayracer513

Posted November 12, 2009 - 10:11 AM

#4

The changing the TPS Sensor position may possibly adversely affect the static (within spec)reading to get the dynamic into spec. ...
If you can not get both within spec - my assumption, Grey correct me, is that the TPS will need to be replaced.

I'd say that, yes. Also, in reading the resistance between open and closed, run the sensor through its whole range slowly and watch for any sudden dips or spikes in resistance, which would indicate faulty spots on the sensor track.

Visit the ThumperTalk Store for the lowest prices on motorcycle / ATV parts and accessories - Guaranteed
  • Adammoto

Posted November 12, 2009 - 10:28 AM

#5

I'd say that, yes. Also, in reading the resistance between open and closed, run the sensor through its whole range slowly and watch for any sudden dips or spikes in resistance, which would indicate faulty spots on the sensor track.


Do you mean watch for spikes in resistance when rotating the throttle or when rotating the TPS with the throttle closed?

I'll try that and the sensor output voltage test tonight...then take stab at adjusting it if necessary.

Thanks for the reponses.

  • grayracer513

Posted November 12, 2009 - 10:37 AM

#6

If you have the sensor in your hand, then rotate it by hand. If it's on the carb, just run the throttle through its full range as you read the resistance.

  • Adammoto

Posted November 12, 2009 - 04:19 PM

#7

I did the output voltage test and got .76 volts (the upper spec is .78). Also did the dynamic test looking for spike in resistance and it appears to be operating smoothly. So basically the thing is working right aside from slightly low resistance at full throttle. Now I am even more confused...I thought I had it diagnosed. Any suggestions?

  • grayracer513

Posted November 12, 2009 - 04:29 PM

#8

If you feel like experimenting, advance the TPS slightly toward the lower limit of output. See if the upper and lower resistance limits can be brought into spec without going lower than minimum output voltage. Then see how it runs.

You may have a problem that a needle with a differeny upper diameter may cure.

  • Adammoto

Posted November 12, 2009 - 04:38 PM

#9

I tried the NFLQ needle (richer straight diameter) and didn't notice a difference. I'm at 5,000 ft. in Colorado so the richer needle seemed strange, but others had success with the NFPP. Anyway no noticeable improvement for me.

Guess I'll try experimenting with the output voltage.





Related Content

Forums
Photo

Chubby dad, looking at bikes , First trip to the orange/black forum ! by Slow_ride


Dirt Bike   Make / Model Specific   KTM   250-530 EXC/MXC/SXC/XC-W/XCR-W (4-Strokes)
  • Hot  28 replies
Forums
Photo

Snake pit oct 30th by The Anvil


Dirt Bike   Dirt Bike Regional Discussion   California
  • Hot  293 replies
Forums
Photo

James Stewart back on a YZ450F by YamaLink


Dirt Bike   Special Interest Forums   Pro Racing
  • Hot  47 replies
Wiki
WR Camshaft Swap Info - last post by jamesm113

WR Camshaft Swap Info


Articles
  • 0 replies
Forums
Photo

Michigan Motocross Tires by 288yz450


Dirt Bike   Dirt Bike Regional Discussion   North
  • 1 reply
 
x

Join Our Community!

Even if you don't want to post, registered members get access to tools that make finding & following the good stuff easier.

If you enjoyed reading about "" here in the ThumperTalk archive, you'll LOVE our community. Come join ThumperTalk today!

The views and opinions expressed on this page are strictly those of the author, and have not been reviewed or approved by ThumperTalk.