TPS sensor bad???

[camlope24]

i have a 06 yz 450. It wont hold an idle so i adjusted the tps sensor but no change. so i then just unplugged it. no change. still wont hold an idle. dies at rest and while rolling through a curve. i suspect it to be the tps sensor. does anyone suspect this to be the problem? will just "looping" it to bypass it resolve the issue like on the old blasters clutches? or will by farting around like this create a problem and burn up the CDI?

thanks in advance

[grayracer513]

The problem was likely never the TPS. Disconnecting it does no harm to the system, but it does disable the ability to map ignition timing according to both engine speed and throttle position, so the CDI rolls over to a two dimensional map based on the assumption of full throttle and uses engine speed as its sole reference.

Now that you've monkeyed with it, it's going to be fun to get it set correctly again.

If you have an idle that will hold for a bit, then drops off and dies, and if set higher, never drops off, that's a "hanging idle", and it's generally the result of a lean condition, which can be caused by improper idle circuit adjustment, contaminated jets, air leaks, or tight intake valves.

[Ga426owner]

Curious how you adjusted the TPS Sensor? I have done this on my 06 and it is simply a huge PITA that takes tons of patience and some time and is prone to mistake. The smallest movement yield huge changes in the number of Ohms. What did you finally get to?

For anyone thinking of attempting to do this, save yourselves a lot of frustration and mark the sensor and the carb with a precise notch for the factory setting. This will save you tons of anger mgmt.

[grayracer513]

For anyone thinking of attempting to do this,...

...try to avoid it.

The actual adjustment process is outlined on page 6-10 of the manual, and involves back probing the connector to read output voltage at idle at a specific RPM. If adjustment is required, the carb must be at least partially removed, or a custom wrench must be made up.

Since your engine doesn't idle correctly, I'm going to have to say that you didn't do the TPS adjustment at all by the book.

[GCannon]

Do yourself a favor and get your idle speed and mixture set perfectly before you attempt to set the TPS

[Ga426owner]

...try to avoid it.?

The actual adjustment process is outlined on page 6-10 of the manual, and involves back probing the connector to read output voltage at idle at a specific RPM. If adjustment is required, the carb must be at least partially removed, or a custom wrench must be made up.

Since your engine doesn't idle correctly, I'm going to have to say that you didn't do the TPS adjustment at all by the book.

my point exactly, it is probably not set at the correct ohm level yet......AND YES AVOID THIS IF AT ALL POSSIBLE! Do not ever remove the TPS from the carb w/o making the position notch on both the sensor and the carb!

I made this mistake once and only once

here is the fun procedure:

The gas tank must be removed, you must be able to get the bike running for several minutes - yes w/o a gas tank, the carb has to be removed to a position to adj the TPS before finding the magic spot to tighten - it literally is hanging on. And you must be able to put the ohm meter in both of the correct positions to even get a true measurement that is right and not false.....and 7 out 10 tries gives different ohm levels....sounds like fun yet?

try it by yourself for even more fun....

[camlope24]

i havent moved the tps itself.. just the black turn knob bout an inch away from it.

[camlope24]

I should re-phrase my prevous post.. the bike will not idle (ever). at any temprature. I did do some back probing in the sensor and am only pulling half of the voltage that should be coming outta the tps. witch in turn makes me again belive a bad tps. i never moved the tps, just the black turn knob adjacent to it.

[grayracer513]

Knob? Do you mean the black knob shown here with the white "|\|" mark on it?

[Ga426owner]

i havent moved the tps itself.. just the black turn knob bout an inch away from it.

ah well that is a relief......

I think you are referring to the engine idle speed adjuster.....

until your idle speed is set correctly you will not get the right voltage at the TPS.

Search "engine idle" for tips on correctly setting the engine idle. You probably have it either too far in or too far out.

[grayracer513]

The thing is that the idle speed adjuster on an '06 isn't black.

The black knob is only the choke pull knob, and turning it does nothing but rotate the plunger. You're probably thinking of an old flat slide Keihin two-stroke carb that used the choke for the idle speed. Not so here.

In the second picture here:

https://www.thumpertalk.com/forum/showthread.php?t=696672

...showing the red aftermarket idle mixture screw, the idle speed adjuster is the silver slotted screw at 11:00 above the mixture screw.

Read also;

http://www.thumperfaq.com/jetting.htm#PJ

[camlope24]

its listed as the vaccum control knob...not the choke...tps was never taken off moved or adjusted either.

http://www.boats.net/parts/search/Yamaha/All%20Terrain%20Vehicle/2006/YFZ450V%20YFZ450/CARBURETOR/parts.html

i found it under google 2006 yfz450 carb diagram...

[camlope24]

thank you...i will try this

[grayracer513]

Using a parts fiche as a service guide is risky enough. Using a third party parts fiche as a service guide is, well,... not wise.

Yamaha's parts site (http://www.yamaha-motor.com/sport/parts/home.aspx) calls it a starter plunger. The service manual, on page 4-11, calls it a cold start plunger.

Regardless of what anyone wants to call it, the fact remains that it is only the "choke", and WILL NOT change you idle speed or anything else, no matter how many times you turn it in either direction, so what I said before remains in force; the idle speed adjuster is the bright metal screw at the float bowl joint, forward of the fuel line.

You just said that the TPS was never moved or adjusted. May I remind you that you opened with this?:

... i adjusted the tps sensor but no change.

So which is it?

Get a manual. Adjust your idle:

http://www.yamaha-motor-europe.com/community/service/manuals.jsp

[camlope24]

no... under the carb diagram its part #65

[camlope24]

i was mistaken about the "tps sensor itself" was not removed or adjusted. there is a black knob thats adjacent to it which i adjusted and was told this increases or decreases the ohms to the cdi. i was probably given mistaken information on this or misunderstood. the knob turns 4 or 5 full revolutions to the right and left side if sitting on the atv. its not the l/l choke thats on the left side of atv.

To tell the story i was riding no problems at all. stopped for a few minutes and wouldnt restart. sat overnight, checked basic..had full gas. started up cold but wouldnt hold idle keeps dying, hot, cold, warm...driving, anytime. took to a local cycle mechanic and suggested the tps and thats where i got my information. i have adjusted the "knob" , unplugged the sensor no change in anything. harder to start than ususall since this whole problem happened though. if i hold the throttle a lil bit it"ll run but if its decelerating and pull in clutch it dies also, must dump clutch to get it running again. i back probed power into the sensor gettng full 5V. another wire is grd and about 1.5V out of the 3rd. coming out of the sensor i get half the voltage manual says i need. i will look over the proper yamaha manual and see if this helps and can narrow it down..thanks

[grayracer513]

Now we have another problem: You said:

i have a 06 yz 450.

Now you say:

the knob turns 4 or 5 full revolutions to the right and left side if sitting on the atv. its not the l/l choke thats on the left side of atv.

You have a quad? That is not a YZ450, it's a YFZ450, and it has a different idle speed setup and carb. Please take your question to the ATV forum, and remember that to get accurate information, you need to provide accurate information.

[camlope24]

it was not the tps. yes it was out of time but adjusted and running fine now. thanks to all who replied. guess the vibration "tapped" it loose or something

[Crazyzilla]

if it was out of time, you need to replace your tensioner and your chain. It ont stay in time, you got lucky it only jumped a tooth or 2, next time it might mean catastrophic engine failure.