TPS Again!

[Guest RobB]

I know this has been hashed out endlessly, but what are the signs of a

defective TPS unit? I'm starting to wonder if mine is blinking out; it is

incredibly sensitive to throttle adjustments from a "neutral" throttle

position, especially at lower speeds, and particularly at/around 4K.

At 4K, the bike will surge and buck unless I have the most delicate

of hand pressure. I have synched the throttle bodies, and the dealer

just checked the TPS value; it was slightly off, but not too bad.

It does change quite a bit, as I've had to adjust it 4 times in the last

7K miles.

 

I don't think this is simply a matter of going to a Power Commander,

but thought I would follow the TPS unit lead first.

 

Thanks to all!

 

Rob

[Mike Stewart]

The best way to check a TPS is with a scope. I happen to have a hand held fluke unit but most shops will not have one. This bugger cost me over $3000. a few years ago. You need to check the scope pattern to see if there are any spikes or glitches from closed throttle to wide open throttle. I have checked mine and Al's and both were good. Is your bike totally stock? It sounds like you are running lean in the rpms that you are having problems with. What year bike do you have?

 

Mike

[Murray]

You can pick up an older lab sized scope for around $250 US athough with the older equipment its no as easy to use and you kinda need to know you way around them. The other cheaper athough not as accurate thing to do is to hook up two mutimeters in resitance mode one to each TPS. Sit them side buy side and watch them as you gently open the throttle from zero to full. If the reading starts to jump around a bit on one you know its on its way no help of course when they are both a bit crappy at the same piont but highly unlikely in reality. The TPS does have a twin ramp setup so there will be a change in the amoung of resitance change per turn on the throttle. Someone did go tot he trouble of working out all the facts and figures maybe try the Guzzi Tech site off the American or Australian board.

[Cliff]

Another alternative

Disconnect the TPS and connect an ohmmeter to its terminals. Its just a potentiometer. Two terminals will show no change in resistance but the other combinations will. You should see the resistance change with throttle in a linear sort of way.

 

Another way - connect a 1.5V battery across the TPS and a speaker via a capacitor. Listen for that gravelly old transistor radio sound.

[Janusz]

I am shooting in a dark here but when playing with my Power Commander there is an advanced function of setting your throttle from 0 to 100%. I did it once some time before and being generally a computer semiliterate does not help either, but you can observe on you laptop screen how the throttle smoothly (or not smoothly perhaps) changes.

 

Would that be useful to asses your TPS in a sense?

[dlaing]

I am shooting in a dark here but when playing with my Power Commander there is an advanced function of setting your throttle from 0 to 100%. I did it once some time before and being generally a computer semiliterate does not help either, but you can observe on you laptop screen how the throttle smoothly (or not smoothly perhaps) changes.

 

Would that be useful to asses your TPS in a sense?

That is what I was going to suggest! Or get the MDS diagnostic software for our ECU.

Probably not as accurate as a scope....