Setting TPS? Numbers bounce around....

[V8killR4U]

What would cause my TPS numbers to bounce in and not lock in. Trying to set the TPS and the numbers will not lock in on the scanmaster. Numbers fluctuate from .42-.46 The TPS is tightened, what would cause the numbers to bounce around?

 

[toomanymodz]

Either the TPS is bad, or perhaps the throttle cable is binding slightly, and the engine vibration is enough to pull the throttle slightly at idle. Disconnect the throttle cable to rule it out.

 

[V8killR4U]

Either the TPS is bad, or perhaps the throttle cable is binding slightly, and the engine vibration is enough to pull the throttle slightly at idle. Disconnect the throttle cable to rule it out.

I tried a new tps and the same thing occurred. I'll try disconnecting the throttle cable. Any other thoughts?

 

[RmvBfrFlght]

I tried a new tps and the same thing occurred. I'll try disconnecting the throttle cable. Any other thoughts?

To be honest, I'm thinking that +- 20 mV is OK. This is rather close, and within an 1/2 percent. Can't get better then that.

The other thing is, is that the TPS is an electromechanical device. Really nothing more then a variable resistor. Minor vibrations and change in the throttle setting will change it ever so slightly.

The only concern other posters may have is if the TPS is dirty or a little worn. In this case it can drive the ECM a little nutty.

So, since you have a new one, see how it is,. Then go from there.

RemoveBeforeFlight

 

[DailyDrifter]

Just a thought, but heat will change resistance. Try setting it with the engine cold and see if that helps. I've seen them fluctuate like your describing, but they have stayed somewhat "stable" enough to not cause a problem. Also during KOEO there is current being drained from the battery, it could be enough to cause a problem when setting the sensor. Make sure the blower motor and radio are off. Check the connections and grounds too.