How do I test for a bad TPS? searched but...

[tx_sub]

tried the search but gave up.

how do i test to see if my tps is functioning properly? i'm trying to chase down my rough idle problem and all help is greatly appreciated.

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[tx_sub]

no codes. egr moves without binding, and changes idle when depressed.

 

[K5MONSTERCHEV]

Backprobe the sensor at the signal wire. It should be .5V closed, and 4.5v open.

 

[tx_sub]

with the engine running? or off or ingnition in on position?

and could it be bad and not throw a code?

 

[dyeager535]

You can test it with engine off, key on.

It needs to be smooth too, the voltage should change as throttle position does.

 

[tx_sub]

thanks

but i still would like to know if it could be bad and NOT throw a code?

 

[dyeager535]

Yes, it can, since the ECM interprets TPS voltage as a percentage of throttle opening. The ECM can't tell that you aren't holding the pedal down (for instance) when it is seeing voltage that indicates WOT, if that makes any sense.

It can be outside of the base range of voltage and I don't believe you will see any codes. Again, it comes back to the fact that the ECM doesn't really know how far your foot is depressing the pedal, if at all.

 

[Triaged]

You need to get a cheep analog (not digital) volt meter. Hook it up to the TPS and measure the resistance as you open the throttle. The analog meter will pick up "blips" that you would miss with a digital meter. It needs to be smooth.