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For a little while now, I've been dealing with inconsistent power in my truck. I'll get in it one day and it'll run like a dream, throwing me back in my seat when I step on it, and then another day it'll run like a sled and I'll experience poor acceleration. Like one day I'll try to take off real quick and it feels like I'm barely gaining speed, but another day I'll take off with the same pressure applied to the gas pedal and I'll squeal my tires. I've been reading around and it seems like the TPS (throttle position sensor) may be to blame, but from what I'm reading, it should throw a code. The local auto parts store has these things listed at $96, so it's not really in my "just throw parts at it" budget. First, if this thing is starting to fail, would it be inconsistent like this or would I be experiencing the same thing all the time? And if it is indeed the TPS, should I expect it to throw a code, or is it possible that it wont? Is there really any way to know for sure before I throw $100 at it? I'm not feeling like this is a super urgent problem because the good days far outweigh the bad, but at the same time, I hate it when my truck isn't running in it's prime. Any help is appreciated!
 

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A poorly performing may NOT throw a code... depending on the year the ECM may see that it functions but not be able to discern how well.

The answer is to see the TPS function on a scan tool. Sometimes codes describing overly rich or overly lean may appear, so it's best to
simply watch the ouput voltage of the TPS itself (if possible).
 

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I have had a TPS fail with no light, but it put vehicle into limp mode.
 

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Here are the basics of how a TPS circuit works.

At idle, the circuit sees very little voltage - so
the ECM does not schedule much fuel.

If you floor the pedal, the circuit sees max
voltage and so schedules lots of fuel.

The problem comes from when pedal movement does
not cause a voltage change. It's basically a
varible resistor.

Failures can also be of the glitchy nature,
meaning there is no linear, smooth change of voltage.
 
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