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what does a throttle position sensor do?

A

andylawcc

Lifer
EDIT:
so I went to Toyota dealer and bought a TPS. went to my mechanic today and he said my original TPS is fine. so I went back to the dealer and they say they do not accept returns on Electrical Component (it is actually written in 36-sized font on the invoice.) I got ownzedddd....




this is the definition I found on line...

First a little lesson on what the TPS(throttle position sensor)does for your engine. The TPS(Throttle Position Sensor) monitors the throttle valve position (which determines how much air goes into the engine) so the ECU can respond quickly to changes, increasing or decreasing the fuel rate as necessary. The TPS is really just a potentiometer or a variable resistor not much different than the volume knob on your radio. The voltage to the ECU from the TPS changes in proportion to how far into the gas pedal you are.
Click to expand...

recently i am experiencing a 10-15% drop in fuel economy when the engine light is on; and when its off, gas mileage go back to normal (roughly). I checked the ECU with an OBDII reader, and it reports the engine light is due to failed/shorted Throttle Position Sensor. The light been on and off for quite some time.

Now, my question is,
1) does fuel economy has anything to do with the TPS?
2) other than lowered fuel economy and reduced horsepower, do you recommend changing the TPS? It costs 95 bucks from Toyota dealer. A Mechanic recommends the OEM one coz afteramarket ones just don't work right.

my car = 1996 Celica. 7AFE.
 
You answered your own question....
1) does fuel economy has anything to do with the TPS?
Click to expand...

recently i am experiencing a 10-15% drop in fuel economy when the engine light is on;
Click to expand...

I checked the ECU with an OBDII reader, and it reports the engine light is due to failed/shorted Throttle Position Sensor.
Click to expand...
 
If your TPS is reporting incorrect info the ECU, yes you could be using too much fuel. If the throttle is opened 10%, but is reporting that it's opened 40%, the ECU will be supplying more fuel than is needed. Other sensors are involved in fuel delivery algorithms, but you essentially get the picture.

You have the potential for more frequent replacements of O2 sensors, clogged catalytic convertor, coked up throttle body, carbon buidup on intake valves (potentially expensive repair), fouled sensors in the intake stream, etc. Oil changes will need to me more frequent due to raw fuel getting into the oil. Plus, if your area has emissions testing, your chances of passing are greatly reduced.

Change the TPS and listen to the mechanic. Use the OE part. He probably has the experience to back up his statement.

Edit: I should add that with fuel prices as they are, this repair will pay for itself quickly. You should be able to do this swap yourself with basic tools.
 
Originally posted by: Eli
You answered your own question....
1) does fuel economy has anything to do with the TPS?
Click to expand...

recently i am experiencing a 10-15% drop in fuel economy when the engine light is on;
Click to expand...
Click to expand...

but there could be millions of other factors... and I don't want to blame the TPS solely. Corelation and Causation are two different things; just because two incidents occured at the same time doesn't necessarily mean both HAVE to happen at the same time. i just want to be sure.
 
Originally posted by: boomerang

You have the potential for more frequent replacements of O2 sensors, clogged catalytic convertor, coked up throttle body, fouled sensors in the intake stream, etc. Oil changes will need to me more frequent due to raw fuel getting into the oil. Plus, if your area has emissions testing, your chances of passing are greatly reduced.
Click to expand...

yikes!! okay, I am convinced.

this repair will pay for itself quickly. You should be able to do this swap yourself with basic tools.
Click to expand...

okay, thanks. I know where it is, I just hope I have enough strength to pull the two screws/bolts out.
 
Originally posted by: andylawcc
Originally posted by: Eli
You answered your own question....
1) does fuel economy has anything to do with the TPS?
Click to expand...

recently i am experiencing a 10-15% drop in fuel economy when the engine light is on;
Click to expand...
Click to expand...

but there could be millions of other factors... and I don't want to blame the TPS solely. Corelation and Causation are two different things; just because two incidents occured at the same time doesn't necessarily mean both HAVE to happen at the same time. i just want to be sure.
Click to expand...
I understand, but if the ECU is reporting a faulty TPS sensor, then you need to fix it.

Don't let your engine run out of tune like that, fix problems as they arise. Even if the TPS wasn't 100% the cause, it still needs to be addressed.
 
hit the junkyards. Toyota probably uses the same TPS sensor on lots of their engines. You just need to figure out which ones are the same as yours.
 
Originally posted by: thedarkwolf
hit the junkyards. Toyota probably uses the same TPS sensor on lots of their engines. You just need to figure out which ones are the same as yours.
Click to expand...

problem is, you don't know what kind of condition it's in...if it's an intake manifold or something it's pretty easy to see if it's good, not so with something electronic like that...personally, when it comes to sensors and the like i always buy new, that's just me though

 
Originally posted by: quakefiend420
Originally posted by: thedarkwolf
hit the junkyards. Toyota probably uses the same TPS sensor on lots of their engines. You just need to figure out which ones are the same as yours.
Click to expand...

problem is, you don't know what kind of condition it's in...if it's an intake manifold or something it's pretty easy to see if it's good, not so with something electronic like that...personally, when it comes to sensors and the like i always buy new, that's just me though
Click to expand...

Thats true but you can bring a mulitmeter with you to test it. Plus I haven't paid more then $5 for a junkyard sensor yet. If it doesn't work no big deal.
 
Just get a new one, they're only like $25 to $30...

I replaced mine in my Blazer and it made a hell of a difference...
 
Yea when they did mine on my pos Taurus it made a real big difference. Just one thing the TPS cannont tell how much air goes into the engine, that's what the MAP sensor or the other kind of sensor I forgot the name of is for.
 
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