Throttle Position Sensor - Explained

How does a throttle position sensor work? What is a throttle position sensor? What systems utilize a throttle position sensor? This video explains a throttle position sensor.
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[@8180634]

Your description for what a TPS does is good, but your description of HOW it does it is not entirely accurate. It works more like a voltage divider. Most TPS are 3-wire; power, ground and feedback. The resistive element is connected to Vcc on one side (typically +5V) and ground on the other. The voltage along the resistive element will drop as you approach the ground side. So the voltage read at the wiper will drop as it approaches the ground side. The ECU reads the voltage at the wiper by reading the feedback line. Google throttle position sensor schematic and the pictures will explain it better than I did. I hope this is helpful. :)

[@MetalMasterdom]

4-wire. If you know what the "idle" signal is for. A little less google...a bit more get under the hood and see(and/or read a proper service manual) next time ;)

[@stopthephilosophicalzombie9017]

@@MetalMasterdom They are actually typically 3 wire.

[@baguett123]

I just want to say thank you, you are doing an extraordinary job in your videos. I dont understand everything, but with the drawings etc. it is easier to understand and i appreciate that. Keep on the good work!

[@EngineeringExplained]

You're very welcome, thanks for watching!

[@srshwa]

Bro this video is 8 years old and it helped me out wonderfully. lol I just saw your Channel is massive now. Awesome job.

[@rayjoyce1]

Good video no music and no bullshit

[@EngineeringExplained]

Ray Blouin Thanks! Try to keep most of my videos no music no bs.

[@EngineeringExplained]

Glad to hear it, you are very welcome!

[@EngineeringExplained]

I believe so, I think it could be done either way depending on how you set it up.

[@EngineeringExplained]

Great question, I don't know. But perhaps I can get to making a video on it eventually!

[@EngineeringExplained]

Those, and in addition there could be a map sensor, iat sensor (intake air temp), as well as O2 sensors.

[@EngineeringExplained]

The TPS will be used in conjunction with other sensors so that air density is known. It won't be the only factor in determining A/F ratio.

[@EngineeringExplained]

Thanks! You may post your suggestion on my "Suggestions" page on my website. The link is in the description, thanks!

[@charlesmills6169]

I have a question.i have a mustang that has m.a.f.the car is modified and has no o2 sensors.the car pretty much runs great,but sometimes when im in second gear at low rpm.and put the throttle to the floor it has a flat spot.it seems to only happen in second.under a load.do you think I have a bad tps or is it because it doesn't have o2s to give the ecu more imformation..any tips would greatly be appreciated.like I said its when im in second gear,at low rpm,and im trying to spin the tires.

[@HappyInHerLife]

So glad I founded your channel!!!! Great work!!!! I'm really astonished!!!!

[@EngineeringExplained]

You are correct.

[@EngineeringExplained]

Thanks!

[@EngineeringExplained]

I have videos on disc and drum brakes, braking distance, and will have one soon up on vacuum assist. Search for my "brakes" playlist on my channel page. Also, the drilled holes are for additional cooling for the brakes.

[@jeffreyhickam1459]

My 02 eclipse gt 3.0 is having problems idle'ing right after starting? It's been necessary lately to give a lil gas to stay going which I never had to do before? I replaced the Idle control valve, & removed my cold air intake but still I have the problem. Please HELP!! Thanks & love your content!

[@anthonysmith5979]

A very simplistic view of what is not shown but when they were first introduced you're somewhat on the mark. many improvements and additions since.

[@lanevoFQ]

So am i correct in assuming that when the tps opens up, there is more resistance being added there by lowering the voltage sent to the ECU? I'm just wondering whether the ECU reads more voltage as an open throttle or reads less voltage as an open throttle.

[@musabfeltman1311]

Thanks for rhe clear explanation Jason great job. Keep it up.

[@averagejoe6150]

Ok. This situation has me stumped for a solution, and others I know as well. My good friend, Kevin, has a 94 z71 Silverado. he currently has a 305 tbi with a 4l60e transmission. He's wanting to do a swap to a 454 carbuerated. But, since the 4l60e runs with a tbi and needs a TPS to be able to function properly, it won't work with a carbuerated engine. Now, this is a budget build so buying another transmission is a last resort. Is there a way to fool the transmission into thinking that we do have a TPS on the intake and force it into proper function or is another transmission really the only way?

[@tribalblood]

I really liked your videos and it got me more informed about the mechanics involved. However i have a question, I have a 150cc yamaha motorcycle (szr 150) that has a mikuni BS26 carburator, it is not a fuel injected system nor has any ECU unit, its butterfly valves are purely controlled by the twist of the throttle and i can not visible see any mechanics involved that connect the engine or carb to any automated system but it still has a TPS sensor. What is the need of placing it there??

[@EngineeringExplained]

Unfortunately I really don't know. But I would definitely get some O2 sensors. They're not pointless by any means, should have a video up about them within the next couple weeks.

[@EngineeringExplained]

Well I think my channel is more in line with education. For car reviews I think the powerhouses are SaabKyle04 and Motor Trend, both of which do a great job.

[@ThisIsNotSharyn]

Very genius way of making a sensor. Thanks for the vid.

[@jaiandood]

Does this affect the timing of the timing belt? Me and my friend took the tps out and put it back incorrectly. A mechanic told that this will change the timing? If so, if i put it back correctly will the timing normal again?

[@rajadeepakkumar27]

Awesome explanation!

[@EngineeringExplained]

Well, for example, many cars run rich at wide open throttle, and this is done so that the cylinders don't get too hot. By using the TPS, your ECU will know to inject more fuel than the MAF is saying to inject, because the MAF is trying to achieve a specific A/F ratio that the TPS is telling the injectors to exceed.

[@skmkenya]

I have a 01 sentra 1.8l and its acting weird...when i try to rave the engine it sounds lik it has a misfire but when i didconnect the wires going to the TPS is raves fine without chocking.what do you think could be the problem?

[@MetalMasterdom]

Modern electronic automatic transmissions also need TPS input(for torque convertor lock-up). For that the ECU/ECM/PCM needs to know when the throttle is fully closed or not. There's an entire circuit in the TPS dedicated to that alone(a.k.a. the "idle" signal).

[@cdsalwathura]

hi friend. i would like to know the acceleration sensor.how it works

[@boostedred_473]

Can u do a video on 4 wire tps vs 3 wire tps sensors

[@freshprodoose]

my chevy van is bogging out of first its like a gradual build up of speed versus last week when i laid into it she SKIRTED OUT OF FIRST QUIIICK now not so much i have a 4.3 vortec could this be the case in my situation?

[@noobiegameplay691]

Is it possible that the TPS reading is 0 during engine idle or before engine starts?

[@salazarvic2]

Hello, I watched your video on the TPS but you did not explain how to test it. Can you please explain how to test the TPS and explain what symptoms you may get with a bad TPS? This would be something good to explain on all of your videos when explaining what a specific part does. Thank you for your videos

[@c4car478]

AWESOME EXPLANATION THANK YOU SO MUCH.

[@xai1603]

I would like you to do another video on tps as to what happens the injectors as it reads for higher voltage vs lower and what happens to these components when you set the tps too high or too low. that would be great.

[@jancoscholtz]

Nice explaining thou I appreciate it.

[@BrokenCrownRecords]

i kwon the funtion of many artifacts that deal with a variable resistance to tell the ecu a little info, but the question that i have is if the plate mass airflow sensor could be repalce with a TPS Sensor to eliminate that obstruction it makes on the intake tube of my engine. it seems to be heavy and it may causing a the engine not to breathe well. since both are different and do the same job what can i do to get rid of the plate mass air flow obstuction????

[@nitinkamble1725]

Can u please show how the ECU controls the fuel injection in engine by sensing the position of accelerator paddle and input and output to ECU in this (like in throttle position sensor ECU uses voltage difference to sense the position of throttle )

[@bradleyglen6283]

Can you assist my question:The TPS reading plays a vital role in the mapping and map switching . Therefore it stands tor eason while I am trying to gain economy , with my TPS incorrectly seated , the maps are being switched in earlier or later than they should . My assumption would be that the TPS voltage has to be set and recorded before any tune OR by factory to align the maps being used correctly . Alternately the TPS can be used to fine tune the AFR based on its position at a certain RPM.Thanks in advance-Well done for appearing on Between the Lines Documentary -awesome Subaru magic

[@freestylemike3445]

I have a 70 millimeter throttle body we set it at 5 we open the throttle reeds 4.5 I didn't have that tps on for a week and my check engine light is on do I have a bad TPS sensor or did I do something wrong by trying to set it at 5 where it supposed to be at

[@ClarkBark14]

KZbin recommended after watching your more recent videos, just wanted to comment on that mop on yo head! Would have been bad in your new MX5! :P Keep up the great content!

[@drewjennings-grisham7778]

Is the TPS calibrated for a specific engine size and will that affect the engine performance if I put on the wrong one? I'm asking because I have a 3.0L V6 but when I look for a replacement part, they all say they are for the 3.5L engine model. Will that still be compatible?

[@tribalblood]

Come to think of it i have seen many carbs that have a TPS but are not fuel injected such as mine and only use the jet needle assembly to inject fuel mechanically. Whats the use of TPS in this case ?

[@habiks]

So what if potenciometer gets bad (dust, etc) - can it be a scenario for out of control car? (or do all cars have mechanical linkage to carb and throtle position is just info for ecu?)

[@EngineeringExplained]

You're welcome!

[@prandomable]

so there's TPS and Mass airflow sensor and what else in a vehicle to determine how much amount of fuel's needed to be injected?

[@PhattyMo]

For those of you who understand electronics: It's basically a potentiometer tied to the butterfly shaft. One terminal connected to the 5V reference voltage,the other one is grounded,and the wiper goes to the ECU/PCM/whatever. :)

[@KongLee_21]

Could u do a video about ITBs and compare to a regular throttle bodies pls?

[@1983bigfrank]

Just subscribed explain simple and beautiful

[@aadamsafi3551]

Can I ask what the Position Sensor Controls? The butterfly valve that the TPS is linked to controls air flow through the engine, but at the end you said that the ECU controls the amount of fuel to provide. Could you explain the step by step please?

[@bobbyd9583]

The throttle position sensor is just part of an array of sensors used to determine the amount of fuel to deliver. For an example we will pair the throttle position sensor with the manifold pressure sensor. (speed density system) Scenario: you snap the throttle to 20% and hold it. What's happening: 1.) The throttle position sensor detects throttle movement and tells the ECU that you are depressing the accelerator. 2.) The manifold pressure sensor spike up in response to the now opened throttle valve. 3.) The ECU reacts by measuring the difference in vacuum from the last 15 samples then compares the return value to the current throttle position. This determines the engine demand. 4.) as the vacuum returns to the intake the manifold pressure sensor detects the change and the ECU can see it. 5.) The ECU shortens the pulse width to decrease the volume of fuel being delivered as engine demand is now lower. Obviously I skipped some other things that happen in the system in the real world as this was only an example of the two most common sensors next to the throttle body. There is obviously more to the equation, such as fuel trims, oxygen sensors, crankshaft position sensors, ignition timing. Also there are Mass Airflow style systems which react in a similar fashion to speed density systems but have the added advantage of actually calculating the air volume coming into the engine to establish a more accurate air fuel ratio.

[@EngineeringExplained]

How would I go about this? I ask because I have no idea.

[@TK-ok6hk]

I think that when butterfly valve is in 180° position (it lays and air has the easiest way to go further) the resistance is at minimum. So if you declare ohm's law U = R*I, where U is voltage, R is resistance and I is current, you can find out that there is the lowest level of voltage when you floor the pedal (opened air breathing) and when pedal is not touched (butterfly valve closed the air income) the voltage is at its maximum. And you know it.. sorry for my ENG, i hope you can read it :-D

[@darriant5754]

this has helped me with a presentation, thanks

[@sulemanmito4578]

Nice explanation

[@0bigantney0]

Does the rate of air intake depend on a vacuum in the cylinder or is there a turbine in accordance to the throttle that sucks in more air?

[@EngineeringExplained]

Good call, I don't see a reason for having TPS interfere with ABS; obviously you would want throttle at a minimum if you're trying to slow down.

[@erickochoa3288]

Dude, thank you. I'm putting a corvette tb on my mustang ($200 cheaper) and was worried about the voltage not being the same. Thanks again. I owe you a few beers lol

[@vaibhavdesai8288]

what will happen if i unplug TPS? or if i replace my throttle body with smaller or bigger size throttle?

[@EngineeringExplained]

Follow the cable? If it connects to nothing, it may not be a TPS.

[@anthonystompanato3852]

Nicely explain junior

[@dmroberts899]

In your other video you mention the mass airflow sensor is also responsible for fuel injector flow; can you elaborate why both the TPS and MAF are needed for injector flow? What does one do that the other cannot with regards to the injectors?

[@adwnasa1]

is TPS with Carburetors same as EFI ?

[@iwin4985]

great video. thank you for showing a real one.

[@zvonimirbobicex-4962]

is that the same as the throttle switch?

[@jimbuddha]

It seems to me that the TPS is another sensor that tells how much air flow is coming in so the ecu knows to inject more or less fuel. But then why would you need a TPS AND a MAPS?

[@jordanjoestar8839]

Stephen Pentony map sensor is allot more precise. Think of it as a team. One is the muscles the other is the brains. One gets a base parameter, the other fine tunes it. Thousands of times per minute.

[@samsen201]

Can TPS have any impact on Tranny or how Transmission handles? I am hearing it can be the cause for RPM going way high and car not shifting to higher gear. A reason that someone may suggest you to rebuild the transmission!! Is this true?

[@joescheller6680]

yes it happened on my 3.3 nissan engine and the transmission wasnt shifting when it should to a higher gear resulting in over reving RPM before shifting up

[@vqfive]

What was that other black connection on the top of the throttle body.

[@chumanilakota]

I'm so late with this but thank you for your help. I found a family auto shop that works on VWs and Toyotas only. I didn't screw it up at all. It just needed to be updated in the computer.

[@akashnaidu2873]

hey are MAPand TPS sensors same??

[@EngineeringExplained]

Take a picture of it (and if you have pictures from before, that's helpful too) and post it on a VW forum. I guarantee people will know where to get you going from there. has everything been reconnected properly? I guess that's an obvious question.

[@csipes1983]

What could be the problem if my scan tool reads absolute throttle position erratic? Even when the vehicle is engine off key on. If I do not press on the peddle the reading erratically goes from 0% to 10% or so, back and forth. It does this while idling too. I checked for 5v reference and 1 to 5v output (as peddle is pressed). Seems good data is coming into pcu, it’s just interpreting wrong.

[@prandomable]

this sensor tells the ECU how much fuel to be injected. If it fails then the fuel injecting rate will be consistent and same?

[@EngineeringExplained]

haha good to hear!

[@aldo7962]

Can you damage an engine running a bad tps?

[@brandonpenrod7433]

I am almost upset about this young gun knowing so much more than me, and well enough to explain it in simplistic terms. But what the heck, good job kid, keep it up.

[@user-cb1vo1ik4b]

thankyou... from your description of what a TPSensor is and how it operates, it's just an overpriced volume pot or a rheostat...analog to boot...no to reboot, lol... constantly as I am doing this very minute...informative platform here, pleased I found...

[@zohraqainnaqvi2308]

Good advice

[@ab030mar]

Did U think this sensor (if its defective) will cause difficulty shifting in auto transmission ???

[@eduardodaquiljr1621]

Voltage divider circuit is fixed to a certain resistor division of a circuit,whereas TPS sensor works on rheosatat or variable resistor circuit such as volume control,etc.

[@EngineeringExplained]

Hmm not sure about your idling problem. My car will idle at about 1500 on a cold start, but as soon as it's warmed up it goes down to about 800. Never bounces at a stoplight or anything like that unless the A/C is on, which of course when the compressor turns on the engine rpm takes a small dip, then rises back.

[@Jetset_kev]

Keep it up man

[@EngineeringExplained]

Seems like that would be a possibility yes.

[@melellington4892]

Good explanation but useless for me. I need to know if the TPS is the cause of my crank/no start condition. My 1995 Honda Civic (1.5L) runs perfect once I get it started but will not start without spraying starter fluid into the throttle body. It will also start IMMEDIATELY when I jump a spark plug wire to ground to verify there is sufficient spark. I have tested and replaced all the usual suspects, except the TPS, MAP, fuel pressure regulator and injectors. There is plenty of fuel pressure and the injectors pulse well. I'd like to know if a bad TPS can cause a crank/no start?

[@tacticalsniper2012]

Just curious , could you drive with this sensor inplugged? Would you see any performance change?

[@tacticalsniper2012]

Unplugged*

[@Taikausko]

My car stalls right away when TPS is disconnected

[@abdullahumer1683]

How does the TPS effect an automatic transmission shifting? And is it the same in both manual and automatic transmission cars?

[@EngineeringExplained]

Yes, it's pretty much the same regardless, but in an auto it can use the position of the TPS to determine what gear you should be in. If you stomp the pedal it'll downshift because the majority of the time putting your foot down indicates you'd like to accelerate quickly.

[@VibnWavez]

Engineering Explained I have a 1999 Sentra Se Auto (with an Infiniti G20 engine, but it's the same as the Sentra Se's 2.0). It throws a code for TPS, and it will not downshift when I press the throttle hard. Even floored. Do you think the TPS is the problem? It seems to be. It also has a MAP sensor code/vaccum problem, and one for the MAF, but it has a cracked intake hose and a missing vacuum line at the top of the intake hose, so that's the problem causing that code. Occasional stalling and bucking occur too. I'm thinking the MAF for that one though.

[@Drifting50]

So would it be safe to say that the majority of air flow systems in an engine are regulated by the ECU measuring current, voltage, or resistance and then changing fuel injection appropriately?

[@EngineeringExplained]

Yep.

[@wolfpack4128]

The on/off strategy is called Pulse Width Modulation (PWM). It is how most valves are commanded and how many newer sensors read their inputs.

[@EngineeringExplained]

Depends on the cylinder vacuum.

[@aliqadri4672]

What does tp sensor do with maf sensor.??

[@SuperDiscopotato]

Hey dude you're genius. Reckon you can post a vid about engine stroking? That'd be great!

[@dongjunkim4741]

what happen if rheostat is used instead of potentiometer? what's gonna be different?

[@Shakingcow141]

You should try and get your hands on a press car so that you can do a car review i would really enjoy hearing what you had to say about different cars. Maybe the scion FR-S or maybe BRZ? Just a thought

[@imantisocial3179]

also, have you checked your spark plugs?

[@warpath2k]

the rpm meter is connected to the distributor (or modern equivalent) and monitors how fast the engine is receiving ignition and transfers that signal to the rev counter

[@ljsablad]

does a correct tps voltage affects the fuel consumption of a car? just asking

[@scottykilmer3920]

yess it does affect the fuel consumption. Over time this sensor wears out, and will not read the same voltage anymore. It makes the fuel trims rich if the voltage is higher, or lean when its reading lower voltage. It also makes a big difference in acceleration and torque feeling !

[@mohammedcherifi9206]

On most of the throttle bodies i find tps1 and tps2 but where the second one is located??

[@chesshooligan1282]

I have a 2004 Suzuki GS500 that has a throttle position sensor. However, the bike has no traction control, no electronic fuel injection (it has a carb), no ABS, and no cruise control. What, then, is the TPS there for?

[@ahmadnazri2991]

tps also for efffect automatic transmission shift

[@mattdloughy5369]

What was the sensor on top of the throttle body?