The throttle position sensor is that small black plastic part with a 3 wire plug that is connected to the drivers side of your throttle body. You'll need a digital volt meter to check it and a screwdriver to adjust it. The optimim setting is .99 by loosening the 2 screws you can pivot the sensor ever so slightly. The object is to NOT exceed .99 although it usually comes from the factory way over that like 1.3 or under at .891 once you get it as close to .99 as you can the better the idle and response. It makes a world of difference.


Tools needed:

8mm socket & ratchet (to adjust idle set screw)

Phillips screw driver (to loosen TPS screws)

Multimeter (to measure TPS voltage)

I had to drill the holes out to a larger diameter to get the proper adjustment



How to check your TPS voltage:

Turn key on, but don’t crank engine

Put positive lead of multimeter on grey w/ white stripe wire (middle wire)

Put negative lead of multimeter on grey w/ red stripe (bottom wire)
----you can also put it to your battery it is simply a ground

use the leads on the multimeter to back probe into the connector

You should get under .99 volts.. Anything over, and you'll need to adjust it.

Make sure you have your idle set where you want it by moving this set screw:

Tighten- increase idle

Loosen- decrease idle

Loosen the TPS screws slightly:

Turn the TPS clockwise to raise the voltage.

Turn the TPS counter clockwise to lower the voltage.

Move the TPS slightly, and check with the multimeter. When you get it to where you want it, tighten it back down.

My voltage was 1.28 before, and .989 after.

I picked up this how to and a different website and figured i would share it

 

Yea, -I had to drill mine out to get to 99. I was like 103 Factory. I used Coil bolts (7mm) instead of the TPS Philips heads as well. -

 

Either one of you may not want to believe the following!
Each time the ignition is turned on, the program resets the "starting point" in the TPS position table.
This action automaticlly adjusts for changes in the TPS resistance over time, temperature and wear.
As you know, this sensor gets the most use from movement of any in the system.
Yet their replacement is relitively infrequent over the average life of the motor.
This auto set function has been in use since 1985 in all the FI motors and accross all the computer generations.
Bottom line, it makes little difference what the voltage is due to the way the PCM handles it each time the motor is started.
If the voltage goes too high or to low, there is a code set to alert to that type fault. Seldom do we see those codes due to the quality of the sensor and it's design.
This setting of the TPS is an old trick item and has not been noticed that the PCM will only change it's operating point after some relearning time, so does not really accomplish anything permant.
Bottom line is you cannot take control away from the PCM, in reality, by making an external change of this type, no more than you can really change the idle speed unless you set the stop screw up, that is an illegal action unto it'self and causes other malfunction, if done.
Setting the voltage may, on a temporary basis, seem to richen the fuel but will not stay at that level after the PCM returns the zero set and pulls the fuel back again.

 

Back when I did this, it was my impression Ford Motor was in error, so I did the deed like everyone else was on this site , -way back when. I also choked up the accelerator cable behind the fuel pedal. Needless to say, it never amounted to anything... Unless you forced yourself to think it did.

 

what exactly does this do? better throttle response?

 

you got it raptor

 

Vintage stuff.....
https://www.f150online.com/forums/li...ttle-body.html

 

hm. might have to check this out tomorrow

 

The 'how to set reference' is loaded with miss information about what the TPS does.
1 It does not set curb idle.
...a, the curb idle is program table defined with a +/- of about 50 rpm.
...b, the idle speed is controlled by the IAC that is varied by the PCM until the crank position sensor tells the PCM a match with the table is found and settles in at that point with very small corrections ongoing.
2, The TPS does a lot if things such that you cannot make a perment setting have any effect after the PCM does a correction for it's altered setting.
...a, the TPS provide the PCM with a sense of throttle opening and to make fuel and ignition timing adjustments along with inputs from other sensors.
...b, It detects the 'rate' of throttle movement that adds more fuel for accelleration (same function as a pump on a carburator).
...c, It's relitive position is used to help tell the PCM when to call for gear changes.
...d, It's relitive position is used to tell the PCM when to call for EGR and when to release it.
...e, It is used to tell the PCM when the motor is in decelleration which does a number of things such as cut fuel, close the IAC just enough to keep the, motor from stalling, release the converter lockup for sudden braking application and more.
..f, The TPS tells the PCM when about 7/8 throttle has been reached to go to rich fuel tables and not use the OX sensor inputs. (bad for fuel mileage).
..g, setting idle stop position other than factory spec upsets the IAC control such that cold start, hot idle, A/C loading etc all may be affected.

There is more but this is enough to see that trying to fool the PCM by adjusting the TPS voltage has little effect after several restarts, the PCM makes a table correction for.
The PCM will not allow any permant change to this sensor setting to alter what the program does as discribed above. There is to much going on and at stake to allow it to happen.
Most who try to say it's a mod for performance do not know much about what is involved.

But, have fun trying.

 

Hey Bluegrass thanks for the info..I have my voltmeter out and I went out here to see what setting to use it on to make the adjustment, I didn't know it would just reset a number of restarts afterward, so back to my tool box the voltmeter goes lol. I also tried that "gotts mod", I wasn't impressed with it. I'm not saying anything bad about gotts2bme, just saying I'd rather put on a real cold air intake and know I can't do much better for air flow than to just remove a snorkel and still have two other restrictions in the air track..right where the snorkel goes into the filter box because the end of the filter is too close, and also the silencer tube in the elbow. Thanks again for saving me the time on the "tps mod".

 

That's a misnomer. It should be called a "warm air intake". The air under the hood is a lot warmer than the air in the fenderwell.

 

Lol I knew someone would comment on that, it didn't take long either. That's ok with me because the volume of warm air is much greater than the small amount of cold air from the factory box, I see it as a good compromise and the added sound should be kind of fun.

 

Just to review, these ideas of free power by simple changes trying to defeat the computer program won't result in any permant results.
The only areas you may see some improvment is with exhaust and wide open intake air, but only at higher RPM where restriction begins to be a factor with the stock systems. Otherwise the stock system is tuned more than most realize to get the motor to pull it's best, for truck use.
A small improvment in the ability to intake air again at high RPM may be of benifit but again it's at high RPM where a truck in not normally run at on the average.
Last, if the program is altered to take advantage of certain parameter changes, then a reasonable improvment can be felt but this is a change in program you can't make from just making outside mods.
Many try to debate the points but you cannot alter program control from the outside without some un-intended consequences.
The program is composed of many software tables that make the logic decisions.
If a mod causes any table to shift out of it's normal design tolerence, a code is set and no gains are realized.
Good luck.

 

Just wanted to put this out here for everyone. What Bluegrass said is 100% correct, the computer calibrates the TPS resistance every time you start the engine, you can watch this on a good scanner or even free ForScan. I have a 99 F150 that likes to unlock the converter clutch at very light throttle because very light throttle because the PCM considers very light throttle as closed throttle and closed throttle unlocks the converter clutch at lower speeds. So for example the TPS voltage reading from .99 to .1.02 is closed throttle, then 1.03 and up is part throttle. I added a 170ohm resistor to the TPS circuit to drop the voltage by .03. Now I start the truck with the TPS at .96 as the baseline for the PCM, and then hit a bypass switch eliminating the resistor and bringing the reading to .99. Now .99 is the very top of CT reading and 1.0 is PT.

You don't want the PCM to read PT at idle because it will kick the idle up a bit and it's just not pleasant for driving.

The converter doesn't unlock at light throttle anymore, it also locks just a bit later when accelerating, off idle throttle response is crisper. I could probably stop being cheap and buy a tune for the truck but this was just too easy and worked great. I highly recommend getting ForScan, it's a huge help for almost no cost.

170ohm was calculated using a potentiometer/rheostat basically an adjustable resistor, like a dimmer switch. I could watch the adjustments to the TPS in real time on ForScan, total cost was about $15.

 

Hello again.
Something else that goes on with the sudden closing of the throttle while driving is it does unlock the converter by intent so the drive train becomes 'soft' in case Emg Braking has to be done, the lockup does not contribute to a longer Braking distance.
If the Brake is not pushed, Trans Lockup is reconnected again within just a few seconds.
At speed about 55 mph, watch the Tach action to see this work.
Under light Quick off the throttle and back on should show the Tach increase about 300 rpm then fall back to the locked state as a test. Don't touch the Brakes.
Good luck.