The dreaded throttle position sensor

[and0r]

Alright,
first noticed my 99 EB with 2WD was struggling to climb hills, the engine would increase RPM, but the power output just seemed flat. This would also happen on leveled surfaces too sometimes, depending on how I launch the vehicle from a standstill. This all really felt like a failing torque converter, like the impeller or stater fins were running flat or broken loose. It really felt like the power was being totally lost at the transmission, but not in the direct gearing, or any of the drive clutches, just at the torque converter. Then, after some basic google research, I was informed of the throttle position sensor, which made a lot more sense to me.
As some of you can already see where this is going, I managed to strip the bottom screw which holds the sensor in place. This is a very common issue with many ford vehicles. I can't imagine why none of this turned up in everything I researched about replacing the TPS. Absolutely no warnings about these screws which are practically welded on the throttle-body. The official service manual does not even give proper procedure in removing this. You absolutely must remove the assembly which holds some kind of EGR valve or EVAP doo-hickey and there is some other related tubing connected to those things, and the official service manual mentions nothing of this. None of the Youtube videos warn of the stuck screws either. Very frustrating!

Anyway, I would like to know more about this component. There is simply not enough information here regarding all aspects of it.
How does this component fail? There seems to be no moving parts, and judging by looks alone, it seems to use magnetism to detect the position of the TB.
Also - mounting. Does the surface need to be clean? I hardly loosened the top screw, maybe a half turn, and I am getting bursts of high idle and fault code/CEL for the TPS, also the transmission doesn't know when to shift gears anymore! I am certain the PCM uses the TPS signal to also control the transmission!
This component seems very delicate, so mounting it must have special procedure of some sort. Some kind of additional info here would be much appreciated.
I am also considering the connector for the TPS too, my chinese multimeter broke a probe, so I cannot even test the TPS or its connection.

 

[and0r]

I am also going to just remove the entire throttle body and see what I can do about this stripped screw now.
I'm thinking of using a bolt extractor bit, and if that fails, then cutting the head of the screw off with a dremmel, removing the sensor, then using penetrating spray and vise-grips to unscrew it.

Where can I find replacement screws?

 

[and0r]

I see that it just needs to be mounted tightly and evenly, and with fresh locktite. But more precise info here would be helpful. I think the TPS also needs to be recalibrated.

I had the battery disconnected for several hours.

Makuloco shows how to recalibrate here in this video.

 

[and0r]

Ok you need to heat the TPS mounts to loosen the locktite. Makes sense.

 

[Dewayne]

Tps sensor is a potentiometer and works like the volume control on your radio. 1 wire will be ground 1 wire is 5 volt 1 wire is signal to computer, when you remove it you will see how it is moved by the throttle body. At closed throttle you will have low voltage coming out of signal wire at WOT you will have near 5 volts on signal .

 

[and0r]

Yeah I see the rod which controls it. The TPS is a moving part. And it helps knowing its potentiometer.

Anyway, I took her out for a spin after recalibrating the TPS. Bad idea. The transmission slammed really hard during the 3-4 upshift after only giving it the very slightest of throttle. I heard a brief screeching, like a band or bearing being crushed by metal or something. Idk. or maybe it was the converter clutch. All the shifts have been hard and late and slamming, from 1-2, and 2-3, but not as hard as that one 3-4 upshift. Im really worried. I don't want metal or clutch material floating around in my system, I hope I didn't break anything.

 

[stamp11127]

The tps might also be the Hall Effect type.

 

[Dewayne]

Sounds like you have more than a bad sensor there . Can you scan for transmission codes.

 

[and0r]

Despite its other problems, the 4r100 is pretty beefy asside from its valve issues, but that one upshift felt like the clutch or final drive pack was just being rammed in hard by a rod or something, idk how to explain it. I also dont want to do anything which disturbs that one weak faulty snap-ring (i think its a snap-ring for the final drive) which is a known problem with the 4r100. That snap-ring easily gets dislodged.

********, the official service manual really shouldn't be vague here.
This is turning out to be a huge problem, and it's not fair.

Lesson of the day, DO NOT recalibrate a faulty TPS.
Once you clear your shift pattern, it seems the vehicle is trying to learn how to shift with a bad TPS telling it the wrong things.
This could very well ruin your transmission even if you barely give it throttle while at speed.

 

[and0r]

No other problems.
I'm scanning with a good OBD reader on PC, and using Forscan, which is like one step below the actual factory IDS software.

I get codes for the TPS, high output signal if i remember correctly, and also code for inconstant readings between the TPS and MAF, or something similar to this effect (dont remember the exact code description)