The dreaded throttle position sensor

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docraymund

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Going back to your original post, if your truck seems to be struggling while going uphill but is not misfiring, I think you are right in suspecting a bad torque converter. Try inspecting it.
 

stamp11127

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I'm always looking for new things to learn. So how is he going to inspect a sealed torque converter? And how does the tc control line pressure and shift points?
 
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and0r

and0r

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FORscan is pretty in depth. It reports each individual module, such as GEM, ABS, OBD, PCM, IC, and a few others. I didn't see anything about a transmissions though, would that be part of the TCM module? Either way, the PCM is not showing any codes.
I would recommend that everybody here use Forscan and a BAFX OBD2 reader from ebay.
Or you can pick up a VXDIAG unit on ebay too for about 90$. It comes with "registered" Ford IDS software. This is full-on factory level diagnostics, including firmware flashing. (You need to provide the firmware though)

Anyway, I got the idea to cut away a slot in the stripped TPS mounting screw with a rotary tool with cut-off wheel, so I can unscrew the new slot with a flathead screwdriver. I'm probably going to try doing this tomorrow. And I have a quality set of extractor bits to fall back on in case it doesn't work.

Worse case scenario I have to pick up a new throttle-body.
Mine looks very clean by the way. The more I explore on this truck, the more evidence I find of the miles being totally original, which makes me very happy!

Does anyone know where to get these mounting screws for the TPS?
 
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stamp11127

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Apply heat to the bolt and come back with a small portable impact or you will mess the slot up. Use just a few wacks from the impact to see if it moves.
 
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and0r

and0r

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How do you get these mounting screws though?
 
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and0r

and0r

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Success!
But the degree of success remains unclear.

First off, I was barely able to break the screw free after cutting a slot all the way down, just a micro meter away from the base, and using the largest flathead screwdriver I had. I put all my strength into it, much more than I thought I had, and it finally broke free. I meant to take pictures of everything, but I was just totally determined to get my truck running again, so I just threw everything back together without taking pics.
I reused the screw since none of you will actually tell me where to get another one, it works fine. And I greased the screws with penetrating oil before they went it.

The first thing I noticed when taking her for the first testdrive was the transmission. Each gear was shifting perfect, better than it was before, even the 2-3 upshift was smooth as butter, and it had always been a little harsh before the TPS failure.
Launching the truck from a standstill was also good and consistent.. The torque was nice and girthy, I couldn't reproduce the flaccid, weak launches. Which is good.
Then I took her up a steep hill, to Mullholland HYW, which is paved, and her power was still not as strong as I liked. But was slightly better than before. I must have drove her around for 30 miles, testing all gears and just listening to the truck.

I noticed that after getting back down the hill to my street, the standstill launches were getting weak again, but the shifting was still good.
I think I know why these sensors fail. It's the heat.
I checked the throttle-body in my garage with the engine still running and it was damn hot. Everything was hot. It's a big engine.
I touched the sensor and it was damn hot too. It didn't burn me, but it was hot enough to immediately understand this temperature not being good for the plastic components of the sensor.
I'm thinking of wiring a nice, high-RPM PC fan and maybe even a heatsink directly to the sensor! I have plenty of spare fans and heatsinks lying around.
What do you guys think?

The temp is clearly too much for the sensor in my opinion.
 
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Dewayne

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As long as you installed a quality part you should be fine , I have seen too many people add unnecessary devices to their vehicle and cause problems . Had a guy install a high intensity fog light system in his truck once and wire it to the fuel pump circuit truck would run like crap under load with lights on .
 
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and0r

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I would look into wiring any 12v fan on the ignition circuit.

The engine is just way too damn hot for the sensor. Top half is all aluminum, the heads and intake. It sinks the heat from the iron block pretty niceley. The iron is very hard to cool compared to aluminum.

This sensor is just chintzy plastic with a variable resistor of some sort inside. At some point the heat must also directly effect the resistence on top of weakening any plastic housing or smaller plastic components. Heat plays a direct role in electrical resistence too. I'm tempted to cut open the old TPS sensor and look inside.

Which way should I cut it?
 
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and0r

and0r

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It's a little silly that Ford would just throw this sensor directly on a heated aluminum component this way. I don't think a PC fan will cut it either.

Probably need to throw on a small CPU water block cooler, like the ones for gaming computers.
 
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and0r

and0r

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The best option would be to extend the control arm of the throttle body to the sensor, to allow the sensor to be mounted further away from the throttle body, between a layer of insulation
 
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