P2135 - Looks like TPS is bad

[pzy3339]

Last night
Driving at 70 mph through hills on cruise control I got a thunk and dropped out of CC, also flashing wrench on the dash for a moment. Manual throttle did not feel right but I could keep going. I noticed when I let off the throttle engine braking was much stronger than usual. Later tried CC again and it would not function. I only came to 1 stop and shifting through the first few gears was not normal. Reminded me of how an RC transmission works if you are familiar with gas RC vehicles.About 30 minutes freeway and 15 city.Not hard to get it home but it was a little nerve-racking, I was thinking I had a transmission issue.

This morning
I hooked up a code reader, something worth having at home for $40, and got P2135(TPS sensor, etc). I then searched here and read through a few threads prior to starting work on the vehicle .

I tested the throttle and pedal first. With the car on (engine not running) and intake tube removed (so you can see the throttle plate) I pressed the pedal and had someone stand in front of the vehicle watching the throttle plate move. Everything was as it should be. After that I tested the TPS.

 

[pzy3339]

To test the TPS I used an ohm meter on the 4 pins for the connector. With the TB on the engine I moved the throttle plate by hand with my ohm meter on the connector pins. I noticed between 2 sets of pins the variance in resistance was not as variable as I felt it should be from WOT to about 65% throttle. The resistance of the potentiometers should be fairly linear. Mine appears to be bad.

I removed my throttle body, then removed the TPS with little issue. Used some penetrating oil and a hex key in a 1/4" socket on a 1/4” ratchet. If you have a good feel for how much torque you can apply to this screw head you will quickly see if you are going to require heat. I did not, It’s about 60f today. I also inspected my vacuum lines and wiring. Everything else looks fine so I ordered a motorcraft TPS which I should have tomorrow morning. ~$100

 

[pzy3339]

My overnight order came late so the next day I bought an off brand TPS, it did not work at all. Engine would not run. I could see it was inferior in design and craftsmanship right out of the box. Took it back and put the original back in to get me to work.

Got the Motorcraft part Wednesday and put it in. Shifting definitely feels more responsive and accurate, mostly during freeway driving.

I had been having some minor shifting issues the past few weeks and had been concerned about the transmission. Quite happy this sensor has made such a difference.

Really hoping to get 250k miles out of this vehicle before I have to replace it. 177,200 on it at the moment and running like a champ.