Gallardo sacer Contactless TPS upgrade Instructions

I suggest watching this video first, and maybe a few others, to get comfortable with how the process goes, and then following the instructions below when you actually do yours.

1. Remove the rubber intake hose connecting the airbox to the throttle body. This can be done without removing the airbox covers.

2. Unplug the throttle body plug

3. Undo the 4 5mm Alan key screws, incrementally, in a cross pattern.

3.1. Fully loosen the bottom screws, hold the housing with one hand, then fully loosen the top screws.

4. Take the throttle to a comfortable table to work at.

5. Using a scalpel or similar, cut through the silicon holding the aluminium cap onto the bottom of the throttle body.

5.1. Trim off as much visible silicon as you can.

6. Using a flat blade/scraper, carefully pry up the aluminium plate, working around the perimeter. Try not to bend it too much.

7. Using a small flat-head screwdriver, Dig out the green potting compound that surrounds the 3 wires/pins for the throttle position sensor. The TPS is on the right side of the throttle body when looking at it as it's mounted on the car.

7.1. The pins are reasonably robust, you can feel the difference when digging between hitting potting and hitting a pin, but be careful.

8. Split the TPS pins from the throttle body pins. They are spot-welded, and will not de-solder. They can be split using side-cutters to slowly peel/crack them apart, or using a small chisel. Applying some heat with a soldering iron does seem to help somewhat.

9. Remove the 4 screws holding the TPS to the throttle body.

10. Gently pry the TPS out with a small flat-head screwdriver, watch the pins to make sure they are actually disconnected.

You can optionally deconstruct your TPS at this point to see how bad the resistive strip is worn down. Mine looked completely fine.

11. Remove the potting around the second pin from the bottom on the stepper motor side, ensuring there will be enough space to keep the pins separated. <image>

12. Split the pins apart, gently increase the separation so that they are not going to contact each other again.

13. Loosen the nut on the throttle shaft, use vice-grips or similar on the faced section of the throttle shaft to hold it in place. It's on REALLY tight. Once loosened, snug it back up, but not super-tight.

14. The fun part. Take an angle grinder or dremel, and remove the non-threaded portion of the throttle shaft that was exposed after removing the TPS. Try not to hit the thread, but ensure that the shaft no longer protrudes past the face of the throttle body where the TPS attaches.

15. Test-fit the new TPS to ensure it does not touch the throttle shaft. To be extra-sure, screw in at least 2 diagonally opposite screws. Move the throttle blade by hand through its full range. Remove the new TPS and check for rub-marks on the hall-effect-sensor housing. If it rubs, you need to remove slightly more throttle shaft.

16. Remove the pre-loosened nut on the throttle shaft.

17. Put the new TPS magnet onto the throttle shaft. There is some rotational slop in it’s alignment onto the shaft. This slop is enough for the TPS to work or not work, and you will need to find exactly where the magnet should be. For me, having the magnet aligned as far counter-clockwise as it could sit worked. My first alignment attempt was fully clock-wise, and the car would not run. Tighten the nut enough that the magnet isn’t going to move. You can hold the throttle blade with your fingers, but be careful not to damage it.

18. Gently bend the pins on the new TPS a few degrees towards the throttle-side, and neaten up the alignment of the pins in the throttle housing, so that when the TPS is attached, the pins gently push into each-other. This will allow you to test the magnet alignment before soldering the pins.

19. Run the extra wire from the new sensor through the hole near the TPS pins, and over to the exposed pin 2 on the stepper motor side.

20. Attach the new TPS, ensuring the pins are touching, and the new wire is not pinched. Screw in all 4 screws.

21. Solder the wire to the exposed throttle housing pin 2. Ensure that the stepper side pin is not touching.

22. Re-assemble the throttle housing onto the car, being careful not to over-tighten the screws.

23. Plug in the throttle housing plug.

24. Turn the ignition on, scan for codes using an OBDII scanner.

24.A. If no codes, start the car, wait for check engine lights. 

24.A.A. If the car starts and idles, and there are no codes, congrats, go to 26.

24.A.B. If the car throws a code/shows a check-engine light, go to 25.

24.B If codes, something is very wrong, check your wiring.

25. Remove the throttle housing, remove the TPS, loosen the nut, pick another angle for the magnet, go to 20. I’d suggest trying both extremes first, then a mid-point, then 2/5ths, 4/5ths etc. If it still doesn't work, you may need to expand the range of adjustment on the magnet, this is “Good luck” territory.

26. Once the car starts and idles without codes, remove the throttle housing.

27. Optional but recommended: remove the TPS, add some thread-lock to the top of the nut/thread, re-attach the TPS.

27. Solder the 3 TPS pins, being careful not to melt the extra wire going past them now.

28. Optional: re-pot your pins. Not sure I can recommend this as it may cause a lot of swearing in the future if you ever need to open them up again.

29. Flatten out the aluminium cap as well as possible, and re-attach using some RTV, ensuring you haven't pinched the new wire. Clamp the cap while it sets, to keep it aligned.

30. Re-attach the throttle housing to the car.

31. Plug in the throttle housing plug.

32. Reassemble your intake hoses.

33. Enjoy.