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Discussion Starter · #1 · (Edited)
If you are reading this bold line, it means I just finished writing this. It took a few hours and I have not proof read it yet, so it could contain minor errors, spelling mistakes, etc. I'll try to proof read it the day after posting. I've been looking at this for too long.

This write-up will detail how @Glumpy3 and I successfully repaired the failing throttle bodies (TBs from here forward) of a pre-lp (2004) Gallardo.

I wont be going over diagnosing this. You need to actually figure out that your TBs are bad before you do this.

One very important thing to note before diving in:
This is not a procedure to take lightly. The process is not overly complicated, but you are permanently altering the TBs of your car. If you do this incorrectly, or you experience a failure after completing the repair, you have a real chance of losing control of the car depending on how it fails. In the process of figuring this out, I nearly crashed my car. I talk about this later. I'm not exaggerating, this is a serious job.


The TBs on the pre-lp Gallardo, as you probably know already, are crap. They are a 100% failure rate item. Lamborghini is not making them anymore, and as they continue to fail the supply is getting smaller and smaller. On a long enough timeline, there wont be any used ones to choose from. Not only that, but swapping out your bad TBs for used ones just means you’re spending $2k+ for parts that already have a limited lifespan. The alternative is to send your TBs to Xemodex to be rebuilt. There is nothing wrong with that, and in a lot of cases it’s the way to go. I think its important for people to be able to repair their own cars, though. I have been unable to find any documented post anywhere on the internet of someone DIYing this on a Gallardo, which is what motivated me to get it figured out.


As a brief overview this is what you will be doing:
  1. Remove the TBs
  2. Open them up
  3. Scrape out the old potting material
  4. Replace OEM TPS with a Sacer touchless TPS
  5. Wiring it up
  6. Calibrating voltage
  7. Resealing
  8. Reinstalling
Some background on why this repair is possible. The TBs in our car are very similar to the ones in certain Volvos. They are NOT 100% identical, but they are similar enough for this to be possible. The volvo unit has different software, a different wiring harness, the volvo ECU expects a different value from the Volvo TB, but otherwise they're the same.

Volvo had a bunch of TB failures just like our cars do, except volvo is a real major car company, so they had to actually address it unlike Lamborghini. The issue with the TBs is that they use a contact design. A metal prong contacts a graphite strip. The location of the metal prong on this strip tells the car how far open the TB butterfly is. Over time, this strip wears down. Either it wears down to have bare spots, or it has build up/tear out which can cause "noise". On my car this resulted in erratic throttle response and revving in neutral. Volvo fixed this by switching their TBs over to a contactless design. This design was manufactured by Sacer. This fixed the problem. Our problem is that, for the reason I mentioned earlier, cannot just swap in a Volvo TB. We can, however, purchase the Sacer TPS and swap it into our TBs. That is what we will be doing in this guide.


Things you will need:
  • Sacer TPS or TPS replacement kit (Check ebay.)
  • Torx bits
  • Pick set
  • Sharp blade
  • Pry tool
  • Multimeter
  • Dremel
  • Compressed air
  • RTV/sealant
  • Woodworking clamp
  • Solder, soldering iron, probably flux
  • 10mm socket/wrench
  • Lots of time
  • Probably some more things I’m not thinking of.


Start by removing the top half of the intake, intake hoses, disconnect the TB wiring harness, undo the 4 bolts holding them on, and pull them off the car and over to a workbench.

Flip the TB upside down and take a look at the bottom of the unit. You will see a gray/white sealant around a rectangular piece of metal. I used a razor blade to cut the sealant all the way around, and then pried it off with a plastic pry tool. If you did not buy a replacement, be careful not to bend it beyond repair. Its pretty flexible.
299251



With that off, you should now be looking at this:
299252

The green potting material is covering up the contacts that we need to access. In the above photo I have outlined the areas that have to be removed. Do not remove the potting material by the harness connector or the area with the orange piece sticking out. An automotive pick set or a dental pick will make quick work of this. Its surprisingly easy. This is what it looks like coming out:
299253


Once you have the potting removed on both sides, we can remove the old TPS. This is the point of no-return because the OEM TPS is spot-welded on the contacts, something you probably cannot redo in your garage.

Start by identifying the correct side of the TB. One side is a motor, the other side is the TPS. If you accidentally remove the side with the motor you’re going to probably be buying a new TB. The side with 3 contacts is the side you want to remove. Unscrew the 4 torx screws holding the TPS in, and start prying it just slightly away from the TB. Be careful not to snap the black plastic. I was able to pry the black plastic away from the TB, and then use pliers to separate the contacts. You can see the spot welds in the photo below. Do not cut the contacts. Just pull them apart and they will separate.

299254


From here, if you want to, you can inspect your TPS. I wont be covering this in detail, but you can disassemble the TPS unit to get at the conductive graphite strip. Mine had a bunch of buildup which was resulting in my TB issues, yours might have that, or it might have bare spots. Hold it up to a light to check for bare spots.
299255



That concludes the easy part.

The Sacer TPS we will be installing is a different design than the OEM. It is contactless, which means there is no graphite to wear down. Instead it uses a magnet to read the position of the butterfly. The dimensions of this TPS are slightly different, though. If you try to attach it to the TB right now, the metal shaft on the TB will get in the way. We need to cut that. Do not cut it all the way off, but cut it a few millimeters above the nut. Here is what mine looked like after the first cut (This was too tall, but its the only photo I took)
299256

It is important at this point to test fit the TPS. You do not want the top of the shaft to even slightly touch the TPS. You can check for this by bolting the Sacer magnet to the shaft, attaching the new TPS, screwing it down to the TB, and manually rotating the butterfly with your hands. If it is scraping, you will probably be able to hear it. You can also check the underside of the TPS for score marks. It is very important it doesn’t make contact with the TPS. On my TB, with the magnet installed, the shaft was slightly lower than the nut.
299257


Once you have it cut, you can remove the nut with a 10mm socket. Make sure to blow out all of the metal debris from inside the TB. Any metal dust or shavings will mess with the Sacer magnet. Put the magnet over the shaft and bolt it down. You’ll probably be removing this multiple times, so don’t Loctite it just yet. You will notice that the shaft and the sacer magnet are both keyed, but they have some play. This will be important later. This is how you will tune the voltage of the TPS.

We are almost ready to install the sacer TPS, but like I said, you will be removing it multiple times through the voltage tuning process, so do not solder anything yet. Straighten the contacts with needle nose pliers, place the TPS over the TB, screw it down, and make sure the contacts are pressing up against one another. You want them to be applying pressure against one another so you can test the TB. Route the wire like I have it below. My contacts are soldered, but that’s because I didn’t have a guide to follow. Ignore that.
299258



Image limit. Continued in next comment.
 

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Discussion Starter · #2 · (Edited)
With the TPS temporarily installed, we now need to wire it up. The wiring we do in this step will not need to be be undone and will be permanent, so take your time.

Set the TB so the wiring harness side is opposite to you. Now look at the side with the 5 pins. The second pin closest to you is the one we will be soldering the TPS wire onto. The pin with the wire going into it is the one I'm talking about in the photo below:
If you look on both sides of the contacts, you will see two metal ridges. The one near the top of this photo is solid. The one near the bottom is hollow. The contact you want is the 2nd closest to the hollow ridge.
299261


We need to separate ONLY this contact. Not all 5, just this one. This is a huge pain in the ass, but its possible. Again, it is spot welded, so you cant desolder it. Enough prying and you’ll get it. I wound up finding a tiny chisel and hammering it between the two contacts. This was a stupid idea. It worked, but I could have badly damaged something so I’m not going to recommend it. The below photo is taken from the opposite side of the TB compared to the last photo. Dont let it confuse you because the broken contact in this photo is further away.
299262
Some kits come with the TPS wire pre-stripped. If yours didn’t, then strip the insulation off the end. DO NOT cut the wire. If you do cut it, you can still finish the job, but youll have a harder time tuning the voltage. Don’t cut it. Just strip the insulation off the end.

Pry the two contacts apart, make sure they are clean, (You don’t have to sand down the spot welds) and tin both of them. At the same time, tin the TPS wire and slip some heat shrink tubing over it. Now clamp the TPS wire between the two contacts and solder them together. Make sure this is a good joint. You wont be happy if it breaks. I put heat shrink tubing over all 5 contacts just to prevent them from shorting one another. The correct way to do this would be to re-pot them.

You’re about done, now. Time to tune the voltage. Here is how the tuning process works.

Below is an Ms paint drawing. This is the top view of the magnet, looking down on the shaft. The red is the magnet, black is the shaft. You may remember that the magnet had some freeplay around the shaft. You can rotate the magnet a few millimeters in either direction. In one direction, your voltage will decrease. In the other, it will increase. This is how you set the voltage. You have to remove the TPS, unbolt the magnet, rotate it, bolt it back down, put the TPS back on, and test it. Repeat until you get it right. This is the worst part of the entire process. If you have a way to apply voltage to the TB, that is the way to go. I was unable to find a pinout and did not want to fry anything, so I didn’t do this. I’ll explain what I did in a minute. I will also explain how to read the voltage.

MS paint drawing:
299263



I spent 2 days trying to figure out what the correct voltage was. This is not documented anywhere online or in any Lamborghini service manuals. @Glumpy3 measured his OEM TB voltages and got 1.36V and 1.41V. Keep in mind, though, his TBs were going bad. I started working within this range and found that my car worked perfectly, just like stock, at 1.399V. In reality the car has a range It can function within. I don’t know what that range is, but if its anything like the Volvo TB units (which is what is in our car), its probably between 1.38V and 1.42V. My 1.399V worked, so that is what I’m recommending. Again, sample size of 1. I have to recommend you also test voltages in this range, but my 1.399V worked. I want to repeat myself once more to make this absolutely clear: the voltage that worked for me, may not work for you. The volvo guys sometimes come up with different functional voltages. I have to recommend you test different ones instead of just setting to 1.399V and being done.

I also know what incorrect voltage does, because that is how I almost crashed my car. Initially I set the voltage to 1.5V on both TBs. This resulted in the car idling at a very low RPM. I was driving it and it felt like it had 200 horsepower. After a while I started getting a “Low Battery” light. I thought it was my battery. It was actually because the engine was struggling to keep going due to the idle RPM being so low. The engine was cutting out, but I didn’t know it at the time. When I was getting close to my house the RPMs dropped all the way down to 450 and the car stalled. Without power brakes or power steering, this heavy car is hard to steer. I missed my fence by a few inches and even standing on the brakes I wound up a few millimeters away from driving straight into the side of my house. I was lucky and this part is important. If I was on the highway I surely would have hit another car.

Another thing to note. On my car, in order to get the correct voltage, I had to cut the shaft at an angle so I could rotate the magnet more. Do not do this until you test the voltage on your car. I am a sample size of 1. Once you cut an angle into the shaft, you cant go back.

This shows how you have to cut the magnet. Again, looking down from above:
299264


Now onto how you can test the voltage. If you have a way to apply 12v to the TB and you can find a pinout, great! I didn’t. So here is how I did it:

You first have to understand how the car tests the TB. When you put the car into Aux2, it runs a bunch of tests. If you’re quiet you can hear them happening. One of these tests is to make sure the TB is responding. When you turn the key to Aux2, the car will briefly open the TB to 100%, then close it again. Its over by the time the “OK” appears on screen. The car is stupid and does not care what the voltage is, it just wants to make sure it responds. This makes measuring the voltage difficult, because you cant be inside and outside the car the same time. If you want to stay married, you also cant ask your wife to sit in the garage for 6 hours while you do this. I came up with a setup to do it on your own.

First, the contacts you have to probe are the two outer contacts on the TPS side. The contacts with the heat shrink coming off of them are the ones I’m talking about:
299265


I did not have alligator clips which would fit, so I made my own ghetto probes out of wire lengths. I used slightly shrunk heat-shrink to easily slip them on/off the contacts:
299266


I also did not want to keep screwing the TPS on and off, so I got a woodworking clamp. I clamped the TPS down so the contacts were touching one another. That’s all that matters.
299267


Now you’re setup to measure the voltage. Plug the TB into the car, set your meter to DC volts, get it hooked up to the probes and set it on your exhaust “shelf”. I propped a phone above the multimeter, and set it to record a video.
299268


With the phone recording, get in the car, turn the car to Aux2, wait for “OK’ to display, shut it off, and check your recording. You will see the voltage go from 0v -> Xv -> 0v. The highest number is what you care about. That is the number you want to get in the right range, or what I’ll be calling 1.399v.

Your next task is to figure out which direction increases the voltage and which direction decreases the voltage. Undo your entire rig, remove the TPS, unbolt the magnet, turn it all the way to right, and retest. Repeat, but turn the magnet all the way to the left. Now you know the range you’re capable of getting without cutting the shaft, and you now know which direction increases/decreases the voltage.

From here on, this is what you will be doing until you dial it in to 1.399v. Repeat until you get there. Good luck.

Once you finally have the voltage right, all you have to do is reassemble the unit.

Tin the 3 contacts on the TPS and the TB. Solder them together. Torque the bolt down and Loctite it. I didn’t remove it, I just dripped Loctite over it and let it seep into the threads. Screw down the TB. Tape the TPS wire down so it doesn’t get inched, and seal the metal panel back to the TB. I chose to put adhesive heat shield under the TB because I didn’t want the solder joints getting too hot. I also put heat shrink around all the contacts. Again, the right way to do this would be to repot it.
299269
You’re done! Wasn’t that easy?

I’ve been writing for hours and have to stop. Here are some supplemental resources:

Has anyone here done a TPS swap or installed a XeMODeX...

Volvo s60 P/N 8644345 2001 non-turbo ETM pictures
 

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Discussion Starter · #3 · (Edited)
FAQ
  • The sprint booster doesnt solve this. It isnt even a bandaid fix. If your TBs are going bad, it will amplify it. If your car is revving its self up in neutral and you have a sprint booster. REMOVE IT. I promise you the problem will be improved. It will still be there, but it might be more manageable
  • You cannot plug-and-play volvo TBs. The wiring harness is different, and all of my research has led me to believe the internal components are different enough that the ECU would have trouble. Also, the OEM volvo voltage probably would not be correct for the Gallardo. With that said, Volvo released a fix for their TB issue. Their fix is the reason we can buy the Sacer TPS units. The fixed Volvo units were touchless TPS and used Sacer as an OEM component. This might have a better chance of working if you got the pinout right, but I havent tried it and honestly it might be more trouble than its worth.
  • You cant swap to LP560 TBs without an entire ECU swap or a piggyback unit. Someone has gotten the swap working, but they need a Syvecs ECU, so its very expensive and somewhat defeats the purpose. If you already have an aftermarket ECU, it still isnt easy, but it is technically possible.
  • Your TB doesnt care if its dirty. There are a lot of posts on here where people are talking about ridiculous cleaning regimens with their TBs. I read a post where somebody said they spent hours cleaning them with precision dental tools. Unless you have measurable layers of grime or deposits all around the TB, your car doesnt know or care. I would bet all of the people who "fixed" this by cleaning the TB actually fixed it by unplugging and reseating the electrical connector.
  • You do not need any calibration procedure for this conversion to work. Its a very simple process, so as long as you show the car the voltage it wants to see, it will work. There is some misinformation floating around about a re-learn procedure. This wont make your incorrect voltage setting start working. It just wont.
  • xemodex does not do anything special. They also dont know the correct voltage for these. They modified their VW test bed to work with Gallardo TBs. The procedure you're planning to do is the exact same procedure they do, except they built a testbed to run the TB outside of the car so they can get it done a lot faster.
 
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Why I love this forum. Thanks GoatPuncher, awesome troubleshooting, info and write up. Quite happy I have a 2008 though!
 

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How do you know if the TBs are going bad, just bad/rough idle and engine lights as Glumpy's link suggests? Amazing work btw.
 

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How do you know if the TBs are going bad, just bad/rough idle and engine lights as Glumpy's link suggests? Amazing work btw.
The tell tale is the idle hunting that some shops even consider "normal for gallardos" if your car revs up and down at idle its likely this issue.

Do your due diligence though, make sure plugs, coils, vacuum leaks, etc are not an issue. I personally have no CELs in my 07 gallardo, but i am rather particular and needed to have it idle well. (Sprint booster, like Goatpuncher said, makes the idle surging much worse, EVEN IF its "Off". I had to physically unplug mine to notice a difference. )
 

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Great write up and well done!

The same problem affects the 3200 Maserati and has a similar remedy - in fact there is a company in the UK that has done lots of these on Maseratis so would imagine they could attempt the Lamborghinis has well if people were unsure about doing it themselves.

 

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Very nice job done by both of you!
I have ordered two kits and will jump into this in a month.
How is it possible to tighten the bolt without changing the position of the magnet!!? It must be twisted?

I talked to a friend at Volvo where I work and he has done it four times on Volvos.
He doesn't measure any voltage. Just start the engine, it runs really bad. Sometimes he has to pump the gas pedal. Then he cut the ignition and restart. After 5-6 times it has adapted itself and runs perfect.

I don't think it is that easy for us, in that case you have notised, but it would be great, wouldn't it. Too bad that Lamborghini didn't implement self adaptation.
 

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Hi, thanks for this precious post. My workshop has a guy who also repairs these TBs and it will get repaired soon as the jerking now is so strong that it is almost impossible to start without jerking. I have to accelerate so slowly when starting that the cars behind me get pissed off at the lights... Also it is impossible to do fast maneuvers from stand still like turning left, sometimes when it start jerking the car stalls. Happened to me last time when turning left, the car stopped on the middle of the road, so dangerous driving a car with this problem... It stalled a total of 4 times this month.

In the process of figuring this out, I nearly crashed my car. I talk about this later. I'm not exaggerating, this is a serious job.
@GoatPuncher could you please describe what happened when you nearly crashed the car? The TB's opened 100% and got stuck?
 

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Discussion Starter · #16 ·
Hi, thanks for this precious post. My workshop has a guy who also repairs these TBs and it will get repaired soon as the jerking now is so strong that it is almost impossible to start without jerking. I have to accelerate so slowly when starting that the cars behind me get pissed off at the lights... Also it is impossible to do fast maneuvers from stand still like turning left, sometimes when it start jerking hard the gearbox releases the clutch too early and the engine just stops. Happened to me last time when turning left, the car stopped on the middle of the road, so dangerous driving a car with this problem...



@GoatPuncher could you please describe what happened when you nearly crashed the car? The TB's opened 100% and got stuck?
From the first post:
I also know what incorrect voltage does, because that is how I almost crashed my car. Initially I set the voltage to 1.5V on both TBs. This resulted in the car idling at a very low RPM. I was driving it and it felt like it had 200 horsepower. After a while I started getting a “Low Battery” light. I thought it was my battery. It was actually because the engine was struggling to keep going due to the idle RPM being so low. The engine was cutting out, but I didn’t know it at the time. When I was getting close to my house the RPMs dropped all the way down to 450 and the car stalled. Without power brakes or power steering, this heavy car is hard to steer. I missed my fence by a few inches and even standing on the brakes I wound up a few millimeters away from driving straight into the side of my house. I was lucky and this part is important. If I was on the highway I surely would have hit another car.
 

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Great, great info in here! I've sent this to a few customers of mine and it saved them a fortune. Appreciated.
 

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Wow, such great work and kudos for passing your learnings on so eloquently. I have an 08 so I think I’m somewhat immune to the symptoms but I thoroughly enjoyed the read.

two quick observations: many many mechanics I’ve spoken to on both my 08 G and97 Diablo swear by fastidious cleaning of the butterfly valves, as you also mentioned. This must be deeply ingrained over the years. Second, just above your two red and black drawings you mentioned cutting the shaft but then also cutting the magnet. Typo? Curious, could you have taken a Dremel and cut a flathead screwdriver slot across the end of the shaft to aid in turning the shaft without removing the nut?

anyway, great job!
 
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