Today I took my throttle body off to clean it and take some pictures (due to the lack of detailed TB photos here) only to find out that my throttle position sensor (or throttle angle sensor as called by the service manual) was broken.
I decided to document the process so that others may find some useful information and pictures here. I'm not an expert by any means.
I gotta give big thanks to Angus for pointing me in the right direction and giving me the info I needed to tackle this myself.
The TPS is not sold by Acura, and only comes with the throttle body itself. Luckily there are aftermarket options from companies such as Blox or Omnipower. They seem to be pretty standard amongst many Hondas and a replacement is in the $35-60 range. All the sensors I found said they were for 95-05 NSXs but I'm pretty sure they're all the same, and it worked fine in my 91.
Throttle Body Removal
This is pretty straightforward. 4 nuts, 3 wire connectors, 2 coolant lines, 1 vacuum line, and the throttle cable (if I'm remembering correctly).
Once you have it off it'll look something like this (as seen from the engine side):
Now would be a good time to clean it as much as possible.
I decided to remove the motor for the cruise control and the TPS, which are attached to the side of the TB. You must remove the big motor first in order to get the rest of it off. Once the motor is out of the way there is a large star key screw under it. Once this is removed the sides come apart and the springs and gears move once seperated and you'll probalby be afraid that you'll never get it put back together again. It took me a bit to get it reassembled afterward due to the spring loaded gears having to be lined up just right for the cover to even fit over top of it. It was easy to tell which way it went due to the grease that was between the 2 gears. I could tell exactly how they were meshed up before I took it apart.
You *shouldn't* even need to take that off in order to replace the sensor, but that would require you knowing if it is bad already. WARNING: I think once you split these pieces apart you wouldn't be able to put it back together wtih your original sensor in place due to the way you have to twist them to install since everything is spring loaded.
Once I had everything open I realized that the tooth on the throttle position sensor was broken. I touched it to see if bending it back up and gluing it in place would be possible and it fell off completely. It is entirely possible that I broke it while taking things apart. I just don't see how it would've broken in the manner it did, even if it was from wear & tear.
So I picked up an aftermarket sensor and proceeded to remove the broken one. The sensors in the US are attached with twist off bolts, meaning there's no way to just remove them because they have no heads. You have to notch them with a dremel and unscrew them. Luckily they're not that tight so it is't too hard.
The new sensor also comes with screws.
Be sure to read the directions that come with the new sensor. most of the stuff below will be in those instructions but I'll cover it briefly.
When you attach the new TPS make sure the metal prongs are around the plastic tooth. What you have to do is put it on then spin it around about half a turn until the screw holes line up.
The new TPS has slotted screw holes in it which allows you to calibrate it. Put the screws in but don't tighten them down all the way. You'll need a digital multi meter for this. You must adjust the rotation of the sensor until you get as close to .45 volts as possible. I trimmed a bit of insulation off the middle wire in the tps connector in order to read the voltage. You'll need to have the TPS sensor plugged in with the car turned on with the ENGINE OFF. Once you get the proper voltage tighten the screws, tape up your wires, and put the TB back on.
I hope someone finds this useful and that I didn't leave out anything too important or make any huge errors :biggrin:
I decided to document the process so that others may find some useful information and pictures here. I'm not an expert by any means.
I gotta give big thanks to Angus for pointing me in the right direction and giving me the info I needed to tackle this myself.
The TPS is not sold by Acura, and only comes with the throttle body itself. Luckily there are aftermarket options from companies such as Blox or Omnipower. They seem to be pretty standard amongst many Hondas and a replacement is in the $35-60 range. All the sensors I found said they were for 95-05 NSXs but I'm pretty sure they're all the same, and it worked fine in my 91.
Throttle Body Removal
This is pretty straightforward. 4 nuts, 3 wire connectors, 2 coolant lines, 1 vacuum line, and the throttle cable (if I'm remembering correctly).
Once you have it off it'll look something like this (as seen from the engine side):
Now would be a good time to clean it as much as possible.
I decided to remove the motor for the cruise control and the TPS, which are attached to the side of the TB. You must remove the big motor first in order to get the rest of it off. Once the motor is out of the way there is a large star key screw under it. Once this is removed the sides come apart and the springs and gears move once seperated and you'll probalby be afraid that you'll never get it put back together again. It took me a bit to get it reassembled afterward due to the spring loaded gears having to be lined up just right for the cover to even fit over top of it. It was easy to tell which way it went due to the grease that was between the 2 gears. I could tell exactly how they were meshed up before I took it apart.
You *shouldn't* even need to take that off in order to replace the sensor, but that would require you knowing if it is bad already. WARNING: I think once you split these pieces apart you wouldn't be able to put it back together wtih your original sensor in place due to the way you have to twist them to install since everything is spring loaded.
Once I had everything open I realized that the tooth on the throttle position sensor was broken. I touched it to see if bending it back up and gluing it in place would be possible and it fell off completely. It is entirely possible that I broke it while taking things apart. I just don't see how it would've broken in the manner it did, even if it was from wear & tear.
So I picked up an aftermarket sensor and proceeded to remove the broken one. The sensors in the US are attached with twist off bolts, meaning there's no way to just remove them because they have no heads. You have to notch them with a dremel and unscrew them. Luckily they're not that tight so it is't too hard.
The new sensor also comes with screws.
Be sure to read the directions that come with the new sensor. most of the stuff below will be in those instructions but I'll cover it briefly.
When you attach the new TPS make sure the metal prongs are around the plastic tooth. What you have to do is put it on then spin it around about half a turn until the screw holes line up.
The new TPS has slotted screw holes in it which allows you to calibrate it. Put the screws in but don't tighten them down all the way. You'll need a digital multi meter for this. You must adjust the rotation of the sensor until you get as close to .45 volts as possible. I trimmed a bit of insulation off the middle wire in the tps connector in order to read the voltage. You'll need to have the TPS sensor plugged in with the car turned on with the ENGINE OFF. Once you get the proper voltage tighten the screws, tape up your wires, and put the TB back on.
I hope someone finds this useful and that I didn't leave out anything too important or make any huge errors :biggrin:
