DaleClark

iTrader: (55)

Hey guys -

Have a friend with a clean '90 convertible, I just rebuilt the engine and it's running like a champ. It looks like the TPS has gone out, I will be able to fully test it with a meter this weekend to make sure.

Been looking into replacement TPS's, used is always a crapshoot depending on whether the seller can properly test it for dead spots with a meter. So I'm mainly looking at going new.

Turbo TPS's are substantially cheaper than NA TPS's, I think due to Japan only having turbo cars and there being more worldwide demand for the turbo part. NA is like $400-500 and turbo is about $280 or so.

I do seem to remember (I'm rusty on my FC stuff!) that the TPS's are identical save for the bracket. I think you can just bend the tabs that hold the two TPS sensors to the bracket to remove them and swap to the other bracket.

Am I remembering correctly? Any "gotchas" doing this? Easier/cheaper way to do this?

Thanks,
Dale

rotary#10

iTrader: (38)

I believe the brackets are the same on the S5 TPS. They look the same on mazdatrix website for referencing.

DaleClark

iTrader: (55)

I think they are mirror images of each other or something. I think Mazda had to make some changes since the NA throttle body is basically flipped upside-down.

Also, I THINK the wiring is identical. The plugs are physically the same except the NA has a black connector and the turbo has a white connector. I'll double-check the service manual on that one.

Oh, just looked on Atkins Rotary's site, you can clearly see the brackets are different:
Turbo: https://www.atkinsrotary.com/store/8...80-18-911.html
NA: https://www.atkinsrotary.com/store/8...0-18-911B.html

Dale

Pete_89T2

iTrader: (4)

It's been many years since I've messed with this, but the S5T2 TPS sensors themselves are identical to the S5NA TPS sensors. So if you want to buy the new (and cheaper) S5T2 TPS and use it in an S5 NA, it goes like this:

1. Take the dead/donor S5 NA TPS, remove the sensors from the original bracket without mangling the bracket in any way. Don't recall if they have removable snap-in plastic tabs, or if some grinding with a dremel tool was needed to free the sensors from the brackets.
2. CAREFULLY remove the new S5T2 TPS sensors from their bracket without mangling them.
3. Mount both of the new S5T2 TPS sensors on the old NA bracket, making sure you don't mix up full range from narrow range physical locations on the bracket. May need to get creative with an adhesive or JB weld to secure them to the bracket.
4. Crack out the FSM/wiring diagram to figure out how to wire the two sensors to the 6 pin connector plug so it will be compatible with the S5 NA wiring harness.

DaleClark

iTrader: (55)

Thanks Pete!

I just dug into the wiring diagram, the wiring harness plugs are identical so that's a plug-and -play at least. All 6 wires are wired identically and the outputs go to the same ECU pins.

For reference, there are 6 wires to the ECU. 2 are BR/B wires (brown/black stripe), those are grounds. 2 are BR/W (brown/white stripe), those are 5v input from the ECU. 1 is B/G (black/green stripe) and that is full range to ECU pin 2G. 1 is G/R (green/red stripe) that is narrow range to ECU pin 2F.

I seem to remember the TPS's were just held onto the bracket with 4 crimped-over tabs. May be a little adhesive in there too, can't remember.

Dale

DaleClark

iTrader: (55)

So to follow this up....

I did this on my friend's car last weekend. Wasn't that bad.

Hard part on the non-turbo is just getting the damn TPS off the car. You maybe could do it without removing the TPS but it's far easier to do this on the bench.

There are 2 10mm bolts on the side holding the TPS in and a Phillips head screw on the bottom holding it in. The screw is the kicker. My friend made a tool out of a combination wrench and a Phillips head bit - put the bit in the closed end of the wrench with some sort of glue or RTV and was able to break the screw loose. At that point it unscrewed by hand. You could replace that screw with a regular 10mm bolt that would make it much easier in the future - we didn't have one in his garage so we just reversed the process to install the screw back in place.

While the TPS is still in the car make careful note of which sensor is the narrow range and which is the wide range. If you open the throttle all the way the narrow range will no be touching any linkage and will be fully out at around 30% throttle or so, the full range will be contacting through the whole range.

That done and both on the bench, you just need to bend the little tabs up to remove the sensors one at a time. They are held in with 4 bent tabs, it's best to straighten 2 tabs on one side then slide it out. The less you bend the tabs the better. Also, before you start removing sensors, figure out which is wide and which is narrow and maybe mark them. I also used the colors of the wiring going to the sensor to keep which is which straight. The tabs are relatively soft and bend easily, I used a screwdriver and a small hammer.

Putting the turbo TPS's onto the non-turbo bracket I had to slit the heat shrink tubing on the wiring to have the wiring comfortably go to each sensor, again not a big deal.

Once bolted on, we fired up the car and had a dead steady idle, checked everything and fine-tuned and had a great, solid idle with no bouncing or anything. The ECU had a stored TPS code so I cleared the codes out and the car was good to go.

To be clear, there is NO wiring changes needed. The wiring side is literally plug and play. Just make sure the correct sensors go on the correct spot on the bracket and you're good.

This is a great way to replace a non-turbo TPS for far less money. Also, if you got your hands on a low-mileage JDM turbo TPS this is an easy way to swap it onto a non-turbo. With any used TPS, check the resistance range for the full sweep to see if it's bad or not.

Dale

j9fd3s

iTrader: (3)

were the brackets actually different, or just this little harness thing?

Jaiyurai

iTrader: (30)

DaleClark

iTrader: (55)

Yep, brackets are WAY different. The TPS plungers themselves are identical and the wiring is exactly the same. Only trick is making sure the correct TPS goes in the correct spot.

Dale