SomeGuy_sg

Searched around for a while but still nothing much came up. I was wondering if any one on the forum has replaced their stock S4 plunger type TPS with a rotary/turn type TPS.

I have been thinking about this for a long while now. The stock TPS 1/3 throttle is WOT. A replacement would allow better resolution and may be better mileage and throttle control.

I have found some cable/string type TPS. But given the heat and fatigue i doubt that would last.

SomeGuy_sg

RotaMan99

I have also been wanting to do this but there are a few issues.

S4 TPS is narrow range meaning it reads about 5-6kohm at 25% throttle. If you use a rotary type TPS, if you are talking about the ones that are on newer vehicals, they travel the full length of the throttle opening. So even if you got one that that was within range, it would still be 5-6k ohm at 100% throttle instead of 25%. So for a good portion of the throttle travel, the ecu may think the throttle is closed.

SomeGuy_sg

I see. So is there really no way to increase throttle sensitivity unless you change out the ECU with the TPS.

RotaMan99

Now what do you mean be sensitivity? If you are asking about how to get the full range of throttle opening measured, then you would have to swap out ECUs with a S5 but that would a huge head ache considering the S5 ECU has a bunch of "limp" mode features and some sensors are not backward compatible.

On my S4, I swapped on the S5 intake mani and TB. This ment I could install the S5 TPS bracket. The 2 sensors that were on the bracket were no good so I put 2 S4 sensors on the bracket instead. They work exactly the same. Except one TPS measure the full travel of the throttle opening and one measure to 25% of throttle opening. That one I have hooked up to the ECU and the full range one I have hooked to my SAFC.

My question is, I wonder if the Rteck for the S4 N/A will allow you to run a full range TPS instead of the narrow range. I don't see why not since its programable.

I find the narrow range usless.

Here is something interesting that I found out quickly after installing the S5 TB. I used to have the S4 TB on the S5 mani for a while.

While using the S4 TB and TPS. I had to adjust the TPS to 1kohm or just under for it to be correctly adjusted. No big deal. Now when I switched to the S5 TB, I had to adjust the Narrow range to 1v which is a bit higher the 1kohm. I forget how much, in fact I should measure the resistance to see.

So now, If I have to work on anyones rx7 and they have a S5 TB on a S4 engine. I adjust the TPS to 1v. Works perfectly every time. If they have a S4 TB on a S4 engine, I adjust it to 1kohm, again, works perfectly

SomeGuy_sg

Sensitivity here, meaning a better range of throttle. I do agree that narrow range is really useless here. I would think surely that an aftermarket ECU, ie;Rtek or Microtech... would allow you to be able to adjust for the full range of the throttle. But would it work with the S4 TPS. If not, how would some one mount the TPS on an S4 TB?

The previous owner has installed a MT8 on my S4 already. But with the narrow range of the TPS, over 1/3 throttle the ECU would see it as WOT and inject the according fuel. Which in turn is bad mileage -_-"

As i see it there would be 2 ways of mounting a newer wide range TPS.
1. Modify the throttle shaft and a custom mount so as to mount the TPSensor straight on to the end of the throttle shaft
2. Use the cable/string type TPS mount it back on to the stock location and add linkages on to the throttle shaft.

NZConvertible

It's pointless changing the TPS for one with a completely different signal. The ECU will simply be seeing the wrong info. There is nothing that could be gained from this.

HAILERS

The TPS isn't used to calculate the amount of fuel injected. Your wasting time and effort.

The AFM is used for fuel amount delivery.

SomeGuy_sg

NZ; I know that the stock ECU would see it as a error. So we were thinking more along the line of a ECU and TPS upgrade.


Hailers; Isn't the amount of fuel and ignition timing calculated by AFM/MAP/MAF and TPS along with various other little things.

NZConvertible

IT wouldn't see it as an error as such, it would simply see a signal that's wrong and act wrong as a result.

RotaMan99

So what is the TPS for then? The ECU must use both to get the correct amount of fuel into the engine.

RETed

Most ECU's use it just for primarily throttle transient fuel enrichment.
The stock ECU uses it for some other minor things.

What you propose is a long route...

Why not just go standalone EMS, and this is all taken care of for you?


-Ted

RotaMan99

I use my full range for my SAFC. I was hoping the Rtek for s4 N/A would allow for full range ot be used but I just found out that it is only programmed for the narrow range.

SomeGuy_sg

Been searching around the forum and found an interesting pic. This is how you would
mount a TPS for a haltech. Thing is that would cancel out the S4 OMP.
Mmm.... Interesting thou

Icemark

I used a early 90's Toyota Supra/Truck TPS for a while when I was playing with a Megasquirt on my vert. It was a round, linear pot that I just made a bracket for and mounted on the front side of a S4 non turbo Throttle body.

Adjustment was the only thing that was a little tricky.

But I gave it up when I pulled the megasquirt out and sold the car.