quorton

I have an S14 240sx with a SR20DET

I installed a larger TB last weekend, one from a SR20DE, so its 60mm instead of 50mm.

But after the install, my rpm was way to high, 2000 rpm at cold and 1500 rpm at warm. I tried adjusting the TPS, I had it at 0,42v, after adjusting all the way, the RPM was still at 1000 rpm, and the tps at 0,1v.

Then I read something about the idle control valve. So I set the tps at 0,4v and turned the idle controle valve to set the rpm at 750 - 800 rpm (after using datascan to 'lock' the timing).

So now my rpm is oke, but my main question now is, what does the tps sensor do ?
If I adjust the sensor the rpm goes up or down, which made me think (not knowing about the idle control valve) it was meant to control idle.
But that is what the idle controle valve is for, so how come the rpm goes up or down with the tps ?
And how important is the tps voltage ?
The manual says it needs to be between 0,35 en 0,6 volt, which seems a pretty wide range to me.

If someone can enlighten me on these things I would appreciate it.

Btw, there is small vacuum hose going to the throttle body, with the hole coming out just at the valve, what does that do.
A friend of mine also put in his new TB and he didn't have this vacuum hose.

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g6civcx

The Throttle Position Switch (TPS) detects the angle of the throttle. As you open the throttle, the TPS signal increases in voltage. This lets the computer knows how to manage the engine.

Do you have a picture of the vacuum hose you're talking about?

quorton

I know the TPS senses the position of the throttle, hence the name.
My main question is how do I know which is the correct TPS voltage.

If I set the TPS to 0,35v then I can adjust the RPM with the idle control valve.
But if I set the TPS to 0,6v I can also adjust the RPM with the idle control valve.

So what's the point ? how do I know I selected the right TPS voltage ?


At the bottom of the TB there are 1 or 2 small pipes, one is usually blocked off, but the other one has a hose attached to it, I'm now told it goes to the carbon cannister, but I'll have to check that. If so, it has got something to do with emissions, something the US version probably doesn't have.

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ManoNegra

You have the FSM? The voltage values that correspond to the various stages should be there.

Hmmm... I don't follow you there. You mean hold the trottle so that it read that volage?

Again, don't follow you. You need a voltmeter to read the signal off the TPS. Use a T-pin to rape the appropriate wire off the TPS connector and clamp the voltmeter to it to read the signal.


US version DO have EGR canisters same as SRs. Most people don't bother keeping them since the swap is illegal anyways.

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quorton

FSM ? you mean the tech manual ?

No, you can adjust the TPS by turning it.
I can turn it so it reads 0,35 or turn it up to read 0,6v. The higher the voltage the higher the idle RPM.
In either case I can set the idle RPM to approx 850 with the idle control valve and the car runs fine.
So my question was, how do I know which tps setting is correct ?

I use datascan (consult software) to read the TPS value, so no need for a voltmeter.

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