Idle Switch

[kurupt]

Ok...i have solved every problem with my car now, except this one. My car ran like hell, (idle surge), i unplugged the idle switch, it immediately ran better. After a week now of driving around with it unplugged, the car runs great. I am selling my car, now my question is can i just leave it unplugged and sell the car, or is this a mistake? Here is a pic of what i unplugged, the 1g underhood diagram shows it as the idle switch. Thank you.

 

[steve]

The idle switch triggers the ECU into doing various things like cutting the fuel if the rpms are too high at idle or making the ISC emulate a dashpot on deceleration. Pulling the switch just masks the real problems.

Steve

 

[eclipse90gsxt]

Your idle surge is probably a bad coil or more on the ISC, idle control sensor. Its under that sensor your showing. Get a haynes manuel and a oham meter and check the ISC. www.vfaq.com also has a faq on it.

I forgot if its volts or ohams/but those meters have everything on them.

 

[steve]

You measure the resistance (ohms) of each winding in the two coils.
Jeff Lucius 3S page on ISC/IAC's is better than what's on the VFAQ site. He describes how the ISC is used, how to check it and almost all of how to rebuild one.
http://www.stealth316.com/2-isc-iac.htm One notable difference, DSM's don't have an external dashpot so the ECU emulates one with the ISC.

A bad ISC can cause idle surge but so can a number of other air leaks. The idle surge FAQ goes into some detail http://www.dsm.org/how-tos/tttt/tttt3.html but the bottom line is too much air bypassing the throttle plate at idle.

Steve

 

[eclipse90gsxt]

^^
I was to lazy to look that all up :laugh:

 

[steve]

The sad thing is I didn't have to look it up...

Steve

 

[kurupt]

Pulling the switch just masks the real problems.

Steve

What do u mean by 'real problems?' i am going to buy a digital multimeter this Fri. i found out how to test properly in vfaq.com. i will post the results on Sat. Thanks again...

 

[kurupt]

Daaamn...i thought that said 'makes the real problems'.... my bad...

 

[Archer Fabrications]

I have a 2g and when i slapped on my 1g TB i never even noticed that needed to be hooked up. Do the 2g connectors work with the 1g sensor? I've been driving without it plugged in since my 6 bolt swap and haven't really had any issues yet? It looks just like a spade connector correct. I think someone zip tied the harness side plug once upon a time, I'm gonna post back with a picture to make sure i have the right connector going to the idle switch.

 

[snowborder714]

2g idle switch - built into 2g TPS (4th pin)
1g idle switch - external to 1g TPS (only has 3 pins)

As long as you're still running a 2g TPS, you're fine.

 

[Archer Fabrications]

2g idle switch - built into 2g TPS (4th pin)
1g idle switch - external to 1g TPS (only has 3 pins)

As long as you're still running a 2g TPS, you're fine.

yeah i believe i am on the 4 pin 2g tps, i just sold another 4 pin TPS i better check mines not a 3, it is plug and play with my harness, so i think i got 2g still

 

[snowborder714]

They're interchangeable, so you won't know unless you actually look at it.

 

[Archer Fabrications]

They're interchangeable, so you won't know unless you actually look at it.

its 4 pin

 

[Calan]

The idle switch still has to be mechanically adjusted to set the throttle plate gap though. And, it's a very sensitive adjustment; something like 1/8 turn between right and wrong.

 

[Archer Fabrications]

The idle switch still has to be mechanically adjusted to set the throttle plate gap though. And, it's a very sensitive adjustment; something like 1/8 turn between right and wrong.

the throttle stops where its supposed to, i have it exposed at the moment and it closes all the way while still touching the 1g switch. dont wanna be having a cracked throttle all the time after all, that would be an annoying idle surge battle. do you know of a measurement exactally? i have calipers i can measure something the same distance and put it between the stopper as an adjustment to make sure i have the correct measurement. it does stop closed and hits the stopper at the same time though.

 

[Calan]

the throttle stops where its supposed to, i have it exposed at the moment and it closes all the way while still touching the 1g switch. dont wanna be having a cracked throttle all the time after all, that would be an annoying idle surge battle. do you know of a measurement exactally? i have calipers i can measure something the same distance and put it between the stopper as an adjustment to make sure i have the correct measurement. it does stop closed and hits the stopper at the same time though.

This is the factory procedure:

To adjust the switch. You unloosen the lock nut of the switch, turn it all the way out counterclockwise. Make sure you loosen up the throttle cable as well. Get you meter put on a good ground and the positive on the switch, turn switch in unitil you get continuity, when it is constant;turn the switch 15/16 of a turn clockwise, stop and tighten up the lock nut and your done. Make sure you tighten your throttle cable.

In all reality, you are trying to get the throttle blade to close, but not stick. It's trickier than it sounds to get correct.

Brian may have a better answer for you.

 

[snowborder714]

This is how I adjust them typically.
http://www.dsmtuners.com/forums/151826306-post2.html

 

[Blkapache01]

Hey, my apologies for bringing up an old thread but does anyone know where I can get another ISC switch? It's been off and on working but today I started the Talon and no matter how many times I adjusted it, it went from idle surge to just straight high idle. It was working fine a few weeks ago and now just surging and high idle.

 

[steve]

Which part? There is a Idle Position Switch and there is a Idle Speed Controller but no ISC switch.

If you follow this thread and it's links you likely learn how to address the problem you're describing with surging and high idle. The 1G NA throttle body is slightly different but works the same as the turbo version.

 

[Blkapache01]

It's the stop switch. Looks like a miniature spark plug that you have to back out and adjust and keeps the throttle from clicking all the way in.
It was working fine a few weeks ago after some adjusting but now, it goes high idle again when I take the plug off to adjust it and when I plug it back up, it's surging.

 

[pauleyman]

It's the stop switch. Looks like a miniature spark plug that you have to back out and adjust and keeps the throttle from clicking all the way in.
It was working fine a few weeks ago after some adjusting but now, it goes high idle again when I take the plug off to adjust it and when I plug it back up, it's surging.

That is a simple continuity switch. Check continuity to ground and check all your grounds associated with that switch. There is a bracket at the throttle body itself and another from intake manifold to firewall

 

[steve]

Sounds like the switch is making continuity to ground since it's surging when connected and having a high idle when disconnected. So you need to look into why is idling high. Was the switch screwed in too far holding the throttle open, is the throttle cable too tight again holding the throttle open, is there a vacuum leak, did the ISC go bad in an open position causing too much bypass air, Did the FIAV fail stick in it's cold idle position allowing too much air to bypass, etc?