IACV help.

[kelz240]

Can anyone tell me where the 2 smaller ports on the IACV hook up to? Got the big port hooked up but cant find any info on the 2 small ones. It wont let me upload a pic to point them out. thanks for the help

[zombiewolf513]

They connect to the water hardlines that run under the intake manifold

[kelz240]

Awesome. Thanks for the quick reply zombiewolf! i appreciate it.

[zombiewolf513]

NP. Good luck.

[jr_ss]

To add to this, you must hook them up otherwise you risk idle issues.

[Silv1401]

To add to this, you must hook them up otherwise you risk idle issues.Why is that?

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[S14rebuild]

Why is that?

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Idle is relevant to engine temperature

[Silv1401]

Any clue why they got rid of said coolant ports on the late models, then? I have a 98', and the only barb on it is for vac.

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[zombiewolf513]

It changed to an ECU controlled, electronic solenoid. ECU reads the water temp from the sensor

[Silv1401]

Makes sense. Was that the case with the SR20 as well?

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[zombiewolf513]

s13 sr: water controlled, s14/15 sr: ecu controlled

[Silv1401]

Thats good to know, and helpful for something I've been trying to decide on.

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[jr_ss]

The S14/15 have the coolant line/idle up feature built into the throttle bodies as well. The wax media holds the throttle plate open wider during cold starts, similar in function to the S13 IACV.

[Silv1401]

What wax media?

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[S14rebuild]

the waxstat is a very primative unreliable fast idle mechanism.

when the coolants cold, the wax shrinks and the plunger is resting low. this allows the sprung loaded fast idle arm to push against the throttle mechanism and keeping it slightly open, hence "fast idles" at 1400rpm during cold starts

once the engine & coolant is at 82C, the wax expands to move the plunger up against the sprung fast idle arm. this retracts the fast idle arm away from the throttle mechanism and allows the throttle to fully shut therefore warm idles at 750rpm.

over the years of heat cycle, the wax tends to stiffen up so it doesn't expand as much or at all even when the engine is fully warm, so the mechanism remains stuck in "fast idle" mode.

so the first symptom of a seized waxstat from date of manufacture is remaining stuck in fast idle when engines warmed up.
I say "from date of manufacture" cos when it seizes, most ppl take it to a garage and would mostly just tighten the "idle bleed valve" to lower the warm idle speed as a bandage, even though the throttle is still propped open by the fast idle mechanism.

another thing is the IACV at the front of the TB is an electronic backup of the mechanical fast idle mechanism.

the solution is to disable & discard the old waxstat mechanism from the throttle, clean and check the IACV so its functioning 100% and then readjust the idle bleed screw till it warm idles at 750rpm.

Google is your friend

[LtSlayer]

the waxstat is a very primative unreliable fast idle mechanism.

when the coolants cold, the wax shrinks and the plunger is resting low. this allows the sprung loaded fast idle arm to push against the throttle mechanism and keeping it slightly open, hence "fast idles" at 1400rpm during cold starts

once the engine & coolant is at 82C, the wax expands to move the plunger up against the sprung fast idle arm. this retracts the fast idle arm away from the throttle mechanism and allows the throttle to fully shut therefore warm idles at 750rpm.

over the years of heat cycle, the wax tends to stiffen up so it doesn't expand as much or at all even when the engine is fully warm, so the mechanism remains stuck in "fast idle" mode.

so the first symptom of a seized waxstat from date of manufacture is remaining stuck in fast idle when engines warmed up.
I say "from date of manufacture" cos when it seizes, most ppl take it to a garage and would mostly just tighten the "idle bleed valve" to lower the warm idle speed as a bandage, even though the throttle is still propped open by the fast idle mechanism.

another thing is the IACV at the front of the TB is an electronic backup of the mechanical fast idle mechanism.

the solution is to disable & discard the old waxstat mechanism from the throttle, clean and check the IACV so its functioning 100% and then readjust the idle bleed screw till it warm idles at 750rpm.

Google is your friend

Hey, don't mean to steal the tread but I recently developed a very similar problem after replacing all the lines in my intake manifold as well as collector and manifold gaskets. The car started right up and I can't hear any vacuum leaks anymore and she runs well under boost again.

I didn't open up the wax element or even touch the IACV mechanism that sits on top of the log part of the intake. a caveat to my idle problem is that the car is rish at idle now as well. I'll have baby backfires at idle. The timing was set months ago following instructions in the FSM, the dots on the CAS. Car currently idles at 1500 but drives well. I got a little pb blaster on the paper gasket that stuck out from below the idle set screw maybe that? s13 sr20det, I have all the lines and didn't delete anything. used to idle maybe 50 or 100 rpm high but was always a nice strong idle not twice what it should be lol.

any ideas? thank you

[S14rebuild]

You boost leak test? The throttle body likes to leak at the shft seals also did u tryn making idle adjustment on the iacv? Theres an adjustment screw

[LtSlayer]

I haven’t checked for a boost leak but I’m running rich. Figured it’d be impossible to run rich with a vaccum leak. I haven’t adjusted the idle screw because it worked fine before and I didn’t want to adjust it if it was something else. I hooked up both coolant feel and return to the IAVC as well as to the throttle body. Think the connection to the IACV could be bad? The connector

[S14rebuild]

In all honesty i have deleted coolant lines to the iacv and the throttle body. I experienced 0 negative effects. This is my case.

Also neither of those would cause a rich issue. I would be looking at a maf or injector problem if its reading rich at idle.
Car shouldnt be that high at idle..800-900 where it should be

[LtSlayer]

I never had a problem with either before, same injectors as well as maf

[LtSlayer]

Car warms up at 1250 but once warm idles at 1500/1700 it’s weird

[zombiewolf513]

coolant temp sensor

[LtSlayer]

That’d make it run rich and high idle? Does anyone know the intake collector torque spec by chance? The temp sensor should be by the thermostat right? Around the head gasket passenger side front of the bay?

[S14rebuild]

Its on the upper intake manifold. Theres 2x

1 is a one wire connector (for the cluster)

Otjer is a 2 wire connector. Thats the one ur looking for

[S14rebuild]

https://www.google.com/search?q=ka24de+coolant+temp+sensor&tbm=isch&ved=2ahUKEwiIs7bJu6btAhVJT1MKHZC-DBsQ2-cCegQIABAB&oq=s14+ka+coolant+temp+sensor&gs_lcp=ChJtb2JpbGUtZ3dzLXdpei1pbWcQARgAMgUIABDNAjo ECCMQJ1DgHViAImCCLmgAcAB4AIABmAKIAagEkgEFMy4wLjGYA QCgAQHAAQE&sclient=mobile-gws-wiz-img&ei=_ubCX4i8EcmezQKQ_bLYAQ&bih=678&biw=412&prmd=sivn#imgrc=39y0x2RI5unouM&imgdii=YacEsdEjm8Eu9M

[LtSlayer]

I found it but my SR reads temp fine. I’ll replace it since it’s cheap but any other ideas? Does anyone else have any ideas? Do I have to recalibrate TPS if I disconnected it?

[S14rebuild]

I found it but my SR reads temp fine. I?ll replace it since it?s cheap but any other ideas? Does anyone else have any ideas? Do I have to recalibrate TPS if I disconnected it?

Guage sensor and ecu sensor are diffrent. What ur seeing on the cluster and what the ecu reads can be off.

Have u tried to pull codes?


No u dont disconnect the tps to recalibrate it, use a multimeter to backprobe it and set to .46 closed throttle

[LtSlayer]

Guage sensor and ecu sensor are diffrent. What ur seeing on the cluster and what the ecu reads can be off.

Have u tried to pull codes?

Got you, my consult port isn?t hooked up and some genius decides to take off the light that blinks and the switch to activate it. I kinda read you can jump it but I already read someone fried their ecu does this and I?m not electrically inclined. Harness is a bit ratty. Anyone have an E5 ECU I can borrow?:rofl:

[LtSlayer]

update, I replaced the coolant temperature sensor with one from a 91 240sx because I read that was a suitable replacement idk if right or wrong. The idle is still high but now the car is running lean instead of rich. I also cleaned the maf, could be what made it read lean? I really don't know what to try next. If the AFR was solid I would just adjust the idle set screw and call it a day but it was too high now too low. The fuel pressure regulator seemed ok as well. I'm in socal so i dont really need the cold start wax element thing. Woe is me