IACV ?'s

[turboh224g]

I have searched on different forums and can't seam to get a straight answer on the IACV/coolant line removal. Here is the situation. We have a track only s13 coupe with an SR. We have tried to simplify everything as much as possible so that if we do have a problem at the track things will be easier to fix. All unnecessary wiring is gone. All emissions components are gone. If it is not necessary for the car to function properly it is no longer there. We have had a few problems with the coolant lines from IACV under the mani. Can these be removed, etc? New motor is going in over the winter including Power FC, and custom IM. If I can get rid of one more thing I want to. Any one have the right answer? Thanks,
JKP

[modulation]

What is the question here?

I have 1 vacuum line from intake manifold to FPR, as well as the brake booster line still connected.

I removed any coolant lines to the throttle body.

That's all you need.
You can remove IACV and weld up all holes. Remove EGR and weld up all holes. I bought a after-market intake aluminum ebay intake and welded up all emission holes on there (except for one to valve-cover.)

Start-up in cold weather is a bit tricker, but if you has nistune or something similar you can tune for no IACV.

[fliprayzin240sx]

All its for is for cold idle. The IACV opens up slightly when it senses the coolant is cold, and bumps up the idle. When its up to temp, the idle settles down to whatever the IACV is set to.

[nieko]

This might be a dumb question, but how exactly do you set the idle if there is NO iacv?

Just thru the pfc or something?

[lok]

i used a block off plate that i had a friend cut on a CNC plasma.

i just looped the lines with a piece of 5/16" hose.

you set the idle by adjusting the throttle plate adjuster screw and resetting the TPS voltage back to stock .45v.

[modulation]

All its for is for cold idle. The IACV opens up slightly when it senses the coolant is cold, and bumps up the idle. When its up to temp, the idle settles down to whatever the IACV is set to.

That's not correct. The ECU uses the IACV any time the car is idle, not just when the coolant temp is cold.

[Walperstyle]

I've heard of people putting a small crack in the throttle body to get around it.

maybe someone that has done it can tell us what they did.

[s14unimog]

I'm not sure how you completely remove it but I do know that without coolant running through the IACV, the car won't idle worth a crap... I always have to bleed mine, when I work on the coolant system, to get it to idle calm.

[modulation]

I've heard of people putting a small crack in the throttle body to get around it.

maybe someone that has done it can tell us what they did.

Small crack? What?

As some one above said there are throttle body place set screws. These little allen head screws that you can screw in/out and it will prevent the throttle body plate from closing all the way. This is how you set idle.

Once you get idle happy, then you adjust the TPS sensor to read in the proper voltage range.

It sounds complicated but takes 5 minutes in real life.

Idle changes by 200-300 rpm's depending on the flucation in temp of 30 degrees or so. For example mine is at 700 when it's like 70 out, but 900 when it's in the 40's.

[datsunnazi]

You can take it off, just say "good bye" to any type of cold start high idle, high load idle bump, and poor idle when coming to a stop. But if you say that it's for a track car, none of those really are necessary. i would just say delete it in my honest opinion.

[turboh224g]

OK, lots of help. I expect idle issues but it is a track car. I just don't want it to be too crazy with the 272's and no iacv. I will talk to RT about tuning on d-jetro and see if they are worried.
JKP

[modulation]

You can take it off, just say "good bye" to any type of cold start high idle, high load idle bump, and poor idle when coming to a stop. But if you say that it's for a track car, none of those really are necessary. i would just say delete it in my honest opinion.

You're correct about "say "good bye" to any type of cold start high idle, high load idle bump" but are incorrect about "poor idle when coming to a stop," unless you mean only when the car is cold.

I've had no IACV for a year now, and once the car is warmed up (say 5 minutes of driving,) coming to a stop makes no difference in my idle...
If you set your idle right with the throttle body plate then when you start coming to a stop, your idle will just drop to where you set it and stay there.

[jakerps13]

This isn't reinventing the wheel! People have done this for years. However if you want to remove the iacv you'll need some cold start tuning like others have mentioned.

Unlike the KA the SR uses coolant to adjust idle speed via engine temperature. So if you get rid of the hoses to the iacv, it's rendered useless. Except if you uplug it you can still use it to adjust your idle via the screw instead of adjusting your throttle plate and readjusting your TPS.

[rnkelly]

From what I've gathered, you set your idle with this procedure (s14 sr20det);

Start engine and let it idle until engine is warm.
Hold throttle at 2000 RPM for two minutes and turn off the engine.
1. Disconnect TPS
2. Rev engine 3 times above 3k to lock it in timing mode
3. Check what it is idling at, if it is not at ~750-800, adjust it with the screw on the IACV.
4. Check timing with a gun
5. Make adjustments if needed
6. If adjustments are drastic, reset idle accordingly
7. Plug in TPS

But my question is;
Where is the throttle body Allen key screw set at for this?
Is the TB supposed to be full closed and the IACV handle everthing?
Or do we have to fiddle around with both to get it just right?

[modulation]

From what I've gathered, you set your idle with this procedure (s14 sr20det);
But my question is;
Where is the throttle body Allen key screw set at for this?
Is the TB supposed to be full closed and the IACV handle everthing?
Or do we have to fiddle around with both to get it just right?

1. On the throttle body is the Allen key screw, it's freaking tiny, but you'll see it, it's a stud with a allen head on one end you screw it in/out and it opens/closes the throttle plate a tiny amount.

2. If you have a IACV, the TB should be closed all the way (At least on a ka24de, but I'd guess for all nissans of our era.)

3. No, my TB was closed when I "converted" to no IACV, and I had to open it.

[M11's]

I don't have the metal or tools to make block plates, is there any places to get them online? I did find the egr plate but thats it.

[jspaeth]

OK, lots of help. I expect idle issues but it is a track car. I just don't want it to be too crazy with the 272's and no iacv. I will talk to RT about tuning on d-jetro and see if they are worried.
JKP


You said it all there. No IACV and 272s will be fun hahahah. Surely the car will drive fine in gear, but getting that to idle correctly will be fun....

I have a PFC and I love it, but the main feature that I want that it doesn't have is DIRECT control over the timing when the car is idling and also direct control over the parameters that govern how the IACV works (including temperature dependence).