r33 IACV how to wire into neo

[matt3579]

so my cars got a really high idle anywhere between 1500 and 2000rpm when warm.

ive fitted a otaku ffp originally we blanked the iacv and it ran okayish would start at 550-600 rmp and when warm raise to 900rpm a decent idle however when you give it some the rev would drop low enough for the car to die so we fitted the 34 neo IACV and it works sort of will cold idle at 2000 and sometimes drop to 1500 sometimes it wont i assume this is down to water going though my vented bonnet and sitting in the coolant lines as we have only connected the air intake (was advised thats all thats needed) that and the coolant lines would be a pain to plumb in. ive since purchased a r33 IACV to save me the hassle of plumbing in coolant lines however i have searched high and low and cant find how to wire it in. as the neo only has 1 plug a grey one the 33 iacv has 2 plugs and ive not a clue where to start with it really so if anyone could tell me how to wire it in that would be amazeballs cus ive ran out things to search (on here and google and other owners pages) and still no luck. 

 

thanks in advance 

[WMDC35]

It's been ages since I've played with that stuff but I think it's the purple plug.

The BOV may have also contributed to the rev drop issue.

 

[GTSBoy]

The Neo IACV has water through it to provide the heat to close the wax pellet for the fast/cold idle up. The R33 one is heated electrically. All you have to do is not hook up the plug that is connected to the heater and just hook up the plug that is obviously connected to the valve itself.

But there's a problem. If you don't heat these things, you will end up with cold fast idle all the time, because the cold idle bypass is quite large and you should not drive the IACV as closed as you need to to beat that.

[matt3579]

11 hours ago, GTSBoy said:

The Neo IACV has water through it to provide the heat to close the wax pellet for the fast/cold idle up. The R33 one is heated electrically. All you have to do is not hook up the plug that is connected to the heater and just hook up the plug that is obviously connected to the valve itself.

But there's a problem. If you don't heat these things, you will end up with cold fast idle all the time, because the cold idle bypass is quite large and you should not drive the IACV as closed as you need to to beat that.

so only 1 of the 2 plugs needs to be connected im not looking at it but from memory both iacvs have 2 pins plugs? i know they dont plug in so would i wire say the left to the left and right to the right or how would you suggest?

[GTSBoy]

If I have to google a picture of the R33 IACV so I can look at it and work out, FROM A PICTURE, which plug is which, I'm going to scream. One of them will clearly look like it connects to the bloody valve, and one of them won't.

[WMDC35]

Yeah I'm pretty sure it's the purple plug

[matt3579]

On 10/29/2019 at 11:10 AM, GTSBoy said:

If I have to google a picture of the R33 IACV so I can look at it and work out, FROM A PICTURE, which plug is which, I'm going to scream. One of them will clearly look like it connects to the bloody valve, and one of them won't.

i think you misunderstand what im asking, the plug on the 33 doesnt fit into the 34 plug both from memory are 2 pin plugs so what wires should connect to what, i know which plug to use and which not to but they are no plug and play so i will need to join some wires from what im told? my question is which wires go to what?

aplogies for any confusion 

[GTSBoy]

Yuh, my point was that there are two plugs, and one is clearly able to be worked out that it drives the stepper motor valve, and the other is easily seen to not be connected to the stepper motor valve and therefore must run the heater. It's not like it's a black box with no details on it.

I will also remind you that I said that if you don't run the heater on either IACV (either by putting coolant through the Neo one, or hooking up the heater on the vanilla one) then the cold start valve will stay wide open in both of them and give you a very high idle that the stepper motor part of the IACV will not be able to close down enough to get under control.

If you look in Nistune**, when the engine is warm and the cold start idle up valve is heated closed, the ECU should report the number of "steps" that the IACV is open and you really don't want that to go below about 30. It will do so if it is trying to fight the cold start valve.

**I'm not suggesting that you go and look in Nistune, just a general "you" to describe the process.

Here is a picture of an R33 IACV. Which connector do you think is wired to the stepper valve? Which one do you think might simply be a heater?

[GTSBoy]

Although, having said the above, and then having done 3 seconds of googling because I don't actually care about R33 IACVs enough....I think the purple one may be  a simple on/off solenoid for air-con idle-up. Look at the wiring diagram to see what is true!

 

From one of the many previous times that this has been discussed.

 

Edited November 1, 2019 by GTSBoy

[GTSBoy]

And just for completeness and correctness, to ensure that my small elements of misinformation above are covered over - the RB25DET uses the same type of separate air regulator that provides the cold start idle up as appeared on the RB20 and 26. It looks like this

So, the purple plug on the Rb25 IACV is not for a heater, it's definitely for the air-con idle up. The heater connection is on the air reg pictured above.

The Neo does away with the air reg as a separate thing and puts it into the IACV with water heating, as I said before. There is no air-con idle up as a separate thing either. It's just done through the IACV (as far as I can tell).