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Thread: Iacv idle control valve

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    Iacv idle control valve

    Are there any aftermarket options that could work on a ca?

    I am doing a bay rewire/tuck and would like to hide the idle control under the plenum somewhere, will be running nistune so will need idle control of some form.
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    You don't ask easy questions do you Rich ? Lol

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    Quote Originally Posted by pointz View Post
    Are there any aftermarket options that could work on a ca?

    I am doing a bay rewire/tuck and would like to hide the idle control under the plenum somewhere, will be running nistune so will need idle control of some form.
    I completelly binned aac and cold idle valves,idle is adjusted by throttle stop and stabilised by ign. timing at idle table. It work just ok. Only not perfect is cold start due to missing air valve,but just run litlle bit rough first second after cold start.
    note: my idle is set to abot 1200rpm, so if 900rpm idle is requested, cold start can be issue without help of right foot on the gas pedal...
    Last edited by raddy.; 08-11-2017 at 14:48.

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    Quote Originally Posted by raddy. View Post
    I completelly binned aac and cold idle valves,idle is adjusted by throttle stop and stabilised by ign. timing at idle table. It work just ok. Only not perfect is cold start due to missing air valve,but just run litlle bit rough first second after cold start.
    note: my idle is set to abot 1200rpm, so if 900rpm idle is requested, cold start can be issue without help of right foot on the gas pedal...
    This was exactly what i was comtemplating doing. Are you on nistune?
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    if your car works you could try unplugging it and see how you get on.

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    Quote Originally Posted by green_rs13 View Post
    if your car works you could try unplugging it and see how you get on.
    Stupidly lifted the engine before trying it !!
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    Move the air reg as well. Run feed hose from hot side to wherever you stuff them, T hose into air reg and idle assy, T hoses coming out back into one hose and run hose up to the air reg port on plenum.

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    Quote Originally Posted by pointz View Post
    This was exactly what i was comtemplating doing. Are you on nistune?
    yes, nistune...

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    Ready, what pcv set up have you got ?

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    Quote Originally Posted by Jonny Wilkinson View Post
    Ready, what pcv set up have you got ?

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    no oem pcv, just vent to atmo.

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    This is more for Rich as I'm sure you've worked all this out Raddy but, on the OEM setup, air is drawn into the plenum via the pcv valve when a vacuum exists in the plenum (i.e. when idling).

    If you've shut that off and the other "alternative" routes (IACV, cold air reg etc.) for air to get into the plenum, the only place it can get in is via the throttle body.

    If the butterfly is fully closed, no air can get in and it will stall. it will also put a lot of stress on the seals around holes in the throttle body that take the butterfly spindle.

    Setting the butterfly slightly open is quite a coarse way to set the air inlet at idle and, obviously, you can't change it for when the engine is cold except by pressing the throttle and opening the butterfly a bit more.

    We seem to spend a lot of time on here complaining about all the stupid nonsense that Nissan either fitted for no reason or because the EU made them but the reality is that fuel injected motors are more complex to make work than carbed models (which just constantly deliver the wrong amount of fuel lol ).

    Not having a go at anyone, just saying, we all (including me) are sometimes guilty of trying to make things simpler than they can be on the basis that simpler must be better, right ?

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    Cheers Jonny, i run vta breathers and pcv is blocked off.

    Change of plan now anyway i dome a purchase on something that means i can lose iacv amd cold start!
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    Map sensor ?

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    Or a set of carbs lol

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    Quote Originally Posted by Jonny Wilkinson View Post
    Or a set of carbs lol

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    Heretic!
    Blow or suck through? (Careful could just be making your heresy worse.)

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    The true answer to that is a question itself. Which has less wires ?

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    Quote Originally Posted by Jonny Wilkinson View Post
    The true answer to that is a question itself. Which has less wires ?

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    Map sensor!
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    Quote Originally Posted by pointz View Post
    Map sensor!
    but that also require an air temp sensor.

    Map sensor is an active device it requires a +ve feed, ground and has output.
    Temp sensor is resistor 2 wires.
    Map + Air Temp = 5 wires.

    Lambda AFM = 3 wires.

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    Quote Originally Posted by skyshack View Post
    but that also require an air temp sensor.

    Map sensor is an active device it requires a +ve feed, ground and has output.
    Temp sensor is resistor 2 wires.
    Map + Air Temp = 5 wires.

    Lambda AFM = 3 wires.
    Lambda + afm + iacv + cold start = many wires lol

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    Quote Originally Posted by pointz View Post
    Lambda + afm + iacv + cold start = many wires lol

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    What has the lambda sensor got to do with a 3 wire AFM? It may be called a "lambda" AFM but it's not dependant on the lambda, you could just as well connect to the 3 AFM pins on a 4 wire non-lambda AFM. What has the iacv and cold start got to do with air flow? Without them engine will just be a bit of pain to start and keep running until warm. If you are going racing it's not needed, Sunday and track days only it's not needed, daily driver utter PITA whatever air flow measure you use.

    A 3 wire AFM is all you need to measure the air flow. The the Nissan ECU may not like having the TPS removed as the alpha-n signal is used to check the AFM is sensible (fail this check and it goes to limp home mode) but other ECU's are possibly less fussed. AFM = 3 wires.

    If you use a map sensor then you are using air density x volume to estimate the air flow. Volume is from engine speed x VE map. Density requires both pressure and temperature. 5 wires.
    http://www.lightner.net/obd2guru/IMAP_AFcalc.html

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