IACV removale and leave it out?

[93_jdm_fd]

Just wondering if I can remove it and leave it out somehow without causing any running problems? Right now when I start my car it idles low cold and higher when warm. I can't drive my car until this valve is opened or closed which ever by the ecu.

[Skym]

IACV is a automatic choke. It adds extra air to intake plenum on top of what AACV does when throttlebody butterfly is closed. IACV is open and closes as engine warms up (uses heat from engine, hence why it's mounted close to engine, voltage). AACV controls amount of air into intake plenum when engine is warm. You could borrow a manual choke setup from I think was a early 80's Nissan Sentra. That's if you don't mind pushing knob in on dash as engine warms up.

IACV = Idle Air Control Valve, AACV = Auxiliary Air Control Valve

[93_jdm_fd]

I have a low rough idle when cold so I think the IACV is stuck closed not allowing and extra air into the intake during warm up, once warm it's fine. I might just take it off and clean it out or at least see if something is broken inside. It seems like a pretty fun job to.

[bobbo]

You have to take the manifold off which is a pain the first time and order the gaskets. Cleaning and testing them is pretty easy assuming you have the manual and I've got a post somewhere here on how to do it.

[93_jdm_fd]

I've had the manifold off before to reset the throttle stops and do some hose inspections. The gaskets are all brand new so I might pick up some of the spray gasket sealer to lightly add to the gaskets. I want to do it this weekend and don't want to wait two weeks for gaskets.

[bobbo]

Daryl would likely have them in stock and have them to you VERY quickly. Or your ideal will probably work fine too.

[93_jdm_fd]

Well it seems no matter what I get in the mail takes weeks longer than normal, lol. I have to try and fix it this weekend. I just can't stand getting up for work and sitting in my car for 15 min while it warms up. It won't let me rev past 2200rpm without stopping on the gas and that I will not do.

[bobbo]

Wow! Even the mail doesn't wanna go to SJ! Just kidding, I grew up in Quispamsis.
You can't rev past 2200 when the car is cold? Or are you keeping the revs below 2200 as a precaution when the car is cold?

[93_jdm_fd]

Moving back to edmonton next month and shipping my car out there, a little more parts available out there anyway. No I start moving and once I get to like 2200rpm it's like hitting a wall or driving around with the ebrake on. I know it's normal for the engine to run on it's cold start map or whatever but this is not normal. It runs really low and rough when cold and has no power at all in any gear until it starts to warm up. It used to start doing it when I hit 3rd gear around 2500rpm but now it does it starting off from 1st and hitting 2200rpm.

[bobbo]

That sounds like it's going into limp mode. IACV or AACV won't cause that behavior. Have you checked for codes? I strongly suggest going into Maple Leaf Nissan and asking VERY NICELY if they'd hook CONSULT up to your car and getting a scan and print out. Nissan here charged me $100 but they like to treat me like they're servicing an Infinity vs. a Nissan.
It'll tell you what your AACV is doing along with virtually all other functions. Also if they can do it when the car is cold you might be able to get more info as to what is going on.
That all is assuming you're still running the stock ECU.

[93_jdm_fd]

Yeah running the stock ecu, I bought another one and installed it last month and it still does the same thing. I will probably end up going over to nissan and seeing about getting it hooked up to their scanner. What would cause it to go into limp mode and cause it to come out of it when it's warm? I also check for codes every other day and find no stored codes.

[Skym]

ECU pulls ignition timing, runs engine rich initially when engine is warming up (can adjust ignition, fueling with Nistune). Once past certain coolant temp or revs, etc ECU switches out of this warmup mode. You can adjust what coolant temp, revs, etc via Nistune.

IACV can get sticky due to oil deposits from oil in blowby or via blown turbo oilseal (compressor side) in the past and IACV needs to be cleaned or replaced.

IACV can be tested via putting on a hot plate and adding voltage via battery. Then see how long IACV takes to close.

[93_jdm_fd]

I've removed and completely cleaned the AAC and it was pretty dirty so I'm guessing that same gunk will be in the IACV to. I would love to have nistune just to see what my car is doing myself and be able to tune it pretty easily. I will be removing the IACV tomorrow so I'll post up some updates.

[93_jdm_fd]

So removed the intake and IACV, it was pretty dirty but nothing broken inside which is good and bad I guess. Kinda hoping for something broken so I might have found my problem. Anyway cleaned it out and reinstalled everything. I won't know until I start the engine cold if it has helped any. Either way I still have the lumpy sounding idle that I was kinda hoping the IACV being dirty and maybe sticking would be causing my lumpy cam idle. I even for fun removed the intake valve cover to check again for any markings to indicate aftermarket cams and found no marks.

I have to adjust the AAC to 1200rpm so it will smooth out. If i set it to 1000rpm it runs rough and even lumpier but drives great, pulls hard, no hunting idle, perfect steady vacuum gauge needle hooked right into the intake manifold boost vacuum line, so I guess that means no internal valve seat problem. Anyway the search continues, maybe my rough cold start will be fixed, one problem at a time I guess.