Always (almost) dies on idle

[plundccre]

My 2001 QX4 almost always dies when at idle at a stop sign or when stopped in traffic. Everything is normal, idling around 950 - 1000 and then it just dies. Starts right up again. Runs fine in all other conditions. Originally thought it may have been a fuel flow situation. Changed the filter and ran a few cans of fuel line and injector cleaner through the tank with no improvement.

Any thoughts on why it would be dying on idle only?

[chukel]

Any service engine soon light. Scan the power train and retrieve codes. That will be a good way to start.

[Buzzman]

My 2001 QX4 almost always dies when at idle at a stop sign or when stopped in traffic. Everything is normal, idling around 950 - 1000 and then it just dies. Starts right up again. Runs fine in all other conditions. Originally thought it may have been a fuel flow situation. Changed the filter and ran a few cans of fuel line and injector cleaner through the tank with no improvement.

Any thoughts on why it would be dying on idle only?

Sounds like the beginnings of a failing IACV.
If you run it too long with a bad IACV, you'll damage your ECM.
I'd replace it (the valve), even if you're not 100% sure that's the problem.
They will fail after 15 years, and you don't want to deal with having to repair the ECM.

[atraudes]

Make sure you replace the IACV gasket as well. I heard a theory on here a while ago that coolant leaks into the chamber containing the valve which is what ends up killing it. It may not be the only cause of death, but it's a damn good idea to replace that gasket while you're in there.

[plundccre]

I ran a search for any codes with my OBD II and its not throwing any.

I'm not familiar with the IAC valve. Where is it located on a 2001 QX4?

If the IAC is going out is stalling only at idle a symptom? I have no other issues. No hesitation on acceleration, no noises, etc. It just idles smoothly at around 750 - 800 and then just cuts out. Embarrassing and dangerous in stop and go traffic or at a stop light. The part is reasonable cheap enough (around $100) but I hate to throw money at something if it isn't the problem.

Is there any way to test the IACV without any specialized equipment?

Thanks

[atraudes]

The Engine Control (EC) section of the FSM on page 414 will show you where it is (attached to the bottom of the throttle body), and give you some testing procedures (I think they're pretty limited). The valve's responsibility is to open or close as needed to ensure the engine is getting exactly the right amount of air when idling (throttle plate is closed), so your symptoms resemble an IACV failure. The only thing holding me back from saying it definitively is that I'd expect the engine to lug a bit before dying, but I could be wrong.

Look at it this way: replacing the IACV is something every single R50 owner should do at this point in the car's life, even if they're not having problems because they will eventually. When it does rear its head it will be much more expensive.

[Buzzman]

Look at it this way: replacing the IACV is something every single R50 owner should do at this point in the car's life, even if they're not having problems because they will eventually. When it does rear its head it will be much more expensive.

I couldn't agree more.
Replace the IACV. Period.
Even if it turns out to be not the problem, it's a good investment.

When mine started to fail, I dilly daddled around for a month trying to figure things out, and trying to avoid spending the money.
My procrastination ended up costing me a lot more in time, money and aggrivation. I should have just replaced the valve.

[QCtech]

I would take the intake tube and see inside Throttle valve while somebody accelerate the car to see how dirty it looks. MIne went good just with cleaning, but is a 2003 and totally different from yours. I would start by cleaning, doing relearn process and check for codes.

[1998Baja]

MAF sensor clean or replace

[QX4ME]

MAF sensor cleaning is a good start. It happened to my other SUV (RX300) when it randomly died at low speed like leaving parking lot just before getting on street. I cleaned the MAF sensor and symptom disappeared. I used to clean MAF sensors on all my cars whenever I like to, not when symptom occurs. I never replaced one as they are just dirty

[RR425]

Mine sometimes feels like choking on start or at a light (rpms drop to around 500). I replaced to fuel filter and it got better. But didnt think much of it. Never stalled.

Is the IACV a simple bolt off/on replacement?

And is the Hitachi one the OE?

[atraudes]

Yes, Hitachi is OE. Some notes on my experience here. Beyond that, all you need to do is disconnect the air ducting, undo the four allen bolts holding the throttle body on, and disconnect two small cooling lines. Pretty straightforward. You'll probably want to clean the throttle body while it's out too, so have some throttle body cleaning spray and an old toothbrush handy.