Crazy Idle

[bizzle]

Lately my car has been going all wacky when idling, mostly when coasting in neutral to a stop. If I dump it into neutral at any speed, the idle will sometimes drop so low that the engine stalls. I watch my ScanGauge II and the idle will go between 400-650 when this happens. Sometimes when I get to a stop the idle then balances out to the normal ~750 rpm. I drive the car about 90 miles a day and some days it's fine, others it's not.

Relevant info:
Spark plugs have about 20k miles and are NGK and the stock plugs, no idea how old the coils are.
Engine has about 150k
NO CEL or any other codes
No mods on the engine that I know of except the head was rebuilt with stronger retainers and springs (I think) when Blown 05 Si owned it and the cams were replaced about 20k ago due to pitting.
No noticeable loss of power at any revs.
I have not done the idle relearn jobby yet.
If it's happening, I can go into my ScanGuage II and FORCE CLEAR codes (even though there are none) the idle normalizes.

Any idea of what I should check first?

[tinman5]

I'm running an A2 swap and she did that while driving home from work. Scared the crap out of me honestly because I had no idea where to even begin looking.
I keep an obd multi scanner in my dub that showed "idle control valve malfunction" the car drove perfectly fine it just idled really high then would bog down or vice versa.
Fortunately my warranty covered the repair and the tech cleaned out the Vtec solenoid and threw on some fresh plugs as well. Not bad for a $50 deductable.

[Manny Kid 15]

Check your iacv and clean it or replace it...


Sent from MANNY KID 15 using Tapatalk

[bizzle]

Is it safe to spray the insides of the IACV with carb cleaner beings it's got plastic parts? Or is it ok because I'll be removing the plastic part anyway?

[Draw7Seven]

They make IACV cleaner products sold at auto parts stores. I don't know how different they are than carb cleaner, but it might be worth a couple bucks to just buy it. Check out this old thread, some of the pics are down but Doug did a thread on cleaning the IACV.

http://www.ephatch.com/forum/showthread.php?43337-Cleaning-the-IAC

[bizzle]

So I still haven't had a chance to rip apart the TB but I did change the oil and figured while I was at it, I'd run a tank of gas with Seafoam. Problem went away so I think it's an issue with the fuel system. I'll see today if it's still gone when it runs straight gas.

[Her-Name's-Ally]

check the coil packs

[bizzle]

I still haven't had a chance to look into it... but it's still happening. I noticed with the cooler weather it's not as bad.

[ep32424]

check the wires at night time, spray some water if it spark it means the wires are no good.