| After the recent post about a Sentra IACV being compatible with the Z32 using an adapter, I went down a little bit of an idle valve rabbit hole and came back with some useful info to share. I was able to successfully clean the housing and upgrade the solenoids from a new VG33 IACV. Been installed for a few weeks now and happy with the results. Here is what it looks like all done and ready for installation: 
The VG33 IACV (23781-1W600) from late ’90s Pathfinders and early 2000s Frontiers has the same bolt pattern as the Z32 version. The issue is that the FICD placement interferes with the Z32 cam covers, preventing a direct bolt-on. The workaround is to swap the AAC and FICD solenoids into the Z32 IACV housing. Functionality seems the same, but the newer solenoids use updated connectors instead of the old wire clips. You’ll need to solder in new harness-side connectors, which are available from Wiring Specialties (links below). (Aftermarket VG33 IACV left, OEM Z32 IACV with new OEM Solenoids right)
 The main issue is the IACV housing itself, since that’s what actually gets dirty and causes idle problems. Early housings could be disassembled, but most are sealed with epoxy from the factory and are non-serviceable. However, I still managed to get the housing thoroughly clean using an Ultrasonic Cleaner. If you’re not familiar, look them up on YouTube — they’re useful for way more than just car parts. Here is the cleaning process I used: -Remove solenoids, gaskets, idle screw, and air pipe from IACV housing.
-Run the ultrasonic cleaner with your solution of choice (I like ZEP Citrus) for ~10 minutes with no parts in it to degas the solution.
-Drop the housing in along with any additional hardware bits like idle adjustment screw, air pipe, AAC screws, etc, and run a 30-minute cycle. The solution will likely turn black.
-Pull the housing out and clean around the internal spring and plunger with cotton swabs. You can rotate the spring and plunger with your finger to clean as much as possible. Be careful not to leave behind any cotton strands or debris. You can also swab down through the air pipe opening. Swab until the cotton swabs are coming back out clean.
-Run another 10–30 minute cycle. Refresh the solution if the first batch is filthy.
-Optional: finish with a short 5-minute cycle in rubbing alcohol and water.
-Dry with compressed air and verify internal spring/plunger action looks good, no sticking, consistently closing after pressing it in.
-Begin reassembling unit 
These are all J30, notice the Aluminum one on the right.
 The orifice with spring and plunger that need cleaning.
 Try and clean the entire surface of everything you can access.
 Notes on IACV Air pipes: Both Z32 and J30 housings work, but the J30 IACV doesn’t have an air pipe that supports the Z32’s air regulator, so you need to swap the Z32 pipe over to a J30 housing, or delete the air regulator entirely. The air pipes are press-fit and can be swapped either way; a dab of RTV can help seal but isn’t strictly necessary. Be sure to reinstall the rubber gasket between the AAC and housing on reassembly. 
WD40 Warning: Don't use it anymore! The best condition for an IACV is clean and dry. WD40 leaves residue that attracts contamination and causes repeat issues. After ultrasonic cleaning, you shouldn’t need any lubrication. If you need to run something through while still installed, use throttle body/intake cleaner since it evaporates without residue. I considered silicone spray after cleaning myself, but was convinced otherwise — “clean and dry” is the way to go. Regarding Solenoids: I’ve pulled 5 IACVs (both Z32 and J30) from junkyards, and every AAC and FICD solenoid has worked fine on a 12V bench test. This tells me solenoid failure is rare, and most IACV issues come from dirty housings or connectors — not dead solenoids. That said, I absolutely love getting rid of the old wire clip connectors, so the newer VG33 solenoids are a worthwhile upgrade for me.
 If you did want to upgrade your IACV Solenoids, here are the options for the VG33 part. There could be other compatible parts out there as well. -New OEM VG33 IACV from Japan (~$135 + $25 shipping, but beware of tariffs — I was charged ~$90 from UPS, currently working to get it corrected). -New OEM VG33 IACV in the US (~$250–$350). -Used OEM VG33 IACV from eBay. -New aftermarket VG33 IACV from Amazon (~$70, likely Chinese-made). -A great option for those that enjoy the Junkyard: Pull the plenum on a VG33 Pathfinder/Frontier and harvest solenoids + connectors in one go. Wiring Specialties Harness-Side Connectors:
AAC: La-Z-Link https://www.wiringspecialties.com/conc.html
FICD (same as VTC/Det sensor): La-Z-Link https://www.wiringspecialties.com/vg30-knock-sensor-connector-harness-side/ Ultrasonic Cleaner Recommendation:
Any decent 2L–3L unit with good reviews on Amazon will work. Smaller ones tend to have less wattage, which matters. I use a 3L, 120W model, but I also have a 1L model for smaller more fragile stuff. One last tip, your throttle bodies being balanced is necessary for a correctly setup idle! I had an additional unrelated issue to the IACV that screwing in my idle screw all the way wasn't bringing idle RPM down passed 900 or so. Once my TBs were re-balanced, the idle responded correctly to the screw and I could stall the car with it if I wanted to.
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IACV Ultrasonic Cleaning and VG33 Solenoid Upgrade - 
