420A 2GNT IAC problems

[96WhiteEclipse]

Hey guys, so i have a 2g GS and this will be the 4th time replacing the IAC valve. My symptoms are a sputter at idle and on initial acceleration from stop or slow rolling. I figured it could be a fuel issue but I have ruled that out, replaced filter and pump, injectors are good. It’s also not an air issue as there’s a new filter. And plugs only have 8k miles on them. After getting new IAC car runs great but then the stutter begins again. I’ve gotten the durlast gold and regular brand. Any ideas? Connector is still water tight and seems to be okay. Although I fear it could be something else because after unplugging the IAC the sputter/quick cutout at idle still occurs. As well, there are random moments where the car will just stay in high idle. Any suggestions?

 

[dwb]

A boost leak test should be your first troubleshooting step. If that doesn't show any major post-throttle plate leaks, start looking into adjusting the BISS. Check the FSM for proper procedure. If still no joy, look at blocking off your FIAV. Might also be worth verifying your TPS is working and set correctly.
Have you replaced the plug wires recently? Do you have anyway to data log the car? How about the check engine light, is it illuminated all the time or just briefly after turning the ignition on?

 

[SixBolt_16G]

Had the car started to run correctly at any point when replacing the IAC 4 times?

Have you checked all of your vacuum hoses for leaks?

 

[97egl]

A boost leak test should be your first troubleshooting step. If that doesn't show any major post-throttle plate leaks, start looking into adjusting the BISS. Check the FSM for proper procedure. If still no joy, look at blocking off your FIAV. Might also be worth verifying your TPS is working and set correctly.
Have you replaced the plug wires recently? Do you have anyway to data log the car? How about the check engine light, is it illuminated all the time or just briefly after turning the ignition on?

Its a GS so would be the N/T 420a engine so no FIAV to worry about or BISS to adjust.

TPS is still a good thing to check as well as if there are any codes. EGR getting stuck can also cause symptoms described.

First thing Would be check for codes and vacuum leaks.

 

[96WhiteEclipse]

Its a GS so would be the N/T 420a engine so no FIAV to worry about or BISS to adjust.

TSP is still a good thing to check as well as if there are any codes. EGR getting stuck can also cause symptoms described. First thing Would be check for codes and vacuum leaks.

Hmm I’ll give it a try

 

[dwb]

Its a GS so would be the N/T 420a engine

Ah, you got me, I was thinking GST.

 

[BLACK'98DSM]

Sounds like a vacuum leak to me. No need for a 5th IAC valve. If you resolve the issue I would swap back to the OEM IAC. Or at least install the OEM tip on a new valve. All replacement valves are universal fit for Mopar engines, including 4 litre and even diesels. Which all require more air and have a smaller tip which can raise your idle or rev to high in neutral motion.