Bad IACV?

[red coupe89]

so this off season i decided to do some work after having a bad injector. replaced all injectors with a new 800cc set, along with JWT mild cams. have finally gotten it all back together. started it up, little lifter tick to begin with but ran fine. set base timing at 15 BTDC all was well. next begin to adjust idle as it was sitting at about 1100 rpm. unpluged the iacv and began adjustments, go to plug it back in when idle is set and the car has not been right since. my a/f ratio is running dead rich at 9.0 and even with nistune i cant seem to get it back to stoch or even idle correctly. i thought maybe i had an injector hung open but tests show they are all operating correctly. pressurized the system for vacuum leaks to no avail. im just wondering if anyone has run into an issue with the IACV and some of these symptoms. thanks fellas.

[z.Leinbach]

Have to tske the car in to have a tune. Then again our cars run rich by nature. Possible the injectors are to big.

[red coupe89]

thanks, i can adjust injector size threw nistune which has worked well in the past. has anyone ever had an issue with there VTC actuators not advancing the timing properly? i dont know where else to look, getting to the point where im going to start tear down......

[z.Leinbach]

I can say through research. The vtc is only supposed to be advancing from about 1500 rpms to 5500rpms to improve torques. At idle and above 5500 its supposed to be a dead 0. So i think you iacv is good. But maybe idle tune needs adjusting

[red coupe89]

I can say through research. The vtc is only supposed to be advancing from about 1500 rpms to 5500rpms to improve torques. At idle and above 5500 its supposed to be a dead 0. So i think you iacv is good. But maybe idle tune needs adjusting

thanks, im going to snap a video later to try to elaborate on the issue. hoping i can get this squared away and dont have to start tearing it apart at the beginning of the season

[z.Leinbach]

No worries man. An i feel ya. I have to take my front end apart again already

[red coupe89]

https://youtu.be/Lhm6yvIeSkk

https://youtu.be/i9j4cKEcoZU

Took these two tonight. I think I may have another lead on the issue. Not sure if anyone here does a thing called indexing there spark plugs. I have done so and think this may be fouling the plugs out. Tomorrow we'll find out.

Thanks!!!!

[DCaff300ZX]

OK, the videos did help as I now agree that maybe it isn't the IACV...but wouldn't bet completely against it as the IACV is a finicky beast and well-known for idle issues in a variety of ways.
If it was the IACV causing the issue I saw, I'd say from the steady rpm drop to almost dying it acts more like bad initial setup with the IACV unplugged (too low setting), or a vacuum/boost leak than anything else so I'd do a re-set of the base idle, and then a hose check in the IACV area looking for something that isn't obvious- once I found a leak in the hose that connects the balance tube that was on the bottom of it and not very evident, probably only tore enough to find that one last time I took it off and I only looked there in desperation after hours of work elsewhere to no avail obviously.
I also assume you replaced the connectors, and at least made sure you have NO corrosion there and elsewhere such as the PTU harness? Corrosion of the connectors and harnesses causes a variety of odd idle issues as well, I've had most of them before replacing pretty much every damn connector and sensor in the front of the car, and went to a new IACV after a used one also had the same general problems my old one did. Buy new only.
Hope this helps!

[red coupe89]

OK, the videos did help as I now agree that maybe it isn't the IACV...but wouldn't bet completely against it as the IACV is a finicky beast and well-known for idle issues in a variety of ways.
If it was the IACV causing the issue I saw, I'd say from the steady rpm drop to almost dying it acts more like bad initial setup with the IACV unplugged (too low setting), or a vacuum/boost leak than anything else so I'd do a re-set of the base idle, and then a hose check in the IACV area looking for something that isn't obvious- once I found a leak in the hose that connects the balance tube that was on the bottom of it and not very evident, probably only tore enough to find that one last time I took it off and I only looked there in desperation after hours of work elsewhere to no avail obviously.
I also assume you replaced the connectors, and at least made sure you have NO corrosion there and elsewhere such as the PTU harness? Corrosion of the connectors and harnesses causes a variety of odd idle issues as well, I've had most of them before replacing pretty much every damn connector and sensor in the front of the car, and went to a new IACV after a used one also had the same general problems my old one did. Buy new only.
Hope this helps!

thanks dcaff, i have checked all the hoses too which i did find some leaks. i have squared them all up and re-pressureized with positive results. i have also gone over all the hoses connected to the iacv with tb cleaner and did not get any change in idle. connectors have all been replaced/repaired . im beginning to question my injectors fouling out my plugs. when i have had said problems my a/f is at 9.0 and the car runs with like random misfire. my gap is set at .029 on new OEM plugs as im running 22psi of boost. im wondering if them being indexed isint drowning them in fuel. going to work on it tonight, will report back with progress/more videos.

THANKS!

[red coupe89]

So I decided to double back and start checking everything that has been touched/replaced. Got down to the spark plugs and my gap was off .005. They were covered in soot so I cleaned and re-gapped to .031 and now it is running alright. I am now in search of a vacuum leak it seems like aaaaaaaahhhhhhhh