2G rich idle issue

[la-panocha]

I have been working on fixing rich idle condition for a while.
I have ruled out vacuum and boost leaks.
I just replaced IAC.
Throttle body is clean.
Compression warm is 155 across all four cylinders.
New plugs/wires.
Car runs great when not in idle but idles about 850-900 in park but idles really low when at stop in D. The ST FTRM in idle is about -3 and LT FTRM is +12.5

Lets say you had TB out and all sensors off and replaced shaft seals and gaskets BISS o-ring etc. What steps would one take to get IAC/BISS dialed in? I have TPS reading about 0-.4%(fluctuates but mainly at 0%)

I have tried finding out about what hood placard says about grounding something and setting idle at 750 +/- 100 rpms but nothing is real definitive. Any links to a step by step procedure would be greatly appreciated!!
Thanks in advance

 

[92AWDHX40]

Terry's Talon Troubleshooting Tips #3 - Fast Idle (aka. Idle Surge)

 

[rb26alpha]

Well your profile dosnt say much on what mods you have done if any at all, so i would double check what youve done, check the pvc lines make sure not clogged up add a oil catch. You look like you know what your doing but with a turbio car it could be the smallest thing. There is a screw on the throttle to control idle but im sure you already know that. Good luck

 

[la-panocha]

Thanks for link IUGRAD.

Here is basic timeline since I got car.
(trans was in limp-in mode, fixed by replacing fuse)
First thing I did without any mods done of any kind and just got car from original owner....boost leak test. She had more leaks than the titanic
Replaced leaky spots....BISS o-ring, injector seals, int mani gasket, TB shaft seals and gaskets, 2gen BOV(died at the business end of shotgun) 1Gen BOV, disconnected valve cover line to pre-turbo inlet to eliminate oil vapor in system, ran hose from turbo straight to WG actuator ( bad WGA solenoid/stuck open)
Boost leak test = no leaks.
Replaced plugs with 1 step colder plugs gapped at .028 without boost stutter and new wires.
CEL...bad FPR solenoid...replaced with OEM. FPR works like new with NO gas in vac lines.
Replaced battery, and then had issue with alternator voltage regulator, replaced all battery ground wires and put in new alternator.

Turbo check showed lots of shaft play and 4" crack on bottom of exh manifold.
This forced me to get new turbo and manifold and decided to play it safe and get the EvoIII16G
After install did boost leak test and minor leak at J-pipe....fixed.
All this time and idle condition was somewhat poor but driveability was fine.
CEL for bad upstream O2 sensor, replaced with new bosch sensor.
Replaced fuel filter.
Pulled IAC and did ohm check to find only 1 set had proper ohms.
Got new IAC and tested ohms immediately and all are good between pins
Connected harness to IAC and cycled key and IAC functioned properly.
Put IAC in, checked everything out visually, of course did another boost leak check and holds 14psi.
She fired right up and idled at about 1600 and then dropped to 1000rpm when warm. Adjusted BISSS to try and get idle to about 800rpm, with BISS bottomed out she idles at roughly 750rpm. Took for test drive but when put into gear(auto trans) she idled down to about 450ish and wanted to die. Drove back streets for about 1 mile at 25mph and then got to open her up and she runs great jumping from 45mph to 70mph in a blink of an eye, nice n smooth, boosting at roughly 15psi max.
Still have low/rough idle and scanner shows previously said FTRMS.

The only thing I haven't figured out is why one of the solenoids on FW connected to TB/evap will tick tick tick rapidly and then stop, start, stop but tests show solenoids are working properly.
I read thru link that iugrad92turbo had posted for me(thank you and nice read btw) and as good as it was it did not help me out.

I have checked all wiring harnesses, fuses, and I am still at a complete loss for why there is problem with just the base idle.
If anyone has anymore ideas no matter how trivial it might be even asking me if I checked blinker fluid and muffler bearings....

Is there ANY possibility that the coolant temp sensor is faulty and ECU is thrown off by that and if so could I rule that possibility out if my actron scanner shows coolant temp at 190ish when warmed up? Dash gauge reads properly(for whatever that is worth)

 

[007jimmy]

2G BISS Adjustment

 

[la-panocha]

2G BISS Adjustment

BINGO just what I was looking for! THANKS 007 I will go thru that when time permits and report back.

 

[la-panocha]

Been a while but here is what I have done....
Started with removing TB and checking FIAV passage, cleaned a little bit out but really was cleaner than expected.
Found a 97 spyder at junkyard 2 days after it was dropped off and vultures had already stripped interior, TB, turbo+mani, inj/fuel rail....anyways... I did get clean EGR valve and all four brake calipers and mounting brackets with brand new pads for $13 a piece.(I sandblasted them, cleaned and painted them, just waiting for time to install)
Put other EGR valve in, put TB back in, boost leak check.
Reset the factory dead stop and did steps per 007jimmy's link.
Fired right up and idle only had one issue, high rev at start and slowly dropped down to 900 rpm's. FIAV is bad. As I watched the LTFTRM % it went from 12.5 down to about 6.8 then fluctuated a little bit. The ST FTRM was still around -3.8 to 1.5
When warmed up the idle is smoother than before but still feels like very faint missing. ? I think regapping plugs to factory and then adjusting them down again till no boost stutter. (running BPR7ES)

I will mill out a FIAV blockoff plate and probably same for EGR. I suspect old EGR was letting in too much exhaust causing poor combustion.