Idle issue after 90 to 102 throttle

[wesam]

Recently i changed the intake manifold with throttle from 90 to 102
I changed B4349 according to TBresizing spread sheet and adjusted the TB stop bolt so the TPS will read 0% at idle and 100% at WOT then start then adjust b4504 to 4.3 sec instead of 1.3 as read in one of threads
(my car my desired idle speed is 1000 rpm)
Well started the car with IAC steps logging
it start at nearly 2000 rpm then drops to 1300 and the IAC steps keep going down to 0 steps
Decreased the idle spark from 25 degree to 11 then it idled @ needed speed but i think 11 is too much low
what I'm doing wrong ?

attached log with the tune fileLog_0179.efi102.tun

[redhardsupra]

did you redo your Desired Airflow?

[wesam]

How could i redo it ?
i just tried to reduce the desired air flow but seams to do nothing because the IAC is reading zero steps

[redhardsupra]

map out your STITs over Desired Airflow table like axis, apply the delta to the base Desired Airflow

[wesam]

Sorry for the dumb question what is STIT ?

[redhardsupra]

Short Term Idle Trim. and if you haven't used them, then you're definitely not done doing your idle

[wesam]

Ok complete your favor and guide me how to do it please

[redhardsupra]

1. Log STIT, ECT, DYNAIR/VEAIR/MAFFLOW (depending whether you're using hybrid/SD/MAF).
2. Make a histogram that uses ECT as the x-axis, in the same intervals as your Desired Airflow table (they differ by year/model so no, so you gotta look it up first).
2b. for bonus points, filter throttle appropriate for your platform, so you catch idle only.
3. Start the car from cold, let it idle till full warm. I like to turn off the fans so the airflow isn't disturbed, and you get get higher on ECT without cooling it.
That will give you one set of data. If you have an automatic, than you'll have to wait till it's cold again, and run it again, this time in D (with your foot on the brake). Then rinse/repeat another two combos when combined with AC. But if you got a manual trans without AC, then one run is all you need.
4. Add the averaged STIT data grouped by ECT intervals to the respective Running Airflow table (depending on whether it was manual/auto and with/without AC).
5. Repeat until the STIT's converge upon a small number. Small cam cars can be tuned to under 0.1g/sec, bigger cams are a bit more unruly, but still the STIT averages should be small.

Usual mistakes:
a) The intervals of your histogram are different than of the Desired Idle
b) The units of the histogram are different than of the Desired Idle
c) The car wasn't fully cold, so you get only few cells of data.
d) The TPS sensor wasn't reset BEFORE you start the process.
e) Logging wrong throttle PID (technically not involved in the process, but useful to have)
f) The throttle body was in any way molested by porting/polishing/etc by a non professional. This one is subtle; in most cases it's not going to completely prevent you from doing idle correctly, but it will never converge on a stable set of settings either. Every damn tree-shade mechanic tries it and swears it's perfect, until they put in a stocker and everything gets instantly better.
g) Any other mechanical issues. leaks around the TB/intake tract obviously are going to screw with you. If you log the car enough times, you'll learn what is normal and what is abnormal.

[wesam]

Thanks for this answer
I did not find those two pids STIT,VEAIR
I'm running OLSD so i think no need for MAFFLOW is this correct ?

[joecar]

More info (you will find the rest of the answers here):

Idle Tuning
showthread.php?4661-Idle-Tuning-Helpful-Info-Inside
showthread.php?14439-Idle-Tips-amp-Tricks
showthread.php?14153-scan-tool-wont-log-rafig-or-rafpn
showthread.php?14435-Need-help-Can-Start-Car-but-dies-when-I-give-it-any-throttle-before-going-to-CL
showthread.php?7011-ETC-cars-and-IAC-parameters
showthread.php?14544-Working-on-my-idle-tune
showthread.php?14794-Help-with-open-loop-%28cold-start%29-tuning
showthread.php?149-Idle-%28Transition%29-Tuning

More Idle Tuning
showthread.php?t=149
showthread.php?t=5866
showthread.php?p=86553 post #17
showthread.php?t=2630
showthread.php?t=473

Throttle Cracker/Follower
showthread.php?t=3568
showthread.php?t=4081
showthread.php?t=5406
showthread.php?t=5940