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 file1070010701

[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 (http://forum.efilive.com/showthread.php?4661-Idle-Tuning-Helpful-Info-Inside)
showthread.php?14439-Idle-Tips-amp-Tricks (http://forum.efilive.com/showthread.php?14439-Idle-Tips-amp-Tricks)
showthread.php?14153-scan-tool-wont-log-rafig-or-rafpn (http://forum.efilive.com/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 (http://forum.efilive.com/showthread.php?14435-Need-help-Can-Start-Car-but-dies-when-I-give-it-any-throttle-before-going-to-CL&p=129519&viewfull=1#post129519)
showthread.php?7011-ETC-cars-and-IAC-parameters (http://forum.efilive.com/showthread.php?7011-ETC-cars-and-IAC-parameters&p=61455&viewfull=1#post61455)
showthread.php?14544-Working-on-my-idle-tune (http://forum.efilive.com/showthread.php?14544-Working-on-my-idle-tune)
showthread.php?14794-Help-with-open-loop-%28cold-start%29-tuning (http://forum.efilive.com/showthread.php?14794-Help-with-open-loop-%28cold-start%29-tuning&p=133446#post133446)
showthread.php?149-Idle-%28Transition%29-Tuning (http://forum.efilive.com/showthread.php?149-Idle-%28Transition%29-Tuning)

More Idle Tuning
showthread.php?t=149 (http://forum.efilive.com/showthread.php?t=149)
showthread.php?t=5866 (http://forum.efilive.com/showthread.php?t=5866&highlight=RAFIG)
showthread.php?p=86553 (http://forum.efilive.com/showthread.php?p=86553) post #17
showthread.php?t=2630 (http://forum.efilive.com/showthread.php?t=2630)
showthread.php?t=473 (http://forum.efilive.com/showthread.php?t=473)

Throttle Cracker/Follower
showthread.php?t=3568 (http://forum.efilive.com/showthread.php?t=3568)
showthread.php?t=4081 (http://forum.efilive.com/showthread.php?t=4081)
showthread.php?t=5406 (http://forum.efilive.com/showthread.php?t=5406)
showthread.php?t=5940 (http://forum.efilive.com/showthread.php?t=5940)

[wesam]

thanks Joe i already checked those threads

[joecar]

If no MAF, then try GM.DYNAIR or GM.DYNAIR_DMA.

[wesam]

I have hard time now i could not set the stop bolt to the right position
if i tight it so the car will idle at the desired speed it will hang and some times because it seems closed more than it should be so the blade will touch the throttle and i have to press the pedal hard to release it
if i open it a little so it will not hang the car will idle at 1500 rpm
I tried to tight it until the TPS voltage will be in the least allowed voltage 0.4v with out luck ( it will hang some times when i press the throttle pedal )
I don't know if its a mechanical problem or a tune problem but i don't think so because its a brand new throttle

[wesam]

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.

Ok now i made the histogram you told me about but i didn't got your point number 4 so please explain it to me
here is what i find :
I'm commanding nearly 5 g/s in the desired airflow table B4307 but when i log the car it shown that DYNAIR is reading nearly 12.5 g/s ( throttle blade closed as much as possible to retain desired idle speed )
what should i do ?
I will log IAC_STD_DMA today if this will help

[wesam]

Any body ??

[joecar]

Ok now i made the histogram you told me about but i didn't got your point number 4 so please explain it to me
...wesam,

try this, look at post #4: showthread.php?5866-Auto-VE-questions (http://forum.efilive.com/showthread.php?5866-Auto-VE-questions)

[wesam]

Joe the problem I'm facing now that the IAC steps is zero when the throttle blade is closed as possible but the idle still little high so if log the STIT/LTFT and try to decrease the desired airflow table that will make no effect due to IAC is reading zero
at least this is my idea about the problem
any help will be appreciated

[joecar]

Two things I can think of:
- does throttle blade stop screw have any further travel available to it...?
- does throttle blade hole appear to have been enlarged...?

[wesam]

-Yes the throttle stop screw still has a lot of travel in both ways
- the throttle is brand new FAST 102 with out any hole

[wesam]

redhardsupra i hope you step back to help me please

[ChipsByAl]

The IAC counts cannot be left at Zero. Remove the duct in front of the Throttle body and turn the screw until the blade sticks in the bore. Turn the screw in some so the blade doesn't stick anymore. You will want to test the sticking again with the engine running, sometimes the vacuum will pull it to a sticking position again. If that happens, turn the screw in a little to avoid it. This will be the minimal position the blade can be at. If you move the screw, keep track of where you are in relationship to this position. Do what you need to do to get the engine running and warmed up. You may need to drive it to get the IAC to reset and the ECM will then know its counts/steps. When you stop and are in gear or neutral, the scan tool should show some counts. Make sure the TPS read 0%, you may need to dremel out the mounting holes of the TPS and break off the tang that locates it. Keep the TPS voltage low, your prior post about 0.4 volts is ok. There should be no TPS related codes setting DTC's.

One more thing, make sure your IAC is not malfunctioning!! If the wiring is broken, especially near the connector, you will get Zero IAC counts and the idle can be way high. That will be because of an IAC that doesn't move but the ECM/PCM thinks it is moving. Don't remove it and test it with the harness with the key on, you will likely ruin it. A good IAC noid light will identify an intermittent IAC wiring problem. You might want to use one first.
AL

[wesam]

I removed the duct in front of the TB before and adjusted the screw so the blade did not stick but when i did i had a high idle 1700rpm
and tried to decrease the desired airflow by 10% but the idle still at the same point which i think means that there is too much air getting in the intake also my TPS voltage was 0.6 at this point so i adjust the screw back so it will hang now and the idle is 1050 with TPS voltage 0.4 V

Also there is not MIL codes and when the car moving the IAC is reading just when its idling now i have zero steps

[ChipsByAl]

OK, you said "I removed the duct in front of the TB before and adjusted the screw so the blade did not stick but when i did i had a high idle 1700rpm
and tried to decrease the desired airflow by 10% but the idle still at the same point which i think means that there is too much air getting in the intake" I'm gathering you tried this once already. If the blade is almost to the point of being stuck in the bore, TPS voltage is ~.4-.6, if the idle is too high, you have too much air getting in the intake manifold. Now you need to find out where it is coming from. Go ahead and put the blade at the minimal opening, fire up the engine without the air duct there, then use your finger and seal off the IAC passage. If the idle comes way down or stalls, that is where you are getting the air from. If the PCM is showing Zero IAC counts when the engine is revving too high, and you seal it up and the RPM's come down, you have an IAC control issue. No amount of tuning is going to fix it.
Al

[wesam]

OK Al i tried today to close the IAC hole using my finger i felt there is a vacuum puled through the hole but the idle never goes down while I'm closing it i think that means there is a vacuum leak in the the throttle or the intake manifold but how could i know for sure ?
Any idea ?

[joecar]

Use brake cleaner to find leak (spray at intake manifold-to-head interface and see if it gets sucked in).

Can also use smoke like this (from inside manifold or from outside).

[ChipsByAl]

If the scan tool shows Zero IAC counts, there shouldn't be much vacuum at the IAC hole. Was the throttle blade near sticking in the bore? If it was and you sealed the IAC inlet passage, there is a vacuum leak. Check and plug the PCV and Power Brake booster hoses to start with, they are easy. After those, it gets a little tricky locating a leak.
Al