Idle (Transition) Tuning

[jfpilla]

Just wanted to add a couple of cents to this awesome thread.

Jfpilla spent a lot of time helping me out with this. I performed the procedure over and over and I was never able to get my IACDES_B to match DYNAIR. The car idles good (not great) and still bucked like a bronco under 2k RPM's.

A couple of days ago, P Mack on LS1Tech made a post in regards to modifying the IAC Effective Area (B4403) table. Link http://www.ls1tech.com/forums/showthread.php?t=309671. I performed these steps, in conjuntion with Jfpilla's write up, and in 30 minutes, my car idles like stock, except for the pleasant loping sound.

After you have performed the idle transition tuning, you will need to shift the cells in the B4403 table down until your IACDES_B matches DYNAIR.
On a stock Fbod, the 12mm^2 is the value that the IAC motor starts to step. After I was done, I had shifted the cells down to 28mm^2.

TA glad you've solved it. Bet you like your car again. I read the thread you mention. It does sound like a good additional step to tuning.

[TAQuickness]

TA glad you've solved it. Bet you like your car again. I read the thread you mention. It does sound like a good additional step to tuning.

You'd win that bet

[jfpilla]

TA glad you've solved it. Bet you like your car again. I read the thread you mention. It does sound like a good additional step to tuning.

You'd win that bet

TA thanks for the information. A number of good tuners have tried this and had good results. I made a change to the tuning instructions.

[bink]

Joe - Finally got my car back on the road! Moved the IAC Eff Area down 6 places (14 mm sq -> 26 mm sq). Runs great. Idles very well. DFCO is back to stock. I actually cruised in 6th gear at 1500 - 1600 rpm.

Thanks for the Help!
Have a safe and happy 4th (hope you and yours are boating)!!

Cheers,
joel

[jfpilla]

Joel,
Glad it works for you. So far it has for everyone I know that's tried it.
I can't wait to try this new stuff. ie: effective area, autotune. With the downtime, I had my WB tuned up, so that should help. I've been promised my car by monday. Now I'm anxious.
Joe

[Z16DNA]

Advise please. I believe I've followed the instuctions above for Idle Transition Tuning, but when I adjust IAP to match my DESIAC and MAF result is always a .5 differance with IAT at 53C. I've tried adjusting IAP for 60C and 40C range. Large movements in either direction, no change. Differance between DESIAC and MAF map values at ECT 92C remain the same. I've got to be missing something - easy...

Kevin

[TAQuickness]

Z16 - are you running a large cam?

[Z16DNA]

Slightly above average size. Comp Cams 228/232 114 +4 Plan to install SC in future - do you hear me Mrs. Santa Clause?

[TAQuickness]

You may need to move your IAC Effective area table down a bit. That was the only way I could get my numbers corresond.

[bink]

I had a nagging, persistent problem with Idle. 2001 Vette. 239/251 cam. 90 mm TB, Fast intake and headers.
The electronic throttle idle would periodically learn downward 4-5 g/sec and 4-5 % TPS. It would drop the TPS from 11-13% to 6-7% and Desired airflow from 11-12 g/sec to 6-7g/sec. It was driving me nuts!!

Added air for the fans -B4301, B4302 (.75/1.50 g/sec).

Added air to the "Idle Learn AC Limit High Table"- B4326 (4.00 g/sec)

I had already increased my "Idle Learn Drive Limit High"- B4324 (3.00 g/sec).

Problem is cured!!
FWIW.