New to tuning help fix hanging idle

[Cstone812]

New to tuning. Car was already tuned for the cam and injectors. Ms3 cam, ported 5.3 heads, fast 102/102, speed density, 36/lb injectors. Idles at around 900 but when gas is pressed it likes to hang up around 1500-2000 and slowly drop down. Can anyone get me started somewhere? Thanks.

[mowton]

First order of business is to let the PCM know you have installed a 102mm TB in place of the stock 78mm. Go to the IAC steps vs effective area table. You can see the steps start at the 12 mm2 axis which is what the throttle opening crescent yields at closed throttle in the stock setup, then the iac steps impart their additional air by opening the IAC pintle more and more. So we will start by shifting that table from the 12mm2 axis up to the 22mm2 axis and set the 12 to 20 cells to 0. While not related, but just to keep everything inline, put the ETC scalar back to .0180 as well.

Now we are going to set up the scanner. Develop a .cfg that utilizes the following PIDS: IAC desired, IAC pos, LTIT PN/AcOff, LTIT Gear/AcOff, Idle Adapt (STIT), Idle Desired Airflow, Idle startup, Commanded AFR, RPM, ECT, MAP, Advance, Throttle Position %, Throttle position (V) and Dynamic Air.

Set up a separate .cfg with Idle desired, Dynamic air and IAC pos. We will use that later to fine tune the effective area table.

Next, we are going to get her started and dial in the IAC at operating temperature. If you haven't already, remove the setscrew from the bottom of the TB and re-install from the top...this will allow easy access for later adjustments. With the .cfg above, and at operating temp, adjust the setscrew so the IAC desired is between 50 and 80 steps and TPS volts is <.8v. When complete, turn engine off, unplug TPS and IAC. turn key on (don't start) for 20 seconds, shut off and reconnect connectors. This will complete the relearn process for the pcm and set 0% TPS as closed throttle. Let engine cool down and repeat if needed.

The last step is to log the LT and STIT from a cold start to high temp and update the BRAF based on these results. It is better known as the RussK cfg...

You do want to make sure that before you start tuning the idle/startup, that the VE and MAF are dialed in pretty good. From say 1200 rpm to say 800 use the pedal in neutral. Also as you get closer to the end, I like to shut off the idle spark control (over/underspeed) and make sure the air adjustments are the best they can be standalone. Then turning this adaptive feature back on makes it all that much better. Use the VCM controls to accomplish this.

Ed M