Engine Surging Idle after H/C/I

[johnny_261]

Hey Everyone,

To give you some background, I've just finished putting my engine back together after doing a H/C/I swap with Trick Flow 170, GT40 intake, and Comp Cams XE-264HR. The engine before was stock and ran perfectly fine. This would leave me to believe that the issues wouldn't be caused by any faulty sensors or hardware, but by something else...anyways the issues are as follows:

After finishing getting it fired up, it idles pretty decent when it is cold. However, when press on the gas to get the revs up and then let off, the idle bounces up and down before getting settled again. When the car gets warmed up the idle starts to surge and bounces up and down from 700rpms - 1500rpms and can stall out sometimes.

I tried to do the base idle reset, but when I got to the step where i disconnected the IAC, nothing happened. Is the idle suppose to change once I disconnect the IAC??? Also, the idle didn't seem to be affected much when I adjusted the idle set screw. What could this mean?

I'm still relatively new to these cars, so I need some ideas on where to start looking.

Thanks in advance for your help.

 

[88vert5oh]

http://www.stangnet.com/mustang-forums/threads/help-me-create-the-surging-idle-checklist.698148/

 

[gearheadboy]

You probably shouldn't have adjusted anything yet. Refer to the above checklist to set the throttle plate and TPS. If it is not perfect don't worry just yet. It takes some time for the computer to relearn. I kept fighting mine only to find that if you drove it a few times it straightened up. Anytime the battery is unhooked it will become confused.

 

[James.Little]

Yeah, sometimes I wish they would put in some non-volatile memory with a reset switch to erase what is stored. Oh well.