[rfmaster]

Originally Posted by philthethrillohio

its a 87 305 tbi. when i quoted the guy and said i have the same truck figured that make it clear but anyway.i replaced all the sensors so i know where they are. i guess my ne w question is if you replace the iac do you need to resetthe ecm computer? i put one in and went to adjust min idle and it was idling so high, took idle screw so it wasnt even touchingand still high idle. ive heard when replacing you need to disconnect batery for 10min or so to reset ecm or you will have idle around 1500. anyone heard this?

OK - I see what you have. Yes, when ever replacing IAC you need to reset IAC by jumping pins A&B on ALDL connector (inside cab), disconnecting IAC connector and shutting engine down - see full IAC procedure (use search). If IAC was correctly reset resetting ECM is not required, although it does not hurt to do it - it clears all flags, BLM's, etc.

10 minutes with bat cable off is a bit excessive - all it takes about 10 to 30 sec for ECM to loose its memory when battery cable is removed.

high idle speed can be due to a vacuum leak - these usually form between intake and TB especially if that gasket was never replaced. Another reason for high idle is incorrectly set base timing - which must be set EST connector open engine idling around 625 RPM or less. This when you can adjust minimum idle screw.

//RF