Off Idle Issue

[Blwnmstgt1990]

Morning everyone, been lurking around here long enough so I finally joined. I've got a 90 GT that I built and trying to iron out an idle and off idle issue and want some input from everyone. Car is a 347 give or take with 8.5:1 comp, Vortech YSI, 95# injectors with matched Pro-M maf running off a series 4 PMS from AFM, 90MM TB with Foxlake matched Systemax intake and TFS heads with larger valves. EGR is gone and so is evap system (car ran fine with no tune on previous set up with a 302 and S-trim with 30# inj). Has a full msd set up with dizzy and associated items , timing is at 12* btdc and fuel at 44# just to give basics. I can get car to idle well (minor surging) but when I put it in gear and let off the clutch the car wants to buck and die. I went back and did the TPS adjustment and replaced the cleaned the IAC (then replaced it) with no help. Put the car on 30# injectors and stock ecu with matched maf and does the same thing. So any ideas on what it might be or where to start? Codes show for EGR and Evap system but nothing else.

 

[jrichker]

You guys with idle/stall problems could save a lot of time chasing your tails if you would go through the Surging Idle Checklist. Over 50 different people contributed information to it. The first two posts have all the fixes, and steps through the how to find and fix your idle problems without spending a lot of time and money. I continue to update it as more people post fixes or ask questions. You can post questions to that sticky and have your name and idle problem recognized. The guys with original problems and fixes get their posts added to the main fix.

It's free, I don't get anything for the use of it except knowing I helped a fellow Mustang enthusiast with his car. At last check, it had more than 159,000 hits, which indicates it does help fix idle problems quickly and inexpensively.

 

[Blwnmstgt1990]

Appreciate the response and the list, I had been using it to iron out the cause of the surge at idle. I'm not spending any money on parts when I (like most of us) have enough parts in my garage that I could build another two mustangs. When I say surge I'm only seeing 50 or so rpm surge. I am continuing to work that issue, however I am more adamant about finding the issue with it dying when I try to move it.