89 5.0 Idle Issues

Discussion in 'Fox 5.0 Mustang Tech' started by Erick30150, Mar 20, 2017.

  1. alright so my fox has an issue with its idle on a cold start it'll jump up to atleast 1500-2000 Roma almost stall out but idles prettt normal after driving for an hour or stopped at a red light the cars rpm will drop about 150 Rpms and start idleing roughky but won't stall out accelerates poorly but drives perfectly fine I checked for vacuum leaks and nothing at all. I did pull some codes and swapped out the sensors that had the codes go off but CEL remains on and rough idle is still there I'll post the codes later as I don't have them atm
  2. With the CEL on, I guess we will start by saying you'll need to post the Engine off, and engine running codes
  3. 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. It includes how to dump the computer codes quickly and simply as one of the first steps. 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. :D

    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 200,000 hits, which indicates it does help fix idle problems quickly and inexpensively.
    jrp27540, 5.0Droptop and karthief like this.
  4. The codes are KOEO 31,41,66,95
    KOER 12,41,91,31 i already swapped out mass air sensor and egr valve as well as egr valve and as I stated before I checked for leaks I have no issues there as well
  5. What year is your car? Engine/trans? Original or swapped? Mass air conversion?
  6. 89 original 5.0 just pretty much stock everything beside the tb 70 mm and cai the maf is by pro.Mracing