Hey guys. So I have a rough idle and backfire/missfire at start up every single time. I start it runs like crap for like 2 minutes. Than the idle changes and smoother out than I take off and all is well. If I kill it even if warm it does it again. Any ideas? Thanks.
The computer runs in open loop for the first 2 minutes or so upon startup. It makes minimum use of the sensor data and runs on preset tables to calculate fuel mixture and spark advance. Once the engine warms up, it switches to closed loop and uses all the sensor data to calculate fuel mixture and spark advance.
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.
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 250,000 hits, which indicates it does help fix idle problems quickly and inexpensively.