Doesnt Run Consistent

Discussion in 'Fox 5.0 Mustang Tech' started by Tims97pony, May 11, 2013.

  1. i just traded for a 1990 gt. car required a healthy dose of ether to start initially. once started it would not idle until i turned the idle screw a bit but still ran rough. as it warmed up it seemed to run a bit better but was still very rough and missing quite a bit. although it has moments of wanting to come alive and run. it almost acts like it has bad gas in it, but i dont smell the normal bad gas odor. once warmed up i drove it the 7 miles to my house and even played around a bit and even did a small burnout on the highway in front of my house. turned it off and restarted it 4 or 5 times while warm without any starting problem, although it continued to have a rough idle and an intermittent miss. the following day i decided to check into it a bit more and started by trying to start it. i could only get it to hit here and there without it ever starting even with ether. the cap and rotor are worn but nothing that should cause this problem, the yellow coil appears to be aftermarket but has been in the car awhile. removed the #5 spark plug to find the plug itself covered in a light black layer. with exception of the electrode having a dull shiney spot. the plug did smell like fresh gas.

    the only mods that it appears to have are an open air filter, headers, no cats, dual flowmasters and h-pipe.

    i do realize that i still have a few troubleshooting steps to finish, but i thought id throw this out and see what opinions i could get from those with more experience on these cars than me.
  2. How long has it been sitting before you bought it and tried to crank it? If it had been sitting for along time you may want to clean the injectors,drain and clean the tank, change the fuel filter and give it a tune up.
  3. You guys with idle 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 you 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. :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 125,000 hits, which indicates it does help fix idle problems quickly and inexpensively.