got 88 fox body 5.0...It wont idle.if I go balls to wall she runs fine but when u let off seems like its overloading an stalls,fires right back up but wont idle almost..pls help!!!!!
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.
well bought code reader its not showing any codes..When its hot outside it runs fine,idles a little high,but early morn starts it will not idle seems like its over loading an stalls,if i run it hard it goes fine but as soon as i let off gas it over loads an stalls..(Thats if its in early morn..plz help
got 88 mustang,if its hot outside it runs just fine,try to start early morn it just seems like its over loading an stalls,if i run it hard it runs just fine unless i let off gas then it over loads an stalls..(when try early morn starts)
well bought code reader its not showing any codes..When its hot outside it runs fine,idles a little high,but early morn starts it will not idle seems like its over loading an stalls,if i run it hard it goes fine but as soon as i let off gas it over loads an stalls..(Thats if its in early morn..plz help
Just drill, did you use the surging idle checklist to show you how to dump codes? If you followed those instructions, and cautions, you did it the correct way.
Aft reassuring yourself and us that you did it the correct way and don't get at least an 11, all OK, then do the next step.
Computer will not go into diagnostic mode on 86-90 models 5.0 Mustangs
Disconnect the battery positive terminal before making any resistance checks.
The voltage drop in the ground cable will cause incorrect resistance readings.
How it is supposed to work:
The black/white wire (pin 46) is signal ground for the computer. It provides a dedicated ground for the EGR, Baro, ACT, ECT, & TPS sensors as well as the ground to put the computer into self test mode. If this ground is bad, none of the sensors mentioned will work properly. That will severely affect the car's performance. You will have hard starting, low power and drivability problems. Since it is a dedicated ground, it passes through the computer on its way to the computer main power ground that terminates at the battery pigtail ground. It should read less than 1.5 ohms when measured from any place on the engine harness with the battery pigtail ground as the other reference point for the ohmmeter probe.
What sometimes happens is that the test connector black/white wire gets jumpered to power which either burns up the wiring or burns the trace off the pc board inside the computer. That trace connects pins 46 to pins 40 & 60.
The STI (Self Test Input) is jumpered to ground to put the computer into test mode. Jumpering it to power can produce unknown results, including damage to the computer. The ohm test simply verifies that there are no breaks in the wiring between the test connector and the computer input.
How to test the wiring:
With the power off, measure the resistance between the computer test ground (black/white wire) on the self test connector and battery ground. You should see less than 1.5 ohms.
If that check fails, remove the passenger side kick panel and disconnect the computer connector. There is a 10 MM bolt that holds it in place. Measure the resistance between the black/white wire and pin 46 on the computer wiring connector: it should be less than 1.5 ohms. More than 1.5 ohms is a wiring problem. If it reads 1.5 ohms or less, then the computer is suspect. On the computer, measure the resistance between pin 46 and pins 40 & 60: it should be less than 1.5 ohms. More than that and the computer’s internal ground has failed, and the computer needs to be repaired or replaced.
If the first ground check was good, there are other wires to check. Measure the resistance between the STI computer self test connector (red/white wire) and pin 48 on the computer main connector: it should be less than 1.5 ohms. More than 1.5 ohms is a wiring problem
The following is a view from the computer side of the computer wiring connector: it is for an A9L, A9P computer.
Diagram courtesy of Tmoss & Stang&2birds
Check out the diagram and notice all the places the black/white wire goes. Almost every sensor on the engine except the MAF is connected to it.
got 88 fox body 5.0...It wont idle.if I go balls to wall she runs fine but when u let off seems like its overloading an stalls,fires right back up but wont idle almost..pls help!!!!!