Car idles very rough and shuts off?

Discussion in 'Fox 5.0 Mustang Tech' started by blackcobra, Dec 12, 2003.

  1. The check engine light would turn on every time I would punch the accelerator and turn off as I soon I let off the gas.The car still ran fine untill last night when It began to hesitate and turn off, my exhaust tone was much louder and different. Right now the car turns on and the check engine light is always on now. The car surges and when i press the gas the RPM needle takes awhile to com back down to idle. The smell of gas seems stronger, I made an appointment for tuesday to pull codes unless I figure out the problem myself and you guys. The car would also sometimes not accelerate when I pressed the gas the it would shut off? Help
  2. Sorry forgot mods.
  3. FUEL PUMP!!!!!!!! I am going to say this is your problem. I had the SAME EXACT problem and came to find only 9psi of fuel going to my rails. Replaced it with a 255lph intank. Fixed.
    Let us know what your cure is!

  4. also cleaning out the throtle body and all those hoses in the intake and stuff around there would help a lot witht he idle.
  5. Is it overheating too? If you have a reliable gauge, I'd double check that. A bad fuel pump will cause the temps to climb and eventually shut off when the EEC pulls timing.
  6. No the tempature was fine ita was at 190* give or take. Thanks for the replys, is there a way to test my fuel pump to see if its bad? thanks
  7. A shop had an opening today so I dropped off the car. They called me and told me that my computer wasnt sending and signals to my mass air. He said the mass air has power but the computer is not reading the signals. He said to replace the computer with a used one from a junkyard. Does his info semm about right?
  8. WTF, now the car is running fine I havent done anything to the car and all of the sudden its cured. The mechanic said the same problem may occur in the future if the computer is the problem.
  9. I have a '92 LX 5.0 and I have that exact same problem... if you replace the computer and it fixes it, post up on here again, because it would be nice to not have to rev my engine up every time i want to go anywhere. I mean it turns heads, but if it stalls out, you know, its a little embarassing. By the way, your mechanic was right when he told you it would come back, its been coming and going on me for about a year now.
  10. I'll be swapping the computer on Monday, l'll keep you updated.
  11. I have seen this problem. Does the prob seem to be related to moisture? Humid air? Try unplugging the MAF if the car acts up. If the car runs much better, then there is a good bet the puter or the MAF is bad. And if the shop says it tested bad, it may very well test good now. All you need is a low impeadence ohm meter to test it and the Probst book. Its not that big of a deal to check one out, you just have to take your time and follow the instructions, letter by letter, thats what is hard for me sometimes.
  12. Check your EGR valve. The symptoms you describe might be caused by this. Worth checking out. :nice: Good Luck!