Engine Strange Knock/shake.

Discussion in 'SN95 4.6L Mustang Tech' started by Jarrod, Apr 3, 2014.

  1. Hey guys, first post. I've been having a little problem troubling me with my new '98 GT. She seems to be running a little hard or something. She has a slight vibration while idling in neutral. She also shakes a bit when I shut her off. Any ideas what could be wrong?

    Also... I know for sure she has been ran pretty hard by her past owner... Probably has something to do with it. Hopefully not, and it's something I can repair. Lol. Thanks guys.
  2. Does it sound like a miss? Any codes thrown?
  3. Sorry for such a late reply @COramprat , it's just enough for me to notice a feel. It sounds like it runs fine. It's throwing a few codes... I'll post them.

    Lack of HO2S21 switches - Indicates rich

    Evaporative Emission System Control Valve (Low/No flow)

    O2 Heater Circuit (Bank 2, Sensor 1)

    Lack of HO2S21 switches - Fuel Trim at Limit - Sensor indicates lean

    Catalyst system efficiency below threshold bank 1
  4. How long has it been since it's had a tune up? Plugs, wires, fuel filter, etc. Running a can or two of Seafoam through it might help some too if it's got a few miles on it.
  5. I haven't yet done a tune-up. I know I should have when I got it, just in case, but I'm skiddish after what happened with my F-150. I'll do one as soon as possible. See if it helps. And how do you run seafoam?
  6. Check Youtube. There are about a bazzilion video's out there how to do it. Enjoy the smoke show. :)
  7. 1st and foremost you have a bad catalytic converter. That would cause some of the vibration/rough issues you describe. Do you have emissions testing in your area? If not, go with an off road H or X pipe instead of replacing the cats. I think that would cause the lean and rich codes as well.
  8. Haha, okay, thanks @Gearbanger 101 I'll run the seafoam. Thanks to you too @COramprat . As long as I know the issue's not terribly tragic... I'll get a new system when I can. (Month or two) Also going to check my sensors too. Thanks guys. Appreciate it.
  9. I know... Late reply, but I have got the engine to stop jerking while in gear. It was the PCV and hose assymbly. It still does the knocking, but after getting my head out of my ass and asking a ASE-certified Ford mechanic, he said that there is no miss. He said it feels like there is something loose underneath and is hitting the frame. haven't checked it out yet though... One problem at a time. :p