2004 V6 Mystery Misfire

Discussion in '1996 - 2004 SN95 Mustang -General/Talk-' started by Jeffery Michael, May 28, 2014.

  1. I just bought a Mustang about a month ago. It drove great for about two weeks.

    The weekend of Mother's Day, I filled up the gas tank and went through a drive-thru carwash. 20 miles into the tank, the cars starts sputtering and bucking like the engine is going to jump out of it, complete with a flashing SES light. I had it towed home. Took it to the AAMCO down the street and had the code read, declining their $300 spark plug replacement. Code is P0302, misfire on cylinder 2. Also, when I returned home, I noticed a bit of water leaking off the muffler. It was maybe 1-2 cups of water.

    So, I next towed it to a local mechanic, who replaced the spark plug (which was relatively new) on that cylinder and the boot on the spark plug wire. He felt it made it run "sorta better". I came in and drove and could tell it was still bad before I got out of the parking lot. Sure enough, a quick drive around the block and the SES starts flashing again. Engine isn't bucking like it was when the misfire first started, but running really rough. Same mechanic tries replacing the wire, no result.

    Doing some of my own research at this point, I'm starting to suspect the coil pack. The previous owner had recently replaced it and it looks brand new. I have read of some people who doused their engines with water and damaged the coils causing the same problem.

    So, on to shop #2. This is a shop that specializes in head jobs. After having the car for a week, I get the call I've been waiting for. The car is fixed and ready to go! They replaced the fuel injector on that cylinder and it's running good as new. NOT. As soon as I start it up, I can tell it's not fixed, and again, driving less than a mile causes the misfire and blinking SES light again. The mechanic couldn't believe it, so he cleared the codes and we went out for a drive. Halfway around the block, misfire, blicking SES.

    So, I left it there and the owner of the shop says he called in a specialist with some special equipment to diagnose the problem. I get the call today that the car is again ready to pick up. What did the specialist do to fix the problem this time? He replaced the spark plug on cylinder 2. Are you ****ing kidding me?!

    So, I don't know what to do next. The owner of the shop wants to take the engine apart now, but that's obviously not going to be cheap, so I'm looking for anything else that could be causing this before I am out $1000+. I want to trust that the mechanics know what they are doing, but it really seems like they don't. Any advice you guys have would be awesome. Thanks for reading.

    New (maybe regretful) Mustang Owner
  2. Did they do a compression test? Sounds like they are throwing things in there and hoping for a fix instead of actually diagnosing the problem. While all of the things they replaced would have been in the steps to fix the issue they failed by not actually finding out what is wrong. Make then do a compression test 1st before they do anything else. Maybe @LaserSVT can help.
  3. Could be coil but do a compression test first. It is prolly a bad intake gasket as I just went through something similar on an 04 POS V6 Stang.