Bad Plugs or Bad piston?!? Help

01Stang65

New Member
Jan 19, 2017
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I am going to try to be as thorough as possible. I am going to list all symptoms since I have owned the car.

I bought my 2001 GT with 47k miles on the odo. The car now just passed 70k. Since then I have done an O/R midpipe/catbacks, and changed the plugs once (went to autolite which I regret doing). When I installed the exhaust I noticed a hush sound of "air flow" below the passenger seat. I assumed it was a small exhaust leak, never got around to doing anything with it as it seemed harmless.

This is where it gets rough. Ever since I owned the car, I have had an issue with it starting up every once in a while. Sometimes after it would start, it would almost die immediately. Never had an answer for it and it never seemed to cause any real issue. Last year I did a 3-4 gear pull and at the top of 4th gear the car misfired bad. That is when I installed the autolite plugs. Last night, I went to do a 3-4 pull, and when I got on the brakes right after the pull, I completely lost power steering, brakes, lights, and I couldn't hear the engine anymore, so I figured it shut off. I went to turn the key as I was rolling to realize the engine was still running, just at very low rpms. As I tried to put the engine into 4th, the revs were super weak.

There is a ticking coming from right behind the passenger wheel, and I can hear it out the exhaust. I am thinking this is the exhaust leak I was talking about earlier. That can be fixed. However the spark plug on cylinder 6 (3rd one back on passenger side) had zero gap in it when I pulled it out. All the other plugs were fine. I stuck a coat hanger down the cylinder and hand cranked the engine to feel for piston movement and it was moving.

There was a small knocking coming from the other side of the engine bay, but I almost think it is a loose engine mount, the car seemed to be shaking pretty bad.

I'm looking for possible suggestions and past experiences. I will be getting a borescope down in the cylinder sooner than later.
 
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01Stang65

New Member
Jan 19, 2017
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Is it possible you were given the wrong plugs causing the Piston to slam into the plug? Does your exhaust almost sound like a mild cam?
I thought about that but they were the correct plugs... Just autolite. The exhaust didn't exactly sound right after the misfire, but I have a bad leak somewhere, I wonder if I is talked the gasket backwards when I did my midpipe 2 years ago, I don't do hard pulls often and maybe it blew that gasket. I'll install the gasket tomorrow morning and see if that takes care of the ticking.

Either way when I fix the misfire with these new plugs I'm taking it to a shop to have them examine the inside of the cylinders