Bumblebee_GT

See what had happened was...

It all started with a feeling only the driver of the car can explain. She just wasn't running right. The only way I could describe what was happening is it felt like a loss of power. It seemed like more work than normal to accelerate and shifting wasn't smooth. The car started to "jack rabbit" and I've been driving it for 3 years without that issue. I know how to drive a stick.
I went to a shop who charged me $100 for a diagnostic which came back with nothing. They couldn't seem to find anything wrong with it. The mechanic suggested that one of the "butterfly valves" might not be opening/closing properly based on the issues I described and said I could try to clean out my engine with sea foam.
A few days after that my CEL came on. I ran by Autozone and they said the code showed my alternator was going bad.
I took it to a different shop recommended by a family member who said it wasn't the alternator, but that I needed new spark plugs. They replaced the plugs and the fuel filter.
A few days later my CEL came back on, the smell of gas fumes was coming out of my vents (it only happens when the car is stopped and it's strong enough to make me feel sick), and my car still wasn't driving any better than what I originally described.
Frustrated, I took the car to a third shop who told me my alternator was bad. They replaced it and gave me a new battery. They told me the fuel cap code was coming up and replaced it as well. The gas smell went away and no lights were on.

So here I am, about $1500 dollars into repairs. A few days ago, the CEL came back on (it's intermittent - AutoZone shows it's the gas cap), the gas fumes are back, and the car drives better, but it still doesn't feel right. Two new symptoms have cropped up: a slightly rough idle and the exhaust "stutters". Even when driving I can feel it. It sounds like air bubbles or something, it's not a steady growl like normal. My exhaust is not stock but it's given me no issue in 3 years. Also, sometimes when I'm taking off from a stop, my car shimmies or stutters and it feels like the tires can't grip the pavement. No, I'm not slamming the accelerator down either, this is just a normal take off. Strangely enough if I apply more gas when I take off it doesn't happen as bad.

With all that said, I have absolutely no idea what the hell is wrong with my car and before I go into a shop with this story I was wondering if anyone on here might be able to help me narrow down what's going on. I'm pretty frustrated at this point and I would greatly appreciate any help you guys can give me. I tried to explain the issues to the best of my ability but feel free to ask questions.

By the way, my Stang is a 2005 GT 4.6L V8

Thanks everyone!

BaltRavens

It sounds like the cats are screwed up and not allowing air to flow correctly. I mean I have no clue, because this is just guessing. It also could be fuel/air mixture? or the computer could be screwed up. I would just look over your exhaust system make sure everything is in working order. If your o2 sensors are bad the car will run like crap, and if the cats are screwed up? You will have a strong smell, and the car will run like crap as well.

craig71springsport

The rough running could be a multitude of things. Bad distributor/ignition system, clogged/bad injectors, bad valves, timing, fuel air mixture, computer problem...list goes on for basically ever.

The smell of gas in the car could be a leak anywhere in the fuel system. If it's coming from the vents it's probably in the engine bay, but since you said it's when the car is stopped it sounds like an exhaust leak. Check your entire exhaust system, those fumes are not very good at all.

Also, you said your garage changed your spark plugs? I'm not big on modular motors(which is what you have,) but I'm pretty sure you guys use coil packs on those engines rather than spark plugs. Check to see which you have, then go re-question the shop you got your supposed spark plugs changed. If they say they did your plugs and it turns out you have coil packs, demand your money back/free repairs or threaten to take legal action, the days of shops having car owners by the ***** are over!

Bumblebee_GT

I apologize, I wrote that post yesterday quickly at work and I didn't mean to say spark plugs. I meant fuel injectors and wires were replaced.
Also, as an update, my buddy & I checked the engine to check for signs of leaks and what not and the smell of gas fumes was strong on the rear passenger side of the engine bay. We checked the fuel lines and they seemed fine but as I said, you could definitely smell gas.
It seems as though I'm just going to have to go get it checked out and hope for the best.
If you've got em, keep the ideas coming, I appreciate it!

Lvnvgt

My car is doing the same thing... I just got it back from my buddies shop and ot had no errors or nething in the pcm. Yesterday while driving around with alot of stop and go with ac on it acted up by getting really sluggish and I had to damn near punch it to get it to snap out of its fit. I finally got a service eng soon light and it will be going back to my buddy to diagnose. Ill keep u posted and hope this solves both of our issues. Ive changed ething cept cps, tps, iat and maf. Ive tested the maf my self and it seemed to be workibg fine. He has the same program ford uses so hopfully now that I have a code itll be alot easier to diagnose.

Old Mustanger

Coil packs attach directly to the spark plugs, they do not replace spark plugs. Gas engines still use spark plugs to ignite the air/fuel mixture. So the OPs Mustang DOES have spark plugs.

DRAGUL

OP you're car uses spark plugs. All the ford engines uses spark plugs unless you have a diesel engine, then you would have glow plugs. The coil on plug set up is this, there is one coil that is attached to the top of each spark plug. So spark plug wires and distributor are eliminated.

FastBreak

If you even suspect the car has a fuel leak somewhere, be very careful with it. If something catches on fire, it can become a big problem very quickly. Also be careful where you park it. Putting it in a garage is a big no-no, bet even parking it too close to your house or another car is risky if you don't know how much fuel is leaking or where it's coming from.

Old Mustanger

Excellent advice! Good thinking.

PNYXPRESS

It sounds like a clogged catalytic converter. remove your h pipe to check. a clogged cat can/will cause an engine to grenade, just ask Boozshey.