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Multiple issues my car is having

5K views 102 replies 11 participants last post by  straybullitt 
#1 ·
Car is an 03 mach 1... first im running the factory catback but dumped before the axle because a catback i bought didnt fit right before i went to mw so i had to throw the factory mufflers back on and the car is now hesitating at wot and second the check fuel cap light is on and ever since it's been on the smell of gas has increased but the car is running a little better. Just wondering if it's bad to be driving it with those issues and how can I fix them?
 
#2 ·
First, the smell of gas is always bad. If your gas cap seems okay, you have to get under the car and inspect for damage to the fuel lines. Doing exhaust work might have accidentally damaged a hose or fitting while under there. It happens.
I realize some people live in an apartment complex and you aren't allowed to do car maintenance. One way or another, you need to get under there and inspect for leaks.
 
#7 ·
There are a few guys around me running open pipes, no mufflers after the cats. You should be fine that way.

The cars I have heard sound horrible, but that is my personal opinion.

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#15 ·
Backpressure is a myth. Your engine doesn't need it to run properly. It does, however, need a properly sized exhaust system to promote a scavenging effect on the exhaust.

Your engine will run better, and sound better with a complete exhaust system. But I see no problem with running the car without the mufflers and tailpipes. With the exception of blasting the underside of the car with hot, loud, exhaust, of course.
 
#16 ·
Exactly. Thank you for the clarification Stray.

You will have to forgive my lack of termonology. Due to an infection in my jaw (broken wisdom tooth that caused complications) I am in the comfort of oxycodone. I get to go back again tomorrow for more abuse.

The Oxy and I do not like one another. I prefer a sober mind. My head is nowhere near clear at the moment. Oddly I am not tired. For some reason I am full of energy, but I have no coordination. Drugs are not my friend.

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#20 ·
The X pipe could be causing things to run lean for some reason. You could also need new plugs, fuel filter, etc. If you think the exhaust caused the problem, swap it back out and see whether or not it clears up.

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#23 ·
You do not have to have a tune on 94 - 04 Mustangs when you change your exhaust.
I've owned a 94, 96, 98, 02 & 04 & have put X-Pipes on all of them. 2 - I put Headers
on also. You said you still have your cats on...right? I'd tap on them with a rubber mallet to see if they might have clogged when you changed your exhaust. That will cause hesitation. The gas cap I'd change right away. Remember...you have to drive the car about 50 miles before the computer resets itself. Your Cap could be your problem. Probably where your smell is coming from. If not check the Rubber Gasket around the filler neck where it meets the tank. They are notorious for dry rot, smell & eventually leaks. The other thing it could be is one of your sensors is dirty. MAF Sensor would most likely be the one if it were a sensor. Just a few starting points to find your problem. Hope it helps.
 
#37 ·
The gas tanks on the new edges tend to leak at the fuel neck down where it connects to the tank. Mine was replaced last year for this problem. I had less than 60k miles at the time. If you still smell gas, I'd look into to that. You can check for leaks in hoses and the evap canister itself. That could cause fuel smell too. According to AllDataDIY, it's located under the car on the drivers side rear. It says to remove the driver's side wheel to gain access. I think I remember seeing the rear of it on the backside of the rear wheel well.

Auto part Fuel tank Vehicle
 
#43 ·
The 4.6L 4v's didn't have plastic intakes, so I doubt you have a crack in your intake. It doesn't hurt to check.

Read this I posted below. I'd work on finding the gas smell first. Mine leaked where the fuel neck goes in the tank. I needed a new tank. After that, look on the drivers side rear where the evap canister is. If it leaks, I believe it will cause gas smell too.

You should probably use your tuner I grab all the CEL codes you have. That way you know where to go next.

I couldn't find a diagram of all the vacuum hoses, but you can start at the top of your EGR valve and check the hoses back up the system from there.

The gas tanks on the new edges tend to leak at the fuel neck down where it connects to the tank. Mine was replaced last year for this problem. I had less than 60k miles at the time. If you still smell gas, I'd look into to that. You can check for leaks in hoses and the evap canister itself. That could cause fuel smell too. According to AllDataDIY, it's located under the car on the drivers side rear. It says to remove the driver's side wheel to gain access. I think I remember seeing the rear of it on the backside of the rear wheel well.



View attachment 204337





Instagram - @ab_mach1
 
#40 ·
Check for vacuum leaks and cracks in the manifold. Also make sure there are no air leaks after the MAF sensor.

I am new to Ford and modular engines, but I am learning that this particular design is extremely sensitive to any changes or minor problems.

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#42 ·
Be patient with me and I will answer in a bit. I'm dealing with pain meds at the moment, and I am not thinking clearly enough to give you answers I trust.

I am betting that someone else comes along shortly though with the answers.

I would begin by looking for physical cracks.

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#44 ·
Yeah I was just wondering if there was a way to check for leaks without having to jack the car up and physically check the lines. I don't have a tuner on the car btw I have some $30 thing that reads codes

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#46 ·
The $30 code reader thingy will work fine.

Unless you are physically, generously proportioned, shall we say... Or your car is very low... You should be able to squeeze underneath the car with a flashlight, near the fuel filler tube, and inspect it for any signs of fuel leakage, rust, rot, disconnected hoses, or any other sort of damage.
 
#47 · (Edited)
Haven't had time to check out the gas smell but a couple of new issues have came up that concern me, first the car is now starting to pop at w.o.t and it still has a slight hesitation around 4k rpms. The idle is also not sounding right like it's idling normal then all of a sudden it'll sound like it stumbles. Also 2 other incidents happened where I came to a stop and the car started idling at like 600 rpms then it went away after I took off, then last night it barely cranked up after I moved it just 15min before

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