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New gas cap - a 'performance mod'?

1240 Views 14 Replies 7 Participants Last post by  badass98svt
When I got my '02 GT a few months ago, the gas cap on it was broken. In fact, the part of the cap to which the handle is attached was completly gone, leaving only the cylindrical part that actually goes into the fill tube and the thin, circular piece of plastic connected to it that lays against the mouth of the filler tube. I immediately went to an auto parts store and replaced it with the correct gas cap, but not the locking model. Last weekend, I decided because of certain events I won't relate here that my Mustang would be safer with a locking cap, so I again went to a local auto parts store and bought one. When putting the locking cap on for the first time, I noticed that it seemed to have a thicker, heavier rubber gasket than the non-locking version. Since putting the locking cap on, I think that my car runs differently. It seems to accelerate more quickly and more smoothly, especially in fifth at highway speeds, and has a bit more power at take-off. I have accidently broken the tires loose slightly a couple of times when pulling out from a dead stop even though I am driving no differently and never did that before. I at first attributed that to wet pavement as it rained quite a bit Sunday and Monday, but it happened yesterday on dry pavement. Also, the exhaust seems to be a little quieter but 'throatier', especially at higher revs. Finally, I could almost swear that at lower speeds I can hear a slight noise that could indicate more air being sucked through my BBK in-fender intake. This sound has been there all along, but seems to be just a little louder now.
In addition to the new gas cap, I poured a can of Sea Foam into the gas tank when I filled up time before last. However, that tank was 3/4 gone before I noticed any of these things and I noticed them almost immediately after changing gas caps. I don't want to give the impression that any of these are huge changes - I probably wouldn't even have noticed the differences if I hadn't already been driving the car for a few months. I am just kind of curious more than anything else. Do you guys think this is due to the gas cap possibly creating more (or less) pressure in the fuel system or is it more likely due to the benefits of the Sea Foam? I am not ruling out the possibility that these things are a product of my imagination, but I don't think so.

BTW, I can't remember the company's name right now, but both of the gas caps are the same brand. If I get real industrious, I might dig the nonlocking one back out and put it back on just to see if anything changes.
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Your imagining it. You've probably had some colder weather come through your area and your engine is benefitting from the denser air.
it's all in your head man, there's no way a new gas cap is going to give you more power.
Monkey Boy said:
Your imagining it. You've probably had some colder weather come through your area and your engine is benefitting from the denser air.
I think you called it. It has been cool the last few days. Today, it was a bit warmer and I noticed on my commute home from work that my 'Stang was back to 'normal'. A couple of the older Fords I have owned and others I have had experience with wouldn't even crank when it was cold. Let the temp come up five or ten degrees, though, and they would fire right up. Changing the battery never made any difference - the were just cold natured. Imagine a Ford that actually runs better when it's cold! Guess if I decide to go to one of the 'Test and Tune' nights (that's what the tracks around here apparently call 'Run what you brung' night), I'll want to do it when it is as cold as possible!
lmfao...sounds like one of those ricer jokes.

"Dude, I just got 30 wheel HP with my new spoiler and "Sparco" sticker!!!!" :heha:
the98stang said:
lmfao...sounds like one of those ricer jokes.

"Dude, I just got 30 wheel HP with my new spoiler and "Sparco" sticker!!!!" :heha:
I do feel I had a legitimate reason for asking the question. I have known of more than one car, and even had experience with one myself, that on a particularly hot day would not crank even after multiple tries. Get out of the car, remove the gas cap and put it back on (the whole process taking less than a minute, so it had nothing to do with letting the car sit) and the car cranked right up with no hesitation whatsoever. This happened more than once. If pressure in a fuel system can keep a car from cranking and be relieved by loosening and retightening the cap, why could a tighter cap not result in a change of pressure that would have an effect on the way the car ran? I wasn't real convinced of this, though, which is why I asked and allowed that it could be my imagination. I do have to admit, however, that my choice for the title of this thread was intended to be a bit of a joke.
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JB02GT said:
I do feel I had a legitimate reason for asking the question. I have known of more than one car, and even had experience with one myself, that on a particularly hot day would not crank even after multiple tries. Get out of the car, remove the gas cap and put it back on (the whole process taking less than a minute, so it had nothing to do with letting the car sit) and the car cranked right up with no hesitation whatsoever. This happened more than once. If pressure in a fuel system can keep a car from cranking and be relieved by loosening and retightening the cap, why could a tighter cap not result in a change of pressure that would have an effect on the way the car ran? I wasn't real convinced of this, though, which is why I asked and allowed that it could be my imagination. I do have to admit, however, that my choice for the title of this thread was intended to be a bit of a joke.
No I wasn't trying to make fun of the post in general, it just reminded me of those jokes...
the98stang said:
No I wasn't trying to make fun of the post in general, it just reminded me of those jokes...
I see what you mean. Here's some - I just made these up, so they need work...

Q: Why do ricers spend so much money on HID driving lights?

A: So they can get a good look at the back end of all the Mustangs that pass them.


Q: Why do ricers like to have ridiculously huge wings on the backs of their cars?

A: So they'll have something to hold on to when they are pushing them out of the road.


Q: What is the difference between an import racer and a ricer?

A: You see an import racer and wonder what it will run. You see a ricer and wonder if it will run.

Okay, they're bad, I know. Guess I shouldn't try making up jokes at 2:00 in the morning.
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yer outta yer mind bro.

a gas cap is a gas cap, is a gas cap.
they're all the same.
lmfao @this thread
Underw0rld said:
lmfao @this thread
Same here... I just had to look!
Just so everyone is clear, although I did wonder if a tighter cap could make a subtle difference in the way the car ran, the title of the thread was intended as a joke. I hope folks realize that.
JB02GT said:
Just so everyone is clear, although I did wonder if a tighter cap could make a subtle difference in the way the car ran, the title of the thread was intended as a joke. I hope folks realize that.

rrrrrrrrrrrrright :dunce:
badass98svt said:
rrrrrrrrrrrrright :dunce:
Oh, no. I'm going to lose so much sleep tonight worried about what complete strangers on this forum think. Oh, wait, no I'm not. You might notice that I put in quotation marks as in 'performance mod' to indicate sarcasm - see - notice those little ' ' marks? Those aren't just there for decoration, you know. Oh, well, believe what you like - no skin off my a$$.
lol....boy noob, yer easy to get going...
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