I've posted on here a couple of times about the "stammering" or "uneven acceleration" issues I've been having with my 2012 GT. I think I may have found the root cause of the problem. At least I hope so.

I absolutely love this car. Since buying it, I've been filling the tank at my local Shell station. Two days ago, my tank was just about dry, so I pulled into my local Phillips 66 station and filled her up. Also immediately, upon driving out of the lot, I noticed a difference in the response of the car. It seemed to have more power, was more anxious to use it, and when I obliged, there was no hesitation or stammering at all. For the past two days, it's been running like it should, perfectly.

Is it possible that there is something in the Shell gasoline that was causing my car to perform in that manner? Could it be that simple of a fix?

Input would be appreciated if you have any.

 

What octane level fuel are you using !

 

Yep it's possible. I stay away from shell in the mustang. Usually chevron is what I use.

 

Indeed it is possible, although in a FI car, it's less of an issue, seems like to me. Doesn't mean it's not possible.

I had to run Exxon or Texaco ONLY in the '66 Thunderbird. I never understood why that was. Ever. If I ran *anything* else in the car, it really didn't like it, and it was obvious.

Awesome doesn't seem to mind different gas... so far. But I buy good stuff, and stay away from seedy lookin' places. Chevron is my favorite though, by far.

 

The highest octane at both Shell and Phillips 66 is 91.
I can't find a station here that sells 93 octane.
I'm also wondering if Shell might have ethanol in their gas.

 

Just about everyone has started mixing ethanol in their fuel. That might be the problem but I would bet on the detergents shell uses.

 

Could be fuel pump issue...when you used shell gas did you always fill to top...and if so did it still have issues when full?

That said with all my older foxes if i use chevron...they just run better!

 

I only use chevron myself. For various reasons.

 

I can't imagine a fuel pump issue at 1,200 miles.

Yes. I always fill till the pump clicks off. Then start it again until the second click.

I'm going to keep using the Phillips 66 and hope it keeps working like it has.

 

The correct answer is YES, it is entirely possible that the Shell station you have been using has bad gas that doesn't work well in your car.


The car I had before my Mustang was an Infiniti G35. It required premium unleaded only, and was very picky about the fuel that went in it. Even switching between the "summer bend" and "winter blend" of fuels required in Texas showed a noticable difference in both performance and gas milage. It ran great when I used Exxon or Mobile gas, but if I bought gas from our local Kroger grocery store it would cough and sputter and fuel milage would drop by about 10%.

So again, the answer is YES. It is entirely possible that for whatever reason your car simply may not like the fuel that your local Shell station sells.

 

Funny thing is my old F150 with the 4.9L I-6 doesn't like Shell either. It will ping on Shell but not on other gas - incl the high volume cheap station I've been using for years.

What the heck is up with Shell?

 

Hmmm..I run nothing but Shell 93 in mine...I may have fueled up with Mobil once in 11,000 miles in a pinch.

I suspect if this is related to "bad gas" it is unique to that station and not Shell's blend.

SterlingGreyV8, did you get a CEL? If this problem was from incomplete combustion/bad gas, its very likely that you would have gotten a flashing Check Engine Light...

 

Its quite possible it's the actual gas station your going to. Depending on the age and how good the tanks are maintained at particular gas stations, that can contaminate the gas. I know in my younger days when I was working at a station we had to check for water levels in the tanks due to condensation. Depending on age and conditions of the tanks is definitely a factor.