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KarnoDal · 02-07-2015, 05:54 PM

Hi all,

I have a 2014 Mustang GT that I bought in July. It has about 9100 miles on it. I took it out this morning and noticed it was running a bit rough out on the highway. It was shuddering/choppy when accelerating and backfiring when I shifted/let off of the accelerator. Turned around and took it straight to Grapevine Ford (where I bought the car), but they haven't been much help so far.

I have a Steeda CAI, BBK 85mm throttle body, BBK ceramic long tubes, a custom catted H-pipe, and MBRP race series cat-backs on the car, and a Bama tune. The tech at the dealership basically refused to even look at the car with all the after market parts on it, told me he couldn't help me since I wasn't throwing any codes. Suggested I call the place I had the mods done (Dallas Mustang) or the place that did the exhaust (B&G) and get them to check it.

B&G found no leaks, but while they were checking the car, the check engine light came on. The tuner showed it was code P0302, second cylinder misfiring. Turned around and took it back to GF and showed them the code and they still said there was basically nothing they could do, since they don't know if the coil is throwing the code or the after market parts are generating the code and making it look like a misfiring cylinder (if that's at issue, wouldn't checking the coil tell you? It's either bad or it isn't.).

I still have my factory airbox kit and throttle body, so they asked me to bring those up and let them put those back on the car and test it. Already felt like I was getting the run-around (I know after market parts can cause problems with diagnostics, but seriously, refusing to even look at the car because of it?) and felt even more like it when they quoted me two hours of labor to put the stock parts back on (no way that's a two-hour job. Took about 30 minutes to have it done, initially). Seriously concerned they're going to do the swap, spend a few minutes driving it and tell me they still can't tell what it is because of the headers and exhaust mods and hand me back the car and a $200 bill.

Any thoughts on what the problem may be or how I should approach the dealership? I'm really surprised. Grapevine had treated me really, really well up until today.

Thanks,

C-