I had an A&A put on a few months back, no issues. But one day, I drove and got gas, and immediately after leaving the gas station, the car was sputtering. Exhaust was backfiring a little, but the car felt like it had no power and was just hesitant on throttle and just sputtering. After about 100 miles (was coming back from a trip) it cleared up and no issue since (thought it was a bad tank of gas). Fast forward to today, I drive car to my destination and no issue, car sat for a few hours, and then started it up, pulled away, and the sputtering was back again. Kind of cleared itself up but I can feel the power just isn't there, like it's delayed, and some sputtering again. Any ideas? Could it be the tune? Fuel issue? Spark plugs? Bad tank of gas? I'm little less than a 1/4 tank so wouldn't think that's the issue. The car did sit for about 4 weeks, just backed out of driveway that was about it. I can't describe it any better than feels like it's sputtering, stumbling, hesitant, skipping, surging, etc. at low speeds. Pulling away from a light and giving it gas it's stumbling and sputtering, and just not a whole lot of power. No lights, no fumes, no smell, no smoke. C7 GS manual, made 580/552 on 93, low boost (6lbs), headers and catless xpipe, ported tb and intake manifold. Tuner said I don't need fuel system upgrades staying under 600hp. Thank you

 

Your issue may be a little difficult to nail down without having some diagnostic equipment with a scan tool being the minimum so the best you can do is replace some parts if your concern continues…are you still on the same tank of gas with the stuttering and throttle response ??…yes it could be some bad gas since it started when you filled up…since the car sat and if you still had water in the tank in which it will sit at the bottom of the tank the car will continue to run poorly….so it may be plugs, wires, O2 sensors, MAF or MAP sensor to name a few…it may be cheaper in the long run to take the car to a diagnostic shop…NOT a general repair shop or a dealership…you can pay for the diagnostic time and do the repairs yourself if you can turn a wrench.

 

How long of a time period is this occurring? Several days, Several weeks, several months? How many times have you filled the gas tank since you first noticed the problem? What was the fuel gauge reading before you filled the tank?

Remember the C7 has two fuel tanks and there is no effective mixing of fuel between the two tanks. If you filled up with gas when the gauge read more than half full any bad gas you received went into the passenger side tank. When the car is being driven the passenger side tank is emptied first. If you got bad gas when you filled up you could have an engine issue until the gas in the passenger side tank was gone and the engine started using good gas from the driver's side tank. The next question is did you fill up again and what was the fuel gauge reading before you started the gas pump? Did you fill up at the same gas station? If you fill up at a station that doesn't pump a lot of premium fuel you could easily get more than one shot of bad fuel if you fill up at that station several times within a few days.

As C5 Diag recommended you may need to have somebody diagnose what is wrong with the car but understanding how you fueled the car and how much fuel you put in may help a lot in determining whether you got a bad batch of gas or something else went wrong. Bad fuel can also damage parts in the fuel system so you really need to understand in depth what you did when fueling the car.

Bill

 

My tuner thinks it may be a bad spark plug wire, so we are going to replace all of them. As for the gas, the first time it happened in like June, I filled up at a Shell station. We were in the mountains for the weekend and I filled up at that same station multiple times. My last fill up for our ride home, maybe I was at 1/2 a tank. Immediately after I pulled away from the gas station the stumbling occurred. I pulled over, rev'd it a bit (not too high) and you could hear it sounded odd. Over the next hour, it gradually improved itself until it was perfect by time I got home (3 hour total drive).
The other day, I drove it to my destination and no issue. Sat for about 5 hours and as soon as I pulled away I could feel it stumbling/hesitant. I got home and seemed to get a little better but its only a 30 min drive. I do need gas now as it's close to empty. I thought about throwing in a bottle of Techron complete fuel system cleaner. I usually fill up with Mobil 1 or BP.

 

Sputtering, backfire, loss of power, hesitant on throttle all sounds like spark plug issues. My car felt like it was down 100whp or more. Would backfire and sputter even when giving half throttle. Changed all the plugs and it was back to normal. A tuner should be able to log and tell you if you're getting misfires and where. My shop guy pulled one plug on the driver side and said it was okay. My tuner was able to see the issue was a plug on the passenger side and there were signs of detonation on the plugs there.

Also are you filling up on cheap gas? I feel like bad gas isn't something that you should really experience if you're filling up at top tier stations.
No reason to suspect tune if it's something that just started happening.
Your injectors could be getting clogged, but the spark plugs are far more likely the culprit imo. Some plugs can go bad in just a few thousand miles.