I have a 09 G37 sedan with under 12k miles. On several occasions after a fill up of 93 octane Shell gas, the car will sputter at around 20-40 mph and will not go. It will thrust you forward. On 3 occasions, the car has completely stalled while going through and intersection. No power steering, nothing. Infiniti dealer has looked but to no avail. It only happens with a full tank of gas after putting about 20-30 miles on the tank. After it stalls, I have to hold the start button down a good bit longer than normal to get it to start back up. Anybody, anybody no what this might be??? It's now a safety issue with the car shutting off in traffic (in Atlanta). I have a 2 year old in the car most of the time. Any help would be greatly appreciated. Maybe the MAF sensor from other related posts I've read.

 

Sounds to me like the fuel pump is going, fuel pressure regulator is messing up, or the fuel filter got gummed up. Have you ever run out of gas or used really crappy gas?

Other reasons for this could be fouled plug(s), bad injector(s), IAC, etc. Neither of those are likely at 12k miles, and a full tank wouldn't make them better or worse.

Why not fill up right before you bring it in so they can duplicate the problem?

 

My brother was having all sorts of driveability issues with his M3, so he took it to the dealer and they said everything checked out perfect. They finally did two analysis of the gas and found it was 18% ethanol, which is way above the legal limit. He was buying Shell gas at the time. I used the same station once and got the worst gas mileage I've ever had from my G which confirmed it was being diluted with too much ethanol. You may want to try one of the other Top Tier gas providers...I'll never use Shell again.

 

Thanks. I have done just that. It is so random. They even installed a "copilot" for me for a month so if it did it again, I could press the button and the computer could record what was going on. It never did it and they wanted their copilot back. I'm taking it back in and will suggest the items you mentioned.

 

I only use the Shell because I have a corporate gas card and it's Shell. I guess I'll be trying something different. That's unreal. 18%?!?!?

 

Very strange, I get my best mileage out of shell V power in michigan. Guess it all depends on the gas station itself.

 

Yup...the BMW dealer checked it twice to make sure they hadn't made a mistake. I think they are trying to compete with QT and others in my area and can't match the price unless they water it down. I really need to call someone at the state to see if they can do spot checks of the stations in my area just to keep them honest. A lot of ethanol manufacturing plants have gone up recently and I'm sure their product is easy and cheap to get. It's too bad...Shell is running all those adds about adding nitrogen, etc. to make their gas great. I hope it's just my area and a problem across the country. The local Chevron stations are easily 10-15 cents more per gallon which makes me suspicious of the others.

 

I use Shell about 2/3of the time. I use it for 2-3K miles, then use BP for 2-3K. I've had no problems so far with either of them.

 

I suspect it was more likely an individual station issue rather than a problem with all Shell gas. And oftentimes multiple stations within a local area share the same owner.

 

I'd switch to 91 octane for a couple of tanks and use a "total fuel system cleaner"
like Techron in the first tankful. 93 octane isn't needed in this engine. The
high knock index of 93 octane could be "confusing" your ECU in your particular
driving conditions.

 

Might not be possible. Many stations offer either 91 or 93. I've seen 92 in some areas as well. It often depends on what state you live in.