Hello, ALL - I am new to the forum, but a proud owner of a 2012 G37, which I bought in perfect condition around 2015. So, here's my tale of woe. I took it out one morning, started bucking when I accelerated and gave it gas. ServiceEngineSoonLight. AWFUL SMELL.
Drove straight to the mechanic. Left it there, diagnostic code showed CAMSHIFT SENSORS, which they replaced. Paid $450 - drove home fine. Next morning - would not stay started. Meaning, sounded like the engine turned over, and then give it gas...chug chug...off. Repeated this a few times. (Battery new, electronics good/on). Terrible smell. Towed it back to mechanic. He sat in the car, told me it rained yesterday, there was moisture in the engine, and VOILA - he got it started and idling....He said you're lucky, tale it for a ride, and if its good, go home!
As I pulled off the lot, he called out to me...………MOTOR OIL LEAK PUDDLE UNDERNEATH!!………….Pulled back into shop - after an hour, comes out, "wow, what a luck son-of-a-bitch" It seemed your oil filter was corroded, and pieces frayed inside, so did an oil change and replaced the filter (said he thought it was the engine seal, but lucked out)……. Paid for the oil change $45 bucks..... Pull out the car....Drive 2 blocks.....HEHAW, the buckin bronco is back...U TURN - back to the shop.....He gets in drives, and says, ok, leave it overnight...…….

Now, he's NOT sure what it is. First, he tells me its 80% fixed, and I ask what he's doing - he said no codes - hes FLUSHING THE ENGINE (thinks the sensors aren't clean, etc.) I'm thinking, should he be flushing the engine on this kind of modern car???
I call at end of day. Car's staying, we're still diagnosing it..."Car is having VERY SERIOUS PROBLEMS" I'm thinking WTF? Now, I was afraid to make suggestive statements or else he'd just start changing everything. I was thinking what could it be? I'm a novice, but thinking - spark plugs (nah that's the easiest thing to check), fuel injection clog, knock sensors (had this once before in another car that behaved this way), coils?

I'm getting nervous what it could be, and that a mechanic in business 30+ years, doesn't know what it is. Another issue I had (not related, but who knows and just saying), my gear shifter had issues when in PARK, didn't recognize it, and I had to keep shaking the shift gear to make it "connect: or else the ALARM would ring and I'd have to disconnect the batter (negative charge) which resets my computer. I was gonna fix this, but then the above issues happened.

ANY IDEAS? Is the mechanic on the right path, or should I get the HE-double-hockey sticks out of there? THX

 

Take it to the dealer. They'll be able to hook up consult with live data.

 

So, Obi-Wan, here is what the mechanic said. Due to low-oil or lack of oil-changes, there is sludge in the engine. They flushed the engine, and they said the "sludge" were causing the sensors and timing to misfire. IE the timing was off.....Thoughts?

 

Hope you didn't buy a flood car.

Check your grounds.

Bucking and jerking, but no codes? Something odd. Time to pull the spark plugs and see what maybe going on. You could be running on just a few cylinders.

 

So...is it low oil or negligence? You'd have to drive the car for quite awhile on low oil for that to cause sludge. Not changing your oil on the other hand...Have you changed the oil since 2015?

As tea head said, pull the plugs; I'd even recommend you move forward with removing the valve cover to see how bad it is. If it is sludge build up that is...