love the new car, but having a problem with weird gas noises
 

Hey all :) So exciting to own a 2009 370 Z!! It's been my dream car for as long as I can remember, can't believe it's finally mine. I've had the car for about 8 months now and it just started having a noise issue that I was hoping someone could help me out with. The local Nissan dealership had no answers (which was upsetting, since I bought it Certified pre-owned).

When I am stopped in traffic and put my foot on the gas to move slowly forward, I hear a horrible farting noise that sounds like it should be eminating from a 1992 truck and not my perfect little Z. It goes away after 3 or 4 seconds. It happens about 30% of the time that I am going from stop to start. It sounds like a nasty chug-a-lug sound of a car that is about to die. Other than the noise, there are no complaints. My car is otherwise perfect. It drives and handles great.

Nissan suggested the previous owner did not use premium gas and it probably has a build-up of something that will eventually work itself out as long as I continue to fill up with premium. A friend suggested I dump Techron into the tank before my next re-fill. I have ONLY been using premium 93 gas, I'm not sure how this happened now and not 8 months ago if it were the fault of the previous owner. :icon14:

This has been an ongoing issue for the past 6 weeks and I would love hearing someone else's opinion! Any suggestions?

Is the car an automatic and where does the "farting noise" sound like it is coming from (tailpipe, under the hood, person in the passenger seat :rofl2: (sorry, couldn't resist?))

Does the car shudder at all like it is going to stall, and do you see the RPMs fall at all?

A lot of questions, but I am only trying to help narrow down the possibilites.

typical Nissan, avoid any warranty payout

The noise definintely comes from the back of my car, and what I am assuming is the tailpipe. (occassionally from the passengar seat as well...LOL) It's very loud....but my car doesn't shudder and the pressure on the gas pedal feels smooth (there are no jerking motions). Not sure about RMPs but I will check it later today when it happens.

Is it like a hissing sound? I know you said farting sound, but if its like hissing,
does the car have stock exhaust? Are the cat converters stock?

And just to clarify another thing, you said chug-a-lug, do you mean you hear
a chattering sound like 2 small metal pieces clashing when on idle? If the
chattering chug-a-lug sound is separate matter from the farting noise, then
what you are hearing is an early release of the clutch. We have the noises
clutch of all cars.

If none apply, get a 2nd opinion from another dealership. Do not mention to
the other dealership that you had this inspected, see what they say.
If the 2nd opinion ties to the first theory, then you as a certified pre-owned
buyer should not be dealing with this. Nissan needs to flush the system to
get rid of that build up. That build up sounds like you're about to get bad
mpg.

Nissan dealer's suggestion is stupid. 6 weeks = it's not "working itself out."

The noise is unacceptable. A "certified" car with issues 8 months later that are supposedly due to previous owner's negligence is unacceptable. Either way, take it back and tell them to fix it. If the noise is reproducible they can diagnose and fix it. If they aren't willing to, then take it to another dealer.

it is definitely not a hissing sound, nor is it the noise of metal hitting metal. It literally sounds like my car is choking on something - sounds like a thick liquidy gurgle. I drove around the block with a Nissan representative and we were able to reproduce the sound more than once.

I also should've mentioned that this only happens when I am going from a stopping position to a slow start (like, in traffic). Doesn't usually happen first thing in the morning. Also, I live in Boston where it isnt usually too hot so it isnt an overheating thing either.

How much mileage the vehicle has? Check your mileage and look at the owner's manual.
Ensure that the dealership has done all the necessary fluid changes like transmission flush,
differential flush, etc based on your car's mileage and ask them any paperwork that shows
proof that they actually did it.

No one knows what is exactly is going on, but everything can be put into consideration
right now because its safe to assume that that farting noise may transform into a bigger
headache.

Things I would personally consider if I were on your shoes: differential oil turned into mud,
engine oil turned into mud, cat converter failed, or worse, someone has stuffed something
in your exhaust.

30,900 miles on the car right now. When I went in to check out the noise 6 weeks ago, it was also time for my oil change. I chose normal oil instead of synthetic, because the Nissan guy said there would be no benefit to synthetic. They said it was time for my "fluid flush" which we did in the same visit.

Also, upon purchasing the vehicle, the Car Fax report looked great - the previous owner had seemingly taken good care of the car - oil changes on time.

Manual or automatic?

If it's a manual, it might just be clutch chatter, although I don't think that would sound like it was coming from the rear.

It's automatic. Today someone at the auto parts store sold me some gas tank cleaner, saying it would clear out any build-up that might've accumulated over time. If this doesn't work, back to Nissan we will go.

What is this normal oil they gave you? People will say any oil is fine, but getting the proper oil will dictate the longevity of your engine. Haters can hate, but when I say proper oil, it does not have to be the Nissan Ester oil.

No disrespect, but Car Fax is garbage. I can buy a new car, mod it, thrash the hell out of it, wreck it and still trade it in with a clean title. Not every service/repairs gets reported to them.

Anyway, back to the topic, get that 2nd opinion asap. The more conclusions and assumptions happening, the more paranoid you might be. I'm sorry to be blunt, but deal with it right now than later that will waste your time and money, and worse, Nissan might say its your fault and they wont cover it.

Thank you everyone for your help and suggestions! I will definintely be dealing with this matter asap, and will let you know the outcome.

nissan guy should find another career !

Stick with synthetic, that rep is an idiot. Please don't fall for any type of "fluid" flush unless you know what you're getting done. These guys will sell you everything on the list if they had the chance. Read the manual. It has everything that says what needs to be inspected or replaced. For the most part, you won't have to do much exept oil changes and air filter changes.

The issue with the noise could be a lot of things. Is the car 100% stock? Did they inspect the exhaust system? Did did run a diagnostic? if so, any codes?