MPdesign

My 2008 G37 is not running so great.

It has been doing this for months. I thought maybe it was water in the gas so I added dry gas, changed stations, etc - but it is still doing it months later.

When the car is in 5,000+ rpms, it still revs smoothly, but it sounds like it just skips a few fires - this is what I would assume it would sound like if there were water in the tank that was hitting the cylinder, that cylinder doesn't fire, and the rest are still firing fine.

It also seems to do it much worse when it is freezing outside.

I took it to the dealer, they checked t out, had no codes for trouble, couldn't recreate it (they probably did a little sunday drive around he corner and never got into the high revs - was with my wife and I had to go without leaving it longer). They found no problem.

Anyway - have u guys had this problem?

GW330

iTrader: (1)

I would change spark plugs, no engine codes either?

beers64

iTrader: (5)

could be a few things. plugs would definately be an option. also depending on mileage cleaning the throttle body may help. i know you changed fuel and stations but if your not already doing so a higher octane may help. also, in the dealers defense im sure they checked it out as best they can without duplicating the problem, usually places like that dont get payed unless they find the actual issue and perform the fix. hope that info helps. good luck.

MPdesign

Thanks guys. No codes were showing.
I do think my dealer does a great job usually, I will make sure they see it next time.

I am coming up on my 100,000 mile scheduled maintenance, so I really need to do most of that anyway. Thanks!

Let me know if you have any more ideas - or if anyone has had this problem.

Cheers - have a good weekend.

MPdesign

I am really not interested in spending even more for gas- that is not an option.

beers64

iTrader: (5)

what octane level are you at currently

MPdesign

I always purchase Premium. usually 92-93.

I have NEVER purchased anything less for this car.

beers64

iTrader: (5)

well then that seems pretty damn sufficient to me, probably not that or gas related in that sense since you have already swapped stations. id say start with the plugs then the throttle cleaning

TVPostSound

iTrader: (9)

First thing, and I mean first thing.............

Fuel filter.

beers64

iTrader: (5)

^^^^^^^^^^That might be a pain in the *** but at your mileage it may be needed but those usually dont go bad too often. I think the fuel filter is built into the pump itself. Is there an external one? Or will the whole unit need replacement?

KAHBOOM

iTrader: (4)

found this via search.. Mine has been doing the same thing.. Most prominent when its freezing outside as well...

Dealer said it was "normal" after checking with Infiniti tech line.. Not accepting that.. After the car warms up it goes away, but if this were "normal" I would not have purchased the car lol... Anyway, I am wondering if the OP identified the issue.

A few circumstances underwhich the noise occurs..
1) Its not so much a sputter as it is a slight thrashing sound.
2) Its always under 40 degrees when it occurs.
3) Problem normally goes away after car has been driven for 30 plus minutes
4) when occurring, actually gets more pronounced when momentum shifts over bumps
5) Only occurs under load.. cannot duplicate when car is not moving.

I wonder if its something to do with the radiator as it attempts to warm the engine when its cold. Issue never occurs during warmer months...
Last time I had an issue that Infiniti could not diagnose, I took it to a Nissan dealership who figured it out right away.. maybe that's the route I should take again

MPdesign

I have not had this issue fully resolve. It is still there, but it is not as bad now. It has been many miles and many months.

I did go through the full 100k miles items and had the throttle body cleaned.

Cheers!

KAHBOOM

iTrader: (4)

Was your noise from the left side. That's where mine is coming from

MPdesign

I am pretty knowledgeable on cars and determining the areas, I would have to say that this is a general engine noise - not side specific.

I will test it out again in a few minutes.

KAHBOOM

iTrader: (4)

update.. took my left air box off and put it back on.. the airbox was not tight on the left side. The airbox was not sealed tightly to one of the intake hoses. .. now the issue is resolved completely.