Hi there. I am hoping someone might be able to give me some advice on how to proceed. I have owned my G37 since last Summer and really haven't had any major issues with it until now (and I am not sure this counts as major). Last week I had my first oil change since the purchase. Car has around 107K miles and is overall in excellent shape. The oil change might have nothing at all to do with anything and could be a coincidence. But shortly after, I threw a code for lean fuel. I had that cleared at the auto parts store but now the idle is really rough. At lights it will drop down to like 500rpm and it feels like the car is jumping but I don't think its a transmission thing (but it could be). It doesn't seem to be pulling as well and sometimes it will hesitate really badly. I have an appointment with the dealer in a couple of weeks for something else but I called and they are aware I am having other issues. I took it to another car place today and they said the air filters were dirty, the MAF was dirty and they wanted to bench clean the throttle bodies. They also wanted like $900 to do so. I paid the diagnostic fee and picked the car up. I can clean those things myself, and I saw the air filters in the past few days and they are not that dirty. I bought new air filters and throttle body cleaner but I would be really surprised if this is causing the behaviour. I also did the "idle relearn" as seen on youtube but it doesn't appear to be helping.

Any advice or input would be much appreciated!

 

Throttle bodies. Check MotorvateDIY on YouTube. Clean them and do the relearn and you'll likely be good to go.

 

That is good news! It seems like a pretty minor thing, and it confuses me as to why it was so sudden, but I watched the videos on how to clean that and the MAF sensors and I will do those tomorrow first thing. I also already bought new air filters. I was really worried it was something serious like the dreaded gallery gasket. Thank you for your response!

Edit:
Just watched that video. I had watched the one in the DIY section here but man that was a fantastic video! All three procedures to do and very informative. Subbed. Thanks!

 

Follow up:

Today my car threw nine codes:
P010b (x4)
P006a (x2)
P0171 (x2)
P0174
These all seem to be MAF exceeds specifications or fuel too lean. The car was barely drivable and died more than once at idle. I was debating towing it to the dealer or trying to go ahead and do the things that the shop was going to do. I went ahead and replaced the air filters, cleaned the MAFs, and cleaned the throttle bodies. I also did the three things in that video and reset the ECU (which might have made the other things redundant). I tried several times to do the gas pedal turn on and off the car way to reset the ECU but ended up just disconnecting the battery.

So... on the way back from my aunts where I did the work, the car was running much much better. Really about normal except for a couple of things. At one point, while cruising on the toll road at 80, I noticed the check engine light blinked. It didn't stay on, and it only blinked once or twice but it blinked. I didn't know it could do that and not stay on. Also, at idle, I noticed the idle was ever so slightly changing and seemed to be doing the same kind of lurching, except now it was almost imperceptible. If this keeps up I will still take it to the dealer ( have an appointment anyway a week from Monday) but it seems drivable. Maybe the car is just learning its new parameters? Or maybe something is still wrong? I noticed something like sawdust seemed to be in the intake and maybe that somehow got into the MAF?

 

So yesterday my G got me all messed up, got up in the morning, took the car to work as usual and ntg happen, at the end of the day, went back to the car and drove home with no issues, had to get some groceries, turn on the car and it’s like choking and shaking a lot, rpm were getting really low so I gave some taps on the gas, went back to normal, after I came out from the supermarket, same thing happens, and suddenly the idle goes to 1000rpm and CEL turns on.
got one of those cheap FIXD scanners some time ago and went to check the codes, got a P0171, I turned off the car turn it on without starting the engine and cleared the code, started the engine after that and same thing happens, only this time I start hearing some knocking from the engine, popped the hood and tried my luck, disconnected the maf one at the time and the knocking stopped, cleared the codes and everything back to normal but only this time shows up P0174, but no rough idle, no CEL, nothing, everything normal but the code was still there, went home, and cleared the code.
this morning like usual, got into the car, started the engine, everything good, went to check if any codes would show up, nothing, drove to work, no issues at all, after work came home, no issues, as soon I turn off the car and some time later I turn on, same thing happens the shaking, low rpm, choking.
so I’m kinda lost right now, no idea if it’s the maf, throttle bodies, o2 sensors or something else.
also I have no idea if it’s some sensor, but apparently I’m getting about 21L/100km, like I filled up the tank 2 days ago and got 399km of range, drove about 50km and now my range is 298, but the needle only dropped one “line”, usually I shift around 2k rpm, I see on the dash that the bar never goes over 10-15, only when I stop and go(red lights)
btw my G is completely stock, for now
any ideas or solutions would be greatly appreciated

 

I don't have any solid ideas but I can tell you what happened after my last post. I took it to the dealer and they replaced both MAFs. Problem solved . You might try cleaning them like I did. That might help or might not. With the FIXD sensor (I have one too) you can get quite a bit more data than just the codes. Look into the data a little more. That might give you a better clue, but for me I had both sensors swapped and haven't had any issues since then.