Not exactly how I planned my first post to be, but here we go. Sit back, grab some popcorn, and feel free to read on.

I have a 2005 G35 sedan 6MT with just over 90k. I bought it used at 86k in July of 2015. Bought the car bone stock. Since purchasing, I have thrown Stance SuperSports and 20" Niche M161's on it with some other 'mods', and also a rear muffler delete, other than that, nothing performance/engine wise though.

Lately, the car has been nothing but headaches, agony, and confusion all while it seems as if the car is laughing at me

Have had the SES/CEL come on multiple times on different occurrences for different problems/issues. Anytime I've had issues with the car, it seems to be the same thing. Idling rough/erratically, high/low. Being a 6MT, when taking off in 1st from a stop it will hesitate/misfire/stutter whatever you want to name it. Also, whenever driving the speed limit (anywhere from 45-55 around here) and being in 6th (or any low end of any gear) and giving it anywhere from half throttle to WOT, the car misfires/stutters/hesitiates/etc. And lastly (what it has been doing most recently), is what seems like a misfire at idle just after start up when the car is WARM/AT OPERATING TEMP. Start it up, the car will have a small shake/jump for the low/misfiring idle, then when feathering the throttle it will misfire.

Now, with all of those symptoms happening, here's what I have gone through, fixed/replaced, and found.

IIRC, the first code it ever threw was for the Bank 1 cam sensor, replaced it. Later on, code threw for Bank 2 cam sensor, replaced it. It hit 90k miles, so I replaced the spark plugs (not knowing when the last time they were replaced) with NGK Iridiums. Upon doing the plugs, cylinder 2's coil pack would not seat properly/'click'. Replaced that coil pack. Also, cylinder 6's spark plug tube had oil in it (valve cover gasket, I assume). Still haven't done the valve cover gasket but took out any/all oil that was in there and finished the job. That same night, car ran perfectly. Better than it ever has. Next day, back to the same thing, with a SES/CEL back on. Read codes; P0102 (Mass or Volume Air Flow A Circuit Low Input), P0301 (Cylinder 1 Misfire Detected), C1109 (Battery Voltage Abnormal, code has been thrown previously) and C1130 (Engine Signal 1). Spent the ridiculous amount on a new MAF sensor as well as a new coil pack in hopes that (since the plugs are new) a coil pack should fix the said misfire, and of course the night I buy it all, the light turns off. Haven't put the coil pack in, but the new MAF sensor has done nothing except throw the light back on and cause the car to run just as bad if not worse. Went to read the codes again today and it's now throwing P1084 (Exhaust Valve Timing Circuit Bank 2).

Any help is appreciated. I've searched and searched and searched throughout the forums and figured I would just write up one long post and see what happens. Thanks for your time!

 

Has it been raining? I would check the ipdm. Behind the battery, look for corrosion on the connectors. Any moisture signs. The oil in the valve cover will cause misfires and rough engine idle. Have you done the ecm, air idle, throttle body resets? Have you disconnected the negative terminal to reset the computer codes? Anyways I'd check that stuff. Our cars are known to have leaks into the ipdm. My car was missing the stock cover.. (in portland) and dumped water all over the ipdm and fried my computer.. previous days it threw a lot of random codes. Then died. 1500$ later, New ipdm and used ecm, car is running perfectly again.