This might be a silly question, but I've noticed that in 3rd gear when I try almost flooring the gas at around 3K RPM's, I get barely anymore speed out of the wheels. Anyone have any clue why? I don't want to start thinking it's a performance issue and not a "I'm not accelerating at a good gear/RPM range" which is probably what it is, but I'm not sure.

 

5AT or 6MT?

 

If 5AT, does the car downshift to a lower gear? OR stay in the same gear?

 

I have a sluggish 3rd gear pull too drop to 2nd if you can and you should be good. I have test pipes too so i lost the lower end torque and gained more up on the top.

 

2nd is great, pulls really well throughout the RPM band. Any gear higher just pulls terribly below 3k RPM. It's a 6MT, forgot to mention that haha.

 

^ common problem with G35 its the gear ratios-- You may have heard terms like rear axle ratio or final drive ratio. These refer to the gear ratio in the differential. If the final drive ratio is 4.10, then the ring gear has 4.10 times as many teeth as the input pinion gear .... Little to nothing you can do about it unless you upgrade the transmission.

 

2nd gears ratio is 2.3248 meaning the fastest increase in speed will be first gear im sure you already deciphered that much, so if you do an upgrade increase both 3rd and 4th gear to get down more torque.

 

But once it hits 3K it tends ot perk up?

I've never really found the G35 to pull hard at low RPM's. I know guys say it's a torquey motor, but i've always been used to V8's with 250 ft-lbs of torque at idle. The G35 i felt always needed to be higher in the RPM's to really get moving. If i find myself under 3K and the 5AT doesn't downshift for some reason (ie only pressing the gas 3/4 of the way) then it's very sluggish up until 3.5K-4K. If i had a 6MT, i'd probably downshift at 3000RPM if i wanted to go WOT

 

Lol bro V8 vs VQ V6 your going to see a huge difference in acceleration. Over 3k rpm the car already has full traction and is moving so you'll feel more of a pickup for sure. The 5At shifts depending on how far the gas pedal is depressed so if it doesnt down shift stomp on it and it will. But I was just making reference to 3rd gear, its quite slow due to the ratio set up.

 

I'm not sure if what's happening to me is this situation that happened to you.
but sometimes when I turn my car on and it's not fly warmed up. and I take off. I get to the stop sign down my street then I proceed to go and like there is lag in acceleration like the engine doesn't react what the gas pedal tells it for a split second then the engine reacts and it goes into get and jerks real nasty. I don't floor it when I feel that nothing is reacting to the gas pedal, so I don think the "jerking" is dropping gears. but I may be wrong..
is this the same problem?

 

That sounds like it's not "normal" and more of a situation with how the cars running.

Any check engine light on, or when was the last time basic tune-up items like plugs, air filter, MAF cleaning, etc were done?

 

Lots of these issues can all be fixed with bolt on's and a tune =) lol

 

Thats not true gear ratios will not change by bolt on's

 

yes. it is not normal. No check engine light, and I'm not sure about the about the last time the plugs were changed...
according to the last owner, the trans fluid was changed 4k miles ago.
the air filter is dirty as hell though. I just ordered and eBay intake.
and while replacing it I am going to clean the throttle body. because a dirty TB is causing the bog when starting problem.

 

The dirty air filter alone could be the issue. Depends on how dirty we are talking.

Go to radio shack and grab some electronics cleaner and clean the MAF. Do an ECU reset as well (search on the forum for the method) and go from there. Car might need spark plugs too depending on how many miles you have