Hesitation around 3500-4500 rpm

[jonny35]

I have a 2003 Nissan 350z with 6 speed manual transmission with a bad hesitation problem at 3500-4500rpm...I done everything to this vehicle to figure out whats the problem... I have replaced and tested many items on this vehicle and still no positive outcome...Can someone please help me figure out the problem that i have with my 350z...????confused???

Items replaced and tested within the last 6 months...

1- MAF- normal reading tested good.
2- Fuel Pump- same tested good.
3- both fuel preasure regulators.
4- Throttle Body
5- New Berks Catalyct Converters.
6- Motordyne Plenum Spacer.
7- Injen Cold Air Intake.
8- Factory Spark Plugs.
9- Fuel Injectors Cleaner + Induction on Injectors.
10- New Accelarator Pedal.
11- Done all the relearn procedures for Idle,Pedal,Throttle,and ECM.
12- Computer Temp Sensor.

The car has 65,000 miles on it...it has never had a check engine light and it has never gone on...and in cold start the car seem to not have any power until it gets to its normal operating temp...Once its in the normal operating temp then thats when it starts the hesitation and bucking at 3500-4500rpm...So please can anyone give me an idea what else i can do to figure out this problem....???Confused???

[AZ350Z]

Could be a couple things...

1st, try another MAF. Borrow one from another car and see if it fixes the problem.

2nd Cam position sensors...this should throw a code, but doesnt always.

Let us know what you find out.

[jonny35]

thanx for the info AZ350Z...but the MAF has been replaced three time already and the last one was just put in about a month ago and still the same problem persist...but i will try changing the cam sensor...but since ive owned the 350z the light for CEL has never been on and i always check to see if there's a code stored in memory...and it's always clear of any codes.I have owned the car now for two years.I will let you know if thers any changes with the new cam sensors.. thanx

[dasoupdude]

Whens the last time you replaced the clutch in your car?

[jonny35]

hey AZ350Z....the cam sensors did not fix the problems...can you think anything else that can be my problem...thanx jonny

[jonny35]

Hey dasoupdude....i just took the clutch apart this weeknd and it's very low so i think its time to change it....plus i think it also slipping...thanks...if ill let you know whats the outcome when i change it this weeknd.

[dasoupdude]

Mines doin the same, its going to be replaced sometime this month.

[BusyBadger]

Mines doin the same, its going to be replaced sometime this month.

Whatcha going with?

[dasoupdude]

some JWT cluctch and flywheel combo deal i found, that along with a 3.9 FD and quaife 1.5

..and maybe an osiris tune..

[dasoupdude]

scratch that, i opted for 4.08. im never f/i this car anyway.

[AZ350Z]

Nice move...you will love the 4.08's

[dasoupdude]

I sure hope so, i really wanted the 3.9s but they weren't in stock..like anywhere lol