Hello,

I recently took my 2006 Nissan 350Z into the shop to get it looked over after a road trip but it doesn't drive the same after doing so. Now, when I shift up or put the gas on quickly, the RPMs shoot up then come back down, then gradually climb back up as the car accelerates. Before, the RPMs would just steadily climb as the car accelerates as it should.

Here is a list of parts replaced:
1) oil filter
2) oil drain plug
3) camshaft position sensor
4) valve cover without gasket
5) valve cover gasket
6) intake plenum gasket

Again, the issue is the engine revs up sharply then comes down, then steadily climbs back up when accelerating or shifting up.

Does anyone have any ideas on what the problem might be?

Thanks!

 

slipping clutch

 

^^^

 

Can be slipping clutch, yes. If you hear the engine tone also going up meaning engine actual RPM matches rev counter than probably really is a slipping clutch.
But, since you have replaced CPS there's a possibility of sensor malfunction. When CKP (crankshaft position sensor) is faulty you can get RPM needle doing crazy stuff and engine stuttering. Similar can happen when CPS is going bad.
Also - intake plenum gasket and other gaskets requiring taking apart the intake system - if TB was cleaned you can have issue there as 350Z's TB valves are notorious for going crazy when you fiddle with the valve - moving it by hand. Though if your idle is OK this isn't the issue than.


If your clutch is slipping replace it as soon as possible. Driving with the slipping clutch will destroy you flywheel.

 

Shop had some fun in your z and toasted the clutch or installed some bad sensors. Just some possibilities not saying its true, maybe. I don't trust shops.