Hitting a Rev limiter at 4.5k
 

Hello, hoping someone can help me out and figure out what the problem is…
Recently my 09 Base 370z started acting funky, I can hard accelerate perfectly fine until it hits 4.5k - 5.5k RPMS before acting like it’s bouncing off a redline…
Then if I manual shift it once it starts bouncing it does a pop like as if it’s tuned but it is not.
I just put another used fuel pump in to see if it would fix the problem and it didn’t, it only fixed my faulty fuel gauge issue from the bad fuel sensor.
One thing I noticed is when I disconnect my battery and let the ECU reset and reconnect it, it runs perfectly fine… I can go all the way to the actual redline no problem. I can drive it for about an hour before it starts acting up again.
I have a Tomei exhaust but it is missing a gasket as I thought I lost it so I put it together just like that until I could get a new gasket… could that be an issue?
I thought about cleaning the MAF sensor, throttle body, injectors or maybe the spark plugs aren’t giving enough spark as I haven’t replaced them since I got the car and it’s used with 89k miles now 112k. I just need someone’s opinion on what it could be

Thanks for reading.

So I’ve encountered this exact problem a multitude of times on my 2009 Base. The issue was the gas cap seal was shot. I either didn’t tighten down enough a few times and it would cause this and the last time I just replaced my entire gas gap with a brand new seal. Haven’t had it occur again.

Are you going into limp mode? If so and if you are WOT but the rpm's slowly rise and up to a certain point, try cleaning out the MAF and TB's. Do all proper resets afterwards and see if this fixes it.

So I don’t think I’m going into limp mode and I checked my gas cap seal and it looks pretty good… would the seal where the fuel pump sits cause the same problem if not seated properly?

When you mentioned the RPM's bouncing at around 4-4.5K, does it take a while to get to that range? Does the car feel sluggish/hesitant on getting up to speed even if flooring the gas?

I notice it’s just a tad bit slower getting up to those rpm’s before it starts bouncing but not enough to say it’s struggling… maybe just a little power loss compared to when the car was running normal

Side note: every time I test it I always do it wide open throttle

Strange every time I’ve had that exact thing happen it’s always been I didn’t tighten my gas cap down enough lol.