Ok guys,
I DO NOT expect this kind of problem from a Flagship. I can't believe I'm saying this, but I now know why people go German.

Ok, here is the symptom.

1) I start out in 1st gear as usual. I would casually wind out 1st gear to about 4000 and shift to 2nd.

2) I've just shifted to 2nd and let the clutch out. Now, I would step on the gas and give it about 75% throttle. The rpm will start to climb, and suddenly, when it reaches about 3000, the engine hesitates
and looses power suddenly.

3) The rpms will go up from there on, but not as quickly as it should given the amount of throttle I'm giving. (keep in mind that unless the clutch is slipping, how fast the rpm goes up is how fast the car acclerates)

And when it does this, I hear something from the engine bay. It sounds kinda like a loose heat shield. Something goes put-put-put.

What the #@#$ is wrong with my Maxima?

For you 5 speed guys, you know how hard the Maxima pulls in 2nd
after redlining 1st. When this happens to me, 2nd gear feels like 3rd.

It doesn't do this all time, only about 30% of the time.

What do you all think is causing this? Leaking y-pipe? knocking? what?

 

My 2k2 6-speed does something similar, and others with 2k2's said the same thing. For a 2k though I though someone said there was a TSB or recall for the problem you are describing. Some sort of fuel delivery problem.

 

My car has been doing that since 30,000 miles and I'm now at 53,000 and guess what the dealer says every time I take it in, "can not reproduce the problem".

 

If that's the answer the dealer keeps giving you, can you offer to ride along with the technician, or perhaps take the tech along and you drive?

 

sounds like your car may be pinging.... hence the power loss and the noise from the engine bay. You could have bad ignition coils... ther is a TSB on them