Jdeaton01

I just bought my first z this past weekend. Its an 04 350 z roadster automatic. Whenever I give it gas like when im passing someone it isn't dropping into a different gear.

Any ideas?

icer5160

iTrader: (4)

Could be low on ATF. Check your levels, I highly recommend a drain and fill service (not a flush), maintenance history on anything Automatic is usually a big unknown, so it's worth doing a full fluid service for the entire vehicle unless you have records/receipts showing it . How many miles on it?

Also, have you tried scanning for any active or pending DTCs?
Cheers,
-Icer

Jdeaton01

The car has 110 xxx. I had another issue with a misfire when i was almost home with the car. Ran great before that. Onky codes i could ever get it to read are .p0165 and p1564. It also read p0304 briefly, i swapped coils to see if issue would follow and the misfire cleared up.
They would clear themselves and come back
now the car is running fine again on its own.
Its just like it doesnt drop into a "passing gear" unless i do it manually

icer5160

iTrader: (4)

I would work on resolving the P0165 code. A lazy O2 sensor could cause poor running conditions, everything from lack of power to potentially causing limp mode to trigger. A misfire condition could also cause this. It's possible the PCM is refusing to downshift (stress the engine & trans) since it's detecting an active fault condition. As you stated, this can be overridden through the Manual or Sport mode bump shift option. If the misfire comes back, consider replacing all the coil packs with OEM units, you're also at a mileage point where spark plugs should be replaced if not already done so (use the OEM recommended NGKs).

Once you have the engine in a healthy/happy state, see if the problem persists. If it does, then I recommend servicing the transmission. There's always a chance for mechanical failure with a higher mileage automatic, but RWD Nissan Automatics have been decent (non-CVTs that is), assuming they have been properly maintained.
Good Luck!
-Icer