I cannot figure this out

SouthArk370Z

As has been mentioned, there are soooo many variables that could affect power output. Without a baseline log to compare current values to, everything is just a guess.

There's always the possibility that a sensor has messed up and the engine is running leaner or richer than before. Might be a good idea to check AFRs, &c.

__________________
Steering Lock Links - Search The370Z Bookmarklet - FSM @ NICOclub
Mankind has progressed past the need for war but we haven't evolved that far. - NachoMahma

smoothtransit

Yeah that is what is making this so frustrating for me. I went ahead and cleaned the MAF sensors (Although they were pristine). I'm not sure if getting a mechanical inspection would be worth it or to go ahead and try to do some dyno tests. Either way im afraid it will be more money and trouble than whats its worth.

zefaulter

I'd suggest an ECU reset if it ever felt slow again

smoothtransit

I actually did do this a few times.

Update: So I took it to Nissan and had them do a full inspection. Since the car was not having the intermittent issue at the time they could not find a locate a direct cause. The head mechanic did however mention that he had one car have this issue before and eventually they located the issue: bad fuel injectors. They also mentioned that there was a misfire code, although i did not have a misfire issue, which would hint that the fuels injectors are indeed the source of the issue.

Anyone have any suggestions on replacing those?

DOOMMONKEY777

Well i have had this issue for some time my self and i finally figured it out,

what has happened to me is that my O2 sensor on Bank2 gives High voltage on cold start 2.59v is hella high, compared that its suposto give 0.1-0.9v or so during its normal operation, witch triggers more fuel adjustments to bank 2, now its not hitting 14.7:1 but more like 11s:1 ratio on one bank.

now this does not stay like that for too long about 6 min until the sensor reaches to some temp point and goes to its normal operating voltage, this made it hard to catch since i warm the car up every cold start.

only one time the code P0158 popped recently when i was running late for work and didnt warm my car up, which caused me to record my perimeters to see wft is going on on cold starts.

GL OP i hope this helps.

__________________
Kids don't do Drugs, Drugs are bad, so let the professional druggies do Drugs for you. 537whp/496lb/tq@8-9PSI 93 octane

Jordo!

Is it under warranty? Just have new ones installed.

If not, you'll need to send them out for testing if you can't figure out which one is running lean via spark plug inspection. Make sure it isn't just a bad (fouled or corroded) plug or damaged coilpack too.

Or you could try an injector cleaning service. As in pressurized special solvent cleaning, directly pumped into fuel rail, not just a fuel additive.

__________________
Enjoy it. Destroy it.