350ZNY

The past few weeks my car no longer has the power it had under 4K RPM. I used to be able to have the car in 1st gear and at 2K RPM floor it and it would really take off, now it just bogs in both 1st and second gear until I hit 4K RPM. After 4K RPM the car feels the same as it always has. I have 13K miles on my 03 Base Z.

Does anyone have any ideas? The clutch doesn't seem to be slipping. Jason at performance said maybe the Mass Airflow Sensor. The car almost seems to take off faster if i have the AC on which is weird. Please help, I am taking it to the dealer Wednesday.

One other thing the car is completely stock.

Thanks,

Pete

DayBlueZ

iTrader: (13)

Reset the ECU. Before you go to bed, unhook the battery and let it sit for 12 hours then hook it back up. See if that helps.
Are any dash lights on?

350ZNY

DayBlueZ,

No dash lights on at all. I will reset the ECU tonight. The only other thing I can think is the clutch but it doesn't seem to slip. The revs never jump up.

Thanks for the reply.

jcpeyton

iTrader: (1)

Does the ecu reset really require 12 hours? Should both positive and negative terminals be disconnected? Sorry if this sounds like a stupid question.
Not to hijack the thread, but my KJR crank pulley goes in Wednesday. I have nismo exhaust and Stillen cai. I've seen on other threads that the ecu can take 5-6 days to reset itself w/out a battery disconnect.
Should I disconnect for 12 hrs. after the pulley is installed and I drive the car home?

zzzya

iTrader: (2)

The "feel" meter is pretty tough to judge. You could just be getting used to the car. I have had different ECU reflashes that all "felt" good, but out on the track it was a completely different story!! If you have any other tests to tell if the performance has deteriorated it may give this more credibility. You should follow the ECU resetting instructions to reset the ECU, not disconnecting the battery. Also, If you have disconnected the battery in the past you may need to perform the TB resetting instructions as well. You can find the info here:

http://www.technosquareinc.com/350reset.htm

A stopwatch, or watch with second hand, is helpful as timing is everything. Another thing to consider are the spark plugs. Without an aftermarket plenum to even out the A/F ratios to all cylinders, you could have some fouled up plugs in the front cylinders.

350ZNY

zzya,

I know the feel meter is pretty tough to judge. What made me notice it was I had my car in for service for the front tires to be replaced and the window drop problem. When I picked up the car in the afternoon it did not feel the same in 1st and 2nd at the lower RPM's. It just doesn't pull the same. I can't think of anything that the dealer did to effect performance.

If it was the MAF would the check engine light be on?

Are the front plugs hard to get to? I am wondering if the plugs are fouled like you said.

The car goes to the dealer tomorrow. I just want to have an idea of what they should look for. They don't seem to be the smartest.

Thanks.

350Zenophile

iTrader: (20)

This is a stretch, and I don't know if the base model even comes with Traction Control, but I do recall reading something about having larger tires on the front vs. the back causing the computer to think there is a "slip" condition and cutting power.

If you have Traction Control and you did not replace the back tires at the same time, this may be the problem. Do you notice any lights pop on when the car cuts power?

350ZNY

No traction control on the base model. I was thinking the same thing, how could the new tires affect the performance.

350ZNY

Took the car to the dealer, they found nothing wrong. They scanned it and found everything to be normal.

Any other ideas? What can I do to improve performance? I am stock. Crawford plenum? Exhaust?

350Zenophile

iTrader: (20)

Why would you want to modify a car if you think something is wrong with it? or are you now convinced it's all psychological?

350ZNY

350Zenophile,

I am thinking it is psychlogical. On the way home from the dealer I stopped at Infiniti and drove a 05 G35 coupe auto. I turned traction control off and used the manual shift. I know it is an auto but it didn't pull like my car. I am going to drive a 6 speed G35 coupe tomorrow or Saturday. That should be an even better comparison.

I didn't drive my Z all winter and last summer I only drove it a couple times a week. Since April it has been my everyday driver. It could be like zzzya said, I am just getting used to the car. If so, I need to make it faster.

Bran_BranZ33

have you driven any faster cars recently? i drove in a friends Z06 and my car felt slow for weeks until i got use to it... just a thought