I'm a very unhappy right now. I took it pretty easy on my '05 G35 sedan w/5AT until I hit 1000 miles, and then I started progressively getting into it more as I reached 1200 miles. My decision to get this car instead of something else was largely based on the performance. Well, my car is nowhere near as quick as it should be, and a lot slower than the car I test-ragged at the dealer. I timed three 0-60 runs and each was 7.5 secs (a/c off). Isn't this supposed to be a low 6-sec car? Yeah, it's hot outside, but heat won't cost 1.3-1.5 secs in the 1/4 much less in 0-60. Then I noticed that the car is quicker at part throttle than it is at full throttle. Whether in auto or manual mode, and at any RPM. And the car lunges forward a bit as I'm taking my foot *out* of the throttle. It seems that 1/3 to 1/2 throttle is the sweet spot. Gonna talk to the dealer tomorrow, but wanted to see if anyone here has had a similar issue. Anyone?

 

Your car is not even broken in yet and the ECU has to get adjusted to your driving.

 

How are you timing it?

Also give it some more time. 1k aint enough.

 

7.5s vs ~6.0s with a car weighing about 3500 lbs is around a 75-80 hp difference. A tight engine doesn't rob anywhere near that much power, and 1.5s is too big a difference to be a timing error. And the car I test-ragged had similar miles as mine (~25) and it kicked this car's *** big time. After thinking about it for a while, it must be a problem with the throttle position sensor, given that the car pulls harder at part throttle.

 

Running 91+ octane?

 

Did you turn off vdc?

 

The ecu is always adjusting. I find if I drive mellow most of the time that when I punch it, the car doesn't want to give max effort. If I drive it hard for a few runs, then the car responds the next time with great spirit. My advice would be to drive it hard 3 or 4 times over a few days and see if you still experience the same problems. Good luck!

 

Also sounds like you might need to re-calibrate the throttle position sensor... The how-to is around here somewhere if you search for it, or the ECU reset procedure.

 

NEED TIME! Mine responds beautifully.

 

Sounds to me like your throttle position is incorrect. The dealer can readjust that and a few other things for you to regain the missing performance.
C.

 

I bought my '03 Sedan brand new. Like you, I "babied" it for the first couple thousand miles, as I was instructed. However, after 2 years, my G is still a SLUG. I've mentioned this to the dealer several times in the past when I've had other maintenance work done, but they always tell me everythings fine. I've gotten SMOKED by a Hyundai Elantra from a red-light! (NO LIE....obviously i dusted the Hyundai very shortly thereafter.) However, this should not have even been up for debate.

This is the first i've heard of having the throttle re-calibrated. I'm going to contact my dealer about this and pray this works. I'd enjoy my car so much more if I got the same power & response that I get from their loaner g35's! Hate to hear of this happening to someone else, but I've very glad everyone has replied with suggestions on how to correct it. Thanks for your help and keep posting.

*** Another thing....I hear the issue with the ECU constantly adjusting all the time. Why would the Nissan/Infiniti ECU over-compensate so much. I mean it feels like if I do ANY amount of "soft" driving in the city that I should be very careful about any quick merges or lane changes when I hit the highway.

 

Sounds like VDC is getting in the way.
It will cut back the throttle if there is any slip detected.
(you can turn it off.... well almost )

 

It's not gas, ECU adjustments, or VDC. I run 93 octane Chevron, the ECU won't pull out 75 hp (unless there's a major detonation problem), and my car can't spin the tires with or without VDC on. Gonna give the dealer a chance to fix. If they can't, then I'll take it up with Infiniti directly.

Frndlychat, good luck with your '03.

 

1) I must ask how these 0-60 times were achieved. Ricer-Tech (G-tech), stopwatch? Take it to the track to get a real idea of if there's a problem. Timing the car on a back road introduces a ton of basis.

2) The throttle on the 5AT is very touchy. It takes very little throttle to leave a light at a strong pace. It's also much the reason why the 5ATs feel so much quicker around town. There isn't a huge difference in acceleration when going from 1/2 throttle to WOT. It's the way Nissan tuned the throttle by wire. It still didn't stop my car from going 14.4s though.

3) Hot and humid weather inevitably makes cars slower. Car's with relatively high compression ratios tend to be more influenced by the heat because they are more likely to get detonation as temps increase. The hotter and more humid the air, the less dense it is (less oxygen) is available. It's not uncommon for a motor to loose about 10% of it's power on an 85 degree day vs a 50 degree day.

4) Nissan knock sensors have a history of being very sensitive. While you will probably never hear detonation, your G's knock sensor will and it responds instantly. When knock is sensed, the ECU will dial back timing and will richen the fuel mixture. Both of these safegaurds will kill performance.

5) In hot weather (85+ degrees), it's not uncommon for a mid 14 second car to drop to a high 14/ low 15-second car. That's just the way it goes. I've seen this with every car I've owned and raced.

6) Nissan ECUs and pretty much every other ECU on any 95+ OBDII car is constantly adjusting to load and atmospheric conditions. Some ECUs are more touchy than others with the ECUs of higher performance motors leaning on the side of "touchy". The ECU's aren't as smart as people think they are though. The ECU has preprogrammed data tables and it uses the various drivetrain sensors to determine the most efficent and safe tables to choose from. In a way, the ECU is always changing, but it's not as dramatic as people would like to think.

7) Fresh engines typically need about 5000-10000 miles to fully open up. It's not uncommon for a car to drop .2-.4 seconds and gain 2mph in the 1/4 mile simply from breaking in.

8) Spinning the tires is a pretty much meaningless way of basing a car's performance because tires, surface, and atmospheric conditions play a huge roll here. At the track, my G doesn't chirp a tire and that's on crappy Turanzas. On the street in 90 degree weather and with a pretty aggressive 2200-2300rpm launch, the car may or may not spin the tires about 2 to 10 feet. Without stalling the torque converter and just mashing the gas, the car might chirp a tire, but that's it. In 40 degree weather, I can keep the tires spinning through most of first, fishtailing side to side down the street.

 

Stopwatch on level, deserted stretch of highway. Sure, manual timing can be off a tenth or three, but not fifteen (1.5s), and not 3 consecutive times.

My car pulls harder at 1/3-1/2 throttle than it does at WOT.

I'm an experienced drag racer (Mustang Cobras and Z06), so I know what weather does to a car. Heat does not slow a car down by 1.5 seconds in 0-60, which is equivalent to 2.0+ secs in the 1/4.

This could very well be the problem, or part of it. The gas is good, cuz its the same gas I always put in my Z06 (very high compression), and I never had a problem in hot weather.

Granted, but if the mid-14-sec car is running mid to high 16s (see #3), there's a problem.

A tight engine will rob a little power, as will heat and humidity. But it won't slow a 6.0s 0-60 car down to 7.5s.

I agree. I merely reported that VDC was not the issue because my car can't spin the tires.

#2 is all I need to know to be convinced there's a problem.