I've tried driving it nice for a week, (hard to do mind you) with almost same result, I got a bit less than 18MPG. What mods do you have on?

I've got 37k on it now, just changed to a k&n filter panel a few days ago. should wait how long before noticing anything?

I was also thinking of resetting the ECU/TCUs maybe somehting screwed up in the averaging and some point... I do notice the tranny takes a while to change from reverse to drive on humid days.

for those interested here's the procedures taken from
http://www.automotiveforums.com/t275...th_a_g35_.html

You can manually 'reset' the learning curve of the ECU if you want by following these procedures:


Infiniti G35 ECU Resetting Procedures

NOTE: Please read all instructions and be familiar with them before any attempts. Timing is extremely critical. If it is not done within the specified time, the ECU will not reset and the Check Engine Light (CEL) will continue to remain ON. A stopwatch or an analog clock with a second’s hand is advisable.


Basic ECU Reset (from http://www.technosquareinc.com/350reset.htm)

Operation Procedure:
1. Confirm that accelerator pedal is fully released, turn ignition switch “ON” (NOT start) and wait 3 seconds.
2. Repeat the following steps (2a and 2b) procedures quickly five times within 5 seconds.
2a. Fully depress the accelerator pedal (HARD).
2b. Fully release the accelerator pedal.
3. Wait 7 seconds, fully depress the accelerator pedal and keep it for approx. 10 seconds until the CEL starts blinking.
4. Fully release the accelerator pedal (while the CEL is still blinking)
5. Wait about 10 seconds.
6. Fully depress the accelerator pedal and keep it for more than 10 seconds.
7. Fully release the accelerator pedal (The CEL light will continue to blink).
8. Turn ignition switch to “OFF” position and now you can start the car. The CEL light should be gone. If the CEL light continues to remain ON, repeat the above steps. Remember, accurate timing is EXTREMELY critical to resetting the ECU. You may even need someone's help to do this correctly.


Note: The following reset procedures are directly from the 2004 G35 Sedan Service Manual.


Accelerator Pedal Released Position Learning

Description:
Accelerator Pedal Released Position Learning is an operation to learn the fully released position of the accelerator pedal by monitoring the accelerator pedal position sensor output signal. It must be performed each time harness connector of accelerator pedal position sensor or ECM is disconnected.

Operation Procedure:
1. Make sure that accelerator pedal is fully released.
2. Turn ignition switch ON and wait at least 2 seconds.
3. Turn ignition switch OFF and wait at least 10 seconds.
4. Turn ignition switch ON and wait at least 2 seconds.
5. Turn ignition switch OFF and wait at least 10 seconds.


Throttle Valve Closed Position Learning

Description:
Throttle Valve Closed Position Learning is an operation to learn the fully closed position of the throttle valve by monitoring the throttle position sensor output signal. It must be performed each time harness connector of electric throttle control actuator or ECM is disconnected.

Operation Procedure:
1. Make sure that accelerator pedal is fully released.
2. Turn ignition switch ON.
3. Turn ignition switch OFF and wait at least 10 seconds.
Make sure that throttle valve moves during above 10 seconds by confirming the operating sound.


Idle Air Volume Learning

Description:
Idle Air Volume Learning is an operation to learn the idle air volume that keeps each engine within the specific range. It must be performed each time electric throttle control actuator or ECM is replaced, or if idle speed or ignition timing is out of specification.

Preparation:
Before performing Idle Air Volume Learning, make sure that all of the following conditions are satisfied. Learning will be cancelled if any of the following conditions are missed for even a moment.

- Battery voltage: More than 12.9V (At idle)
- Engine coolant temperature: 70 - 100 Degrees C (158 – 212 Degrees F)
- PNP switch: ON (5AT only) **or** Shifter: Neutral w/ Clutch: IN (6MT only)
- Electric load switch: OFF (Air conditioner, rear window defogger, headlamps. Note: on vehicles equipped with daytime light systems, if the parking brake is applied before the engine is started, the headlamps will not be illuminated.)
- Steering wheel: Neutral (Straight-ahead position)
- Vehicle speed: Stopped
- Transmission: Warmed-up (For A/T models, drive vehicle for 10 minutes.)

Operation Procedure:
1. Perform "Accelerator Pedal Released Position Learning"
2. Perform "Throttle Valve Closed Position Learning"
3. Start engine and warm it up to normal operating temperature.
4. Check that all items listed under the topic PREPARATION (previously mentioned) are in good order.
5. Turn ignition switch OFF and wait at least 10 seconds.
6. Confirm that accelerator pedal is fully released, turn ignition switch ON and wait 3 seconds.
7. Repeat the following procedure quickly five times within 5 seconds:
7a. Fully depress the accelerator pedal.
7b. Fully release the accelerator pedal.
8. Wait 7 seconds, fully depress the accelerator pedal and keep it for approx. 20 seconds until the MIL stops blinking and turned ON.
9. Fully release the accelerator pedal within 3 seconds after the MIL turned ON.
10. Start engine and let it idle.
11. Wait 20 seconds.
12. Rev up the engine two or three times and make sure that idle speed and ignition timing are within the specifications:

Idle speed A/T: 650rpm, + or - 50 rpm (in P or N position)
Idle speed M/T: 650rpm, + or - 50 rpm (in N position)
Ignition timing A/T: 15 Degrees BTDC, + or – 5 Degrees BTDC (in P or N position)
Ignition timing M/T: 15 Degrees BTDC, + or – 5 Degrees BTDC (in N position)

13. If idle speed and ignition timing are not within the specification, Idle Air Volume Learning will not be carried out successfully. If idle speed and ignition timing are within the specification and Idle Air Volume Learning cannot be performed successfully, find the cause of the incident by referring to the following Diagnostic Procedure:

1. Check that throttle valve is fully closed.
2. Check PCV valve operation.
3. Check that downstream of throttle valve is free from air leakage.
4. When the above three items check out OK, engine component parts and their installation condition are questionable.
5. If any of the following conditions occur after the engine has started, eliminate the cause of the incident and perform Idle Air Volume Learning all over again:

- Engine stalls.
- Erroneous idle.

Alternatively, you can disconnect the battery cables for 12 hours but, be advised, you will lose all programmed info such as radio and NAV pre-sets. If you successfully accomplish the ECU reset procedures above and it does not make a noticable improvement in a seemingly sluggish g35, head to the dealer for a diagnostics check.

 

My 5AT gets 19-20mpg in 100% city and 26-27mpg on the highway and I don't reset the ECU. Same goes for the track. IMO, reseting the ECU to gain power or MPG is a farce and really makes no sense when you consider the fact the car will actually run richer after a reset. That goes completely against the notion of better MPGs or power.

 

People don't realize that the engine MUST run [idle and cruise] extremely close to 14.7 AF for the cats to actually work and pass emissions. Just an AF deviation of +-3% will throw the whole system way off. Nitric oxide emissions go thru the roof either side of the EXACT optimum point.

Avoid ethanolized gasoline as the lower average BTU will result in a 3-4% decrease in MPG [or worse depending upon water content]! Ethanolized like any oxygenates can fool the O2/ecu into running 3% richer than actuality...extra fuel to make up for extra oxygen.......this is in addition to the above power loss from lower heat of combustion......at worst it is additive resulting in a 6-7% MPG decrease depending on some ecu program variables and ambient temperature. It will vary slightly car to car .

 

now that's something i didn't know... the gas station chain I sometimes fillup from advertise a 10% ethanol content to be called "a environmentally consious company"... but now come to think of it, they're selling at the same price as other gas stations yet they're giving us 10% less gas!! it's either we're being ripped off by that chain (petrocan for those canuks amongs you) or the competition are also putting ethanol but are not telling us.

Q45, knowing our ethanol content can we change ecu programming to take in consideration the ethanol content? this way I'll always tank from the same gas station that guarantees the ethanol content.

 

Petro-Canada doesn't put ethanol in their gasoline, except as follows:

"Oxygenated gasoline (ethanol blend gasoline, gasohol, or gasoline with ethyl alcohol)
— available at some stations in Montreal (in SuperClean* 94), Saskatchewan and
at a bulk plant in the London, Ont. area (for farm customers)."

Nobody can sell ethanol in their gas without telling you.

 

...if you don't already have an auto, and do alot of freeway driving, a 3.3 pumpkin helps.

 

i don't get it.

 

The ecu programming is factory calibrated for conventional gasoline without oxygenates of any type MTBE or Ethanol, since only 30% of US usage was oxygenates when the vehicle was designed.

US has millions of bushels of last years corn rotting in storage it must be used for something.

All about a secret indirect Farm subsidy to support corn prices.
http://futures.tradingcharts.com/chart/CN/M

 

The 3.3 final drive from an AT will put you at lower rpms at the same speed vs. a 6mt. So instead of over ~3k at 80mph, you'll be at ~2.7k'ish at 80mph. Helps on long drives. If you already have an auto....nvm. Umm...an alignment might help...

 

If you could lower the cruise rpms of an engine by 10% you might at most save 50-75 gallons per year.........it would take 2-4 years to wash with used acquistion and installation costs.

The problem is pulling an incline in 5th/6th with AC on and a full load of passengers.........if you always drive alone or don't weigh too much or don't carry anything in trunk. You can always downshift one gear if you have a load.

 

here's an update for those still interested.

I've reset my ecu as per the instructions above and I've been babying my car for the last 500km as to get the "learning curve" setup for a more conservative driver i've noticed few things:

1. my NAV mpg value is closer to the correct value, before it used to be 2MPG higher (1 liter/100km lower) than the real value.
2. Gear shifts are more regular at low speeds
3. My gas pin isn't jumpy, used to change by as much as 2ticks on the drive home (20km)
4. improved MPG. right now its around 22MPG. where I was getting 16-17MPG (13.5-14l/100km for the metric folk) before.
5. yesturday at the pump I filled 10.1liters for 105km thats 24MPG, thats after an hour heavy traffic driving home

now the mpg could be because I'm driving more carefully, but I've tried that before and only got upto 18MPG. My NAV is showing 10.2 - 10.7l/100km which it never did before. I've also changed to a k&n filter a couple of weeks back, that might also amount to something...

before anyone starts calling bull****... I have done this myself and noticed the difference on my own car.

well hope this helps someone out there. I know a few members are getting weird driving/mpg ratios.