Tyler_Canada said:
There is a prototype for the '03 Murano that can be purchased from TechnoSquare. It is not available to the public as there are questions about the CVT longevity, so they didn't follow through and release it for multiple years, etc.
The features are:
- Rev limit increased to 7100 from 6600
- Speed limiter removed
- Ignition timing map adjusted to take advantage of higher octane
- Fuel map adjusted. Nissans run overly rich above 5000 RPM to reduce power so people don't bump the rev limiter
- Drive by wire adjustment. Nissans with the electronic throttle have the throttle closed up to 20% as you near the rev limit so people don't bump the rev limiter.
- Feedback system reduced. Nissans have a feedback system that will notice airflow improvements such as intakes and exhausts, and reduce timing to keep the horsepower the same as stock. This has been all but disabled.
I'm not sure if the electronic throttle closes in the Murano, as the CVT behaviour should make it almost impossible to bump the rev limiter, but the fuel map adjustment to lean out the top end will actually improve mileage slightly under WOT conditions. The fuel map has been tweaked to give a more consistent 12.5:1 ratio, whereas the stock system varies quite a bit and near redline gets as bad as 10.5:1.
The fuel dumping under high load is not to prevent reaching the rev limiter. It is done to keep the catalytic converter temps down to extend their service life.
It is true that the overly rich mixture kills power, but it does increase longevity in a stock vehicle.
I own a performance business geared toward Toyota trucks and we have a full line of engine management and fuel delivery upgrades for when these engines are converted to forced induction. We are also coming out with a full line of turbo kits.
For N/A vehicles we sell a box that allows you to remap the signal from the MAF sensor and allows you to control the mixture in OPEN LOOP operation. We find when the engines are leaned down from 10.5:1 AFR to around 12.0 AFR we consistantly see 10-20 HP gain on an otherwise stock engine. Now when you couple this with devices that increase flow like cat deletion, performance exhaust and a smartly designed intake system the results can be much more.
Now I have not done this on my wife's Murano, she won't let me... But the concept is the same.
I have not tested compatability with Nissan products, but the one we have for the Toyotas sells for between $200-250 depending on version and it has the highest map resolution of any end user tunable calibration units on the market. The beuty of this approach is that it is end user tunable by YOU unlike some of the otehr stuff on the market. This way you can always retune for best power every time you install a new mod instead of having to pay someone else to do it for you and pay $800-1000 everytime.
We have also had a break through in CLOSED LOOP mixture control. We have found a way to adjust the fuel mixture in closed loop and that product should be ready for production very soon, but again I have no idea on compatability with Nissan products.
One thing I would caution you on with folks that want to sell you a ECU reflash program. Up until recently Asian ECUs were not reflashable. Only in the last 4 years or so has this been possible. In most cases you are getting a cookie cutter program that is not specific to YOUR vehicle. A custom tune on YOUR vehicle will always be best. The other problem with ECU reflashes is that anytime your vehicle goes to the dealer for ANY kind of service they may load an updated calibration without you knowing about it and this will wipe out your expensive aftermarket reflash program.
If anyone buys an ECU reflash be certain that you get what you are paying for. Do before and after dyno tests and check your WOT fuel mix before and after. There are a lot of companies out there that simply take your money and put a sticker on the box and DO NOTHING for you. These are called sticker tuners and they are EVERYWHERE.
Gadget