February 11, 2008 at 1:40 am #510
Trying to poke around and increase performance a bit. anyone seen a website or source that has info on how to change the ECU for increased HP to the wheels. I found some for the 350Z but not the Quest. I have a 07 model and i know if I can locate the sofeware and adapter I can change the engine performance profile to up Horse power. Tweaking the bottom and midrange power will increase MPG’s some what.
I am working on changing the air cleaner and snorkle as well as exhaust. at 18.3 MPG it is not fun as a daily driver.February 14, 2008 at 3:09 pm #2857
I’m confused. You want to increase horsepower AND fuel economy? I’m assuming you mean decreasing HP (which is just a function of torque) in the low and midrange and increasing it in the top end? I’d advise against it since your torque curve wouldn’t be smooth anymore and your WOT acceleration would feel like an amusement park ride.
And you only get 18.3mpg? Is it all city driving or are you WOT all the way to work? I just drove an 07 last night (65 miles round trip) and got 26mpg.February 15, 2008 at 3:50 pm #2858
Are you really so confused?
We have a 2004 Quest and 18.3mpg is a good average for us. It is most of the time city driving but even with having long trips I hardly ever reach 20mpg.
Last year we drove to South Carolina and we’ve finally seen 23mpg! This was the highest ever!!
And to make sure – I am not cruising around like crazy, because gas mileage is important for me, almost like a sport!February 15, 2008 at 8:19 pm #2859
I have an 05 Quest 3.5S which I drive very carefully and an 18.3 mpg average would be good. Most of my driving is in town and my avg is about 16 mpg – in the summer using AC most of the time it’s more like 15. On long highway trips driving 70-75 mph I get about 21 mpg (if I’m lucky). All my numbers are based on dividing miles driven by actual amount of gas I put in.February 18, 2008 at 8:58 pm #2864
Drove another 07 Quest over the weekend and got 24.6mpg…based on approx 70% highway, 30% city.
SoccerDad, thought more about what you said and talked to the powertrain group. What you’re proposing would probably help fuel economy a little, but the lower torque at the bottom and middle would mean that it would take forever to get to highway speeds.
Of course it’s completely up to you (it’s your van), but I’d say that the several hundred thousand dollars of man-hours that Nissan spent to tune the power is probably a pretty good place to be.February 23, 2008 at 8:48 am #2869
I’d like us to be exact about how we are measuring the fuel consumption and then we can really compare. The computer on my 07SE says that we get about 21 or 22 mpg on hwy and about 18 or 19 around town. I will measure it based on miles traveled / gallons used and report back. One thing I’ve thought about for improving performance (and fuel economy) is deleting the huge muffler that is in the middle of the exhaust. I was shocked when I looked under my quest to see about 20 mufflers and/or cats under there. (OK a slight exaggeration). I was thinking of bypassing and removing the largest one in the middle, which should give the exhaust a straighter shot, and relieve some weight. I don’t deny this seems a little crazy, but I’d like to see what it does.February 25, 2008 at 6:04 pm #2872
Due to the way we fuel and track the fleet vehicles, I’m not able to calculate fuel economy the way you’re proposing, I can only go by the trip computer. It uses the electrical pulse of the injectors to measure fuel used, which is probably more accurate than assuming every fuel pump shuts off at the exact same top-off amount.
As for removing the muffler, I don’t think I can even justify that with a response. You bought the car, you can do to it what you will.February 26, 2008 at 7:27 pm #2876
I did say one of the mufflers, How many does the van need? I see two mufflers under there other than the large one that I would consider removing. The van is perfectly silent. Maybe I would trade improved flow for a bit of noise. It is not a permanent change, so what the heck, I might give it a try. Any other comments / suggestions?
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