Thread: Tuning for Gas Mileage

Where do you guys keep your tire PSI at?

I haven't checked mine in a bit, but when I go on a road trip at 35-40. Usually just 35 to be safe if I have to drive on a hot day.

This is for front and back, car seems to drive much smoother too

Here is the latest update on Fuel Map tuning, with no timing udpates. Now I do realize I don't have a good base to start with. But that will change when I go on the trip next week, I will have more constant numbers.

Miles Driven: 19.0
Gallons Fueled Up: 1.197
MPG: 15.87

All City driving, stop and go, stop lights. Stepped on the gas about 3-4 times, not always to red. Other then that regular driving.

This is exactly what Ben was saying, fuel maps alone don't seem to do the trick. It doesn't help that while in closed loop, the wideband didn't show numbers that were actually on the fuel map.

I think for this to make a difference, I may need to set the fuel maps to 17:1 A/F and then it should probably be around 15-16 in real life.

the nissan ecu isnt going to let you run leaner than 14.7 in closed loop unless you can some how trick it with o2 sensor voltage manipulation. with my b13 i used values that would be 18.0 and down to 13.0 afr and still got mid 14's. this is the limit of the narrow band o2 sensor. you are going to have to tune timing with the stock ecu to try and get better mpg. or even better yet your right foot and timing lol.

Yeah that's what it's beginning to look like. I might just install back my burned up O2 sensor, since it allowed me to achieve 16's.

The right foot, eh that's a hard one. The idea here is to get the best possible MPG while leaving the car fun to drive, and still driving it like fun. It wont get me 50mpg, but getting it up to 35mpg highway from 27 would definitely be nice.

My A/F ratio is much lower than yours (no exact number but it is rich at all rpms) but my timing map is great because I get about 20mpg mixed city/highway, romping on the throttle often. My trip mileage is about 25-28mpg. Setup is in my sig. I can send you my tune to look at if you want.

Sure! Your setup looks fairly similar to mine, sending you PM with email.

Here is another quote that further proves BenFenner's theory as being correct.

Fuel saving - a professional engineer's view




Another link: http://www.fuelsaving.info/vehicle.htm

what parameters are you using to tune your timing? knock sensor? what are you using to gauge a threshold for timing?

Nothing yet, I can try using NissTune, I think I saw a feature for knock detection, if it even works on our cars.

I'm not going to do anything crazy, I'm thinking a 2 degree advance across the map, and seeing if it does better then 15mpg city haha.

Now before I installed the Fidanza flywheel, 6 puck clutch, stopped using MT90 (didn't have time to wait for it), and went blow through, I think I used to get 18-20 city...

Highway stayed the same original turbo setup vs what I currently have. In fact I think highway went up 1 mpg