Good info, Ive been looking around for a focus for the past month or two now. Thats good to see how high mpg you're getting. Are those 100% accurate figures and have you done any mods to it at all? I was looking at the 2.3L with 153hp but they seem too expensive still but I like some of the PZEV 2.0's. Again nice info, were you using the ScanGauge II too? Im hoping to get some stats on our cherokees because every trip to and from school is 100+miles and Id love to save a couple bucks from going from 16-17mpg to ~22 or so. Maybe this trip back tonight I'll try it out at 65mph and fill up before I leave at a mobil station and then see what the changes are when i get to worcester.
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Jeep 4.0 Volumetric Efficiency
- Thread starter BBeach
- Start date
MaXJohnson
NAXJA Forum User
- Location
- The Kansas Rockies
Here's some data from a 18.5 mile loop consisting of about 14 minutes of freeway (in the middle, cruise set at 60MPH) and about 12 minutes city streets. The time segments from each graph match up, so you can overlay or compare data from one graph to the other. Sorry I don't have MAP data. Load is a percent of total power. I don't know if Jeep determines this from maximum engine power, or maximum at the given RPM as the OBDII load parameter is handled differently by different manufacturers. I suspect it's based on maximum engine power. The "hard" and "extreme" acceleration and braking lines are .25 G's for the dotted line and .40 G's for the solid line.czb83 said:
MaXJohnson
NAXJA Forum User
- Location
- The Kansas Rockies
The data is from a 2005 2.0 5spd ZX3. Probably the most fuel efficient version of the Focus (why I bought it). I've had the ScangaugeII permanently installed in the car since last summer, so I have a lot of experience with it. I purposely waited until a trip to western Kansas to run these tests since the Kansas City area isn't flat enough. Each segment is under the same relative conditions and each is averaged over a 5 mile segment to get a stable reading. I've seen slightly better mileage numbers, since these were taken with a bit of cross wind which affects both Cd and frontal area (force vector). In real world driving, I've seen a high of 42MPG and a worst tank of just under 27MPG. On a recent trip across Kansas, through the Rockies to Salt Lake City and back, I averaged 37.+ overall with 2 people and luggage.BBeach said:
Running my 97 XJ on a makeshift 12 mile freeway test loop yesterday and today (using the cruise control), I came up with the following:
55MPH - 22.0MPG
60MPH - 20.6MPG
65MPH - 19.6MPG
This is the same loop used to build the graphs in my previous post. The 97 is proudly displaying 165,000 miles on the OD and still look'n sexy.
Thanks a lot, I tried a trip today from springfield to worcester and set cruise at 65....however there wasa traffic jam which I avoided and took the back road (half 35mph half 45-50mph) and I got around 20mpg, no scan gauge but before I left I got gas when the tank says "7/8 full" and brought it to a little over full for under 3 gallons, 50 miles later its sitting at 15/16 so im assuming ~2.5 gallons used making it 20mpg, a bit better than the 16-17mpg i usually get. I know its not linear, but starting at 55mph you seem to go down around 1mpg for every 5mph in road speed, and me travelling at 75-80mph which I used to do would give me that range. Thanks for the data and I'll have to invest in one of those when money starts flowing in.
ScottB, any numbers from that road trip you took? In any case, 5-90, do you think you'd get better gas mileage from 225/75R15 or 235/75R15, or even 30x9.50R15? Right now I'm using 235's, but I have a set of 225's at home, but am looking into 30"? With the 30" tire Id have more miles/rpm but im not sure if the load would increase too much vs. having skinnier, lighter (just a guess) 225's?
5-90
NAXJA Forum User
- Location
- Hammerspace
BBeach said:
I've been reasonably happy using 30's on my stocker 88 - but I've got my own work to do on it (I'd like to pick it up 4-5", then go with either 4.10 or 4.56 when I build the two D44's I've got - I haven't decided yet.)
It's not like using a pizza cutter would be any help on an XJ - maybe if the vehicle were slighly more aerodynamic than a brick. However, I honestly think you're better off with a larger contact patch. The savings in aero profile you'd get with narrower tyres is minimal (at best...) considering the basic platform.
225/75R-15 ~28-1/4" tall, ~8-5/8" wide
235/75R-15 ~28-5/8" tall, ~9-1/4" wide
Not enough of a difference to worry about - so I'd just mount the wider tyre for a bigger contact patch and call it done.
streetpirate
NAXJA Forum User
- Location
- Oregon City, OR
with the aw4, i get a little worse mileage with 30x9.5s than with my 26.5x11.5 summer tires, with 3.55 out back. that or my odometer is off that much because of the tire height. thats 80% freeway.
Got crazy for me this week and just got to this. Don't know how to post an excel graph visually. Anyway, here's a description. Looks like a lot of factors in fuel mileage. I took my data in 10-mile segments on cruise (2Hi) to average minor variations. I was on I-71 between Cinci and Columbus, so I thought it was pretty level. Wind resistance has a LOT of effect. Had 3-4 mpg fluctuation at 65 mph 20.8 - 24.2. Granted, it was snowing and blowing like all getout. Plotted on a scatter graph and used excel 2nd order polynomial regression. Mileage peaks at 22.3 mpg at 66.6 (evil!) mph from the regression. 13 data points between 60 and 75, some repeated. I'll keep adding data to the graph as I go to and from work.
For reference: '01 XJ Limited 4dr 4wd Selec-Trac, 3.07 rear?, auto, stock engine, 17 inch wheels, crappy tires, tow hitch
Didn't track this, but ignition timing was 39-40 while cruising, as high as 42 on acceleration (medium). RPM's were in the 2300 range cruising at 65.
I expect the mileage value to change as I add data, but not the peak speed really.
For reference: '01 XJ Limited 4dr 4wd Selec-Trac, 3.07 rear?, auto, stock engine, 17 inch wheels, crappy tires, tow hitch
Didn't track this, but ignition timing was 39-40 while cruising, as high as 42 on acceleration (medium). RPM's were in the 2300 range cruising at 65.
I expect the mileage value to change as I add data, but not the peak speed really.
So you're saying that the mpg went from 21 to 24mpg at any given moment in time due to a gust of wind? Good data too, I think im going to spend more time around 2000-2250rpm, maybe 65-70mph or so. I took the backroads home last weekend and got 18-19mpg, half the trip at 50mph and the other half was city driving 35mph + stop and go. I filled up when I got home and again before I left to see my city mileage with somewhat aggressive driving and got 15mpg exactly.
Not exactly. First 10 mile stretch at 65 averaged 22.3 mpg, second stretch averaged 24.2, third stretch averaged 20.8. Samples weren't consecutive. and some higher and lower speeds in between. Close enough to random for me.
I can post data table if wanted.
Today my ignition was 36-37 and rpm about 2200 cruising at 65, so it looks like I had a reasonably strong headwind for my data. More passengers/cargo, too.
I can post data table if wanted.
Today my ignition was 36-37 and rpm about 2200 cruising at 65, so it looks like I had a reasonably strong headwind for my data. More passengers/cargo, too.
Thats interesting about the MPG, having the conflicting results of MPG dropping after 55 or 65:
The ignition timing was also interesting, thanks for collecting that data. I had just assumed that max advance was 36, but it appears its as high as 42 under lean cruise as you stated. Two areas at important, the lean advance for maximum MPG under cruise, and a under full load(low vacuum , high RPM). Can you log advance, at some reasonable refresh rate? It would be interesting to see a WOT run, what advance it maxes out at, and how soon it reaches that max. I'm guessing 32 degrees at maybe 3000 RPM, mind if you get a change, checking that out?
I made lots of progress on my computer, but it will have to wait until this semester is over until I can do more work on it. I going to made a circuit to input the VSS(vehicle speed sensor) to my computer(MegaSquirt) so I can figure out gas mileage. I need a frequency to voltage converter IC, which I will have to order. Then I can start posting finds of my own.
This is really interesting stuff
The ignition timing was also interesting, thanks for collecting that data. I had just assumed that max advance was 36, but it appears its as high as 42 under lean cruise as you stated. Two areas at important, the lean advance for maximum MPG under cruise, and a under full load(low vacuum , high RPM). Can you log advance, at some reasonable refresh rate? It would be interesting to see a WOT run, what advance it maxes out at, and how soon it reaches that max. I'm guessing 32 degrees at maybe 3000 RPM, mind if you get a change, checking that out?
I made lots of progress on my computer, but it will have to wait until this semester is over until I can do more work on it. I going to made a circuit to input the VSS(vehicle speed sensor) to my computer(MegaSquirt) so I can figure out gas mileage. I need a frequency to voltage converter IC, which I will have to order. Then I can start posting finds of my own.
This is really interesting stuff
scottbky said:
I assuming you mean idle in D ign = 14?
Im wondering why there would be difference between neutral and drive. I'm assuming neutral is same as park. I wonder if less advance at idle saves gas or something, or maybe its a emissions thing.
I would have though total advance at WOT would have been higher than 22, so thats pretty interesting. Thanks for the results.
