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Ceyarrecks 12-23-2008 07:44 AM

Scion xA woes
I recently found this forum while searching for information on the xA I have.

the woes detail how I have been struggling to get this xA to perform. And the multiple problems being dealt with through the dealership in Lancaster.

My daily commute is 55.5 miles one way, and 95% of this is highway/highway speeds (55mph on 997)

my standard I choose to hold all cars is the 55mpg I had while using a 2007 Prius, and the sad point is that I drove without any extra technique, no slip streaming, no neutral coasts, etc.

the ONLY way I can get the 450mile per 12 gallon full tank (37.5mpg) is by slip streaming all highway travel. the higher RPM while the engine decides to warm up is frustrating me to no end.

the tires are oem and filled to 50psi (i had to refill them after the dealership called themselves doing the econo-maintenance and dropping psi to 35!?!?)

I make it a point to keep RPM at or below 2k during accelerations, and neutral coast when ever i can.

sadly, all this still only nets me 37mpg on a good week. less most times.

my questions are:

is it possible to adjust the car's computer to NOT prevent the trans from shifting to high gear with "x" temp? I angered that I am going >3k at 40MPH!!!!!!:eek::eek::eek::eek::eek:

can one just disconnect the thermostat to effect the same change?

as far as covering the grill, given all else being equal, how much does that help?

also, has anyone had any experience with using water electrolysis (electrically breaking down water to O2 and H)?

I have read a few articles that suggest a massive amount of fuel economy increase. (considering the volatile nature of straight O2 and H, i can kinda see that point)

it seems there are kits available that only require tank installed somewhere in engine compartment, hose to air intake, done.

also, the xA stands exceptionally high. 6 inches at least compared to a Nissan Sentra, what would be the benefit to lowering the suspension of this car?

Thank you for the response, I hope to get this disappointment of a car set to better perform through the help and expertise here-in.


almightybmw 12-23-2008 08:37 AM

Not knowing the xA very well, there's lots of things you can do that'll help, and some that'll make things worse. Warm air intakes (piping to the exhaust manifold to bring in hot air instead of cold air) are not universally good. Some engines just don't like them. My GP doesn't, but my truck does.

Disconnecting the thermostat isn't a good idea, as many things rely upon it. Forcing your transmission (assuming auto?) to stay low while cold is hard on the fluids and could lead to premature failure. Not sure how to fix this, other than make a tranny block heater to warm it up faster. I have this issue, and at -20 it shifts kinda hard for my liking, even when mostly warm.

grill block good. do a nice one and it'll increase the aero of your xA as well as warm up the engine. There is no universal % gain, it varies vehicle to vehicle.

Ignore the electrolysis. Some say it works, some say it doesn't. Still waiting on empirical evidence (ie a closed loop track test) showing the differences. Mixed highway/traffic light driving is too varied for real testing.

Lowering the car decreases your frontal area. Less air to push, less HP required to move it. It's a good idea IF you think you can save in fuel costs from the lowering springs. $150 in gas get's me a pretty long distance.

There's a start to answering your questions. Others will have opinions and facts to help as well.

Welcome to the forum, hope the knowledge gained here helps you push the xA to above 45mpg. That car has potential.

Ptero 12-23-2008 01:09 PM

The drag coefficient on the Scion sucks eggs. I've seen it rated as high as .37 while the Prius is rated at .26. That is an astounding difference!

At speeds above 60 mph, more than half an average vehicle's horsepower is used simply to push air out of the way. If you are so inclined, you could find out how fast your Scion would go to create the same amount of drag that the Prius encountered at 65 mph. The disappointing result will likely be in the mid to high 40s.

Use this formula.

The force of drag equals half of 1.3 kilograms per cubic meter times the speed times the frontal area of the car times the coefficient of friction.

Sad to say, you can try all the aero mods on Ecomodder but you will find the single most effective thing you can do to try to close in on the mpg of the Prius is, by far, to slow down to that 40 mph range in top gear and keep your speed constant on level terrain.

As to the onboard electrolysis unit, I have yet to see one single study that indicates there is any measurable gain. Fundamentally, pulling energy from a closed system (your car) to manufacture a secondary form of energy (hydrogen) that is returned to the closed system (your car) can result only in losses associated with the unnecessary conversion of one form of energy (electricity) to another (hydrogen) which is simply returned to the system.

In fact, if you have a vehicle with an onboard electrolysis unit installed, you should be able to achieve a slight performance gain by removing it.

Now, if you were to take hydrogen from outside the system and add it to the system, that would certainly be beneficial. But that's not what we're talking about with onboard electrolysis units.

NeilBlanchard 12-23-2008 01:32 PM

Hi & welcome to the forum,

Good highway economy = good aerodynamics. You need to do an upper grill block, to start with, and smooth wheel covers will help a lot, as well. Here's the thread I started on my xA:

Those are the two biggest improvements for me. A couple of the other helpful mods were the fog light covers, and the zigzag tape at the top of the windshield. My high is 47.5mpg and during the summer I averaged 45.5mpg. My smooth wheel covers have a good chance of getting me above 50mpg (I just added them when I switched over to my snow tires). My goal is to stay above 40mpg this winter -- and so far, so good!

The only Cd that I've seen for the xA is 0.31, btw. Yes, the Prius does well with a lot less effort -- I drove one for two tankfuls, and got ~52.5 and ~53.5.

Oh, and you probably should get a ScanGauge II -- that has really helped me a lot! And having a coolant temperature gauge also helps a lot; my grill blocks (~3/4 of the entire grill is covered) makes virtually no difference in the engine temp, at maximum, though it helps shorten the warm up time.

Ceyarrecks 12-24-2008 03:26 PM

thank you kindly for the responses.

I actually do own a SGII, though I doubt I am using it to its fullest potential.
(I find it amusing that my MPG = 9999 while the engine is reving to slow the car down :lol: I try to avoid this, and neutral coast when able)

I have begun to price lexan and secure this to the grill itself to be flush with the body.

I was also thinking about the eye-sore wiper arms and how I could include them in an improvement scheme.

any material can be basically be used to make more smooth the hubcaps, eh? something shrinkable i would expect.

my best at 12 gallon/tank full is 460 miles, which roughly equates to 38MPG.

and that is mostly by slip streaming trucks.

when i first got the car, I did all driving regularly, no trucks, nothing extra, this car gets mid 20s MPG :mad::mad::mad::mad:

yet when I had a prius for 3 days straight, same drive to work as usual, it registered 51 and 58 MPG receptively (to/from work) on each of the three days. I hold all cars to that standard.

NeilBlanchard 12-24-2008 03:57 PM


Actually, the 9,999mpg is real! When the engine is being pushed by the wheels, the ignition computer shuts off the fuel completely -- and so if you need to slow down, using the engine for this will help your mileage.

If you need to carry speed, then coasting in neutral is the way to go.

I think a grill cover made out of a vinyl fabric (like those "bras") would be a better way to go on the grill block. As I mentioned, acrylic is great for covering the fog lights; if you have them. If you don't have them, then covering the "dents" will help you get more mileage.

Have you actually pumped 12 gallons into the tank? The most I ever have pumped is ~11.4; and typically, I put between 9.5 and 10.5 gallons. The most distance I ever got on one tank was 509.3 miles, and it took 10.71 gallons to fill it = 47.55mpg. I think if you log the actual gas you pumped, you'll find that you are getting better mileage than you think! I'll bet you got well over 40mpg on that tank.

And you really have to calibrate the SGII, so it will be more accurate! The gauge in my Mom's Prius was way too optimistic -- it said 59mpg, but in reality, I got 52.5 and 53.5; calculating with the amount of gas I actually pumped into the tank.

To calibrate the SGII, each time you fill up, hit the Home button, then More, then Fillup, and adjust the amount displayed to be what you actually pump; after you do this 4 or 5 times, you will start getting much more accurate MPG readings.

The wipers do not hardly get hit by much air, in my experience -- the front fascia (bumper, grill, and chin spoiler) deflects the air up to about 1/2 way up the windshield.

You can use pizza pans as wheel covers and figure a way to fasten them on, or you can purchase 15" snap on covers from Hubcap Mike's for ~$100 shipped.

Ceyarrecks 12-27-2008 12:47 PM

might as well be total of 12 gallons, the car is listed as having 11.9 gallon tank, and I fill it to the cap.

most refills are at E, and the gas pump icon was flashing for last 20 some-odd miles. amount I put in are usually about 11.5(ish) gallons.

I have yet to run the car dry, but I would be interested in exactly how much the car can hold.

On my next fill up, I will note how much I put in and adjust the SGII accordingly. '

One thing I must say about the Prius, is that I appreciate the MPG efficiency over time graph it provides. the SGII seems to just tell you "at_the_moment" readings, which is difficult to monitor while driving,...

Is there any way to hook up the SGII via its RJ45 connections to a PC for downloading information out of it? the instructions ever made mention of this.'

Thanks again for the input.

MetroMPG 12-27-2008 05:27 PM

Sounds like you are only using the ScanGauge's "instant" MPG reading on the GAUGE screen. While useful in certain situations, you also have access to resettable TRIP, TODAY and TANK mpg.

I highly recommend (a) the grille block; and (b) an electric block/coolant heater.

It's worth noting as well that you will get your lowest fuel economy in winter months for a variety of reasons.

NeilBlanchard 12-27-2008 05:34 PM


You have to calculate the mileage by dividing the total mile by the amount of gas you actually pump; because the gas gauge is not accurate enough -- and unless you run it dry, you will never use all 11.9 gallons. And even then, it is unlikely that you could get precisely all of the gas out of the tank.

As I said before -- I'll bet you are getting much better mileage than you think you are. Keep a log and do the math -- you will be happier with the results.

And please do calibrate the SGII using the Fillup screen to adjust the amount that it "thinks" you have used to be what you actually pump in. If you use the same pump each time, and try to fill it to the same point, you will get it to be much more accurate after 4 or 5 fillups.

deizel295 01-08-2009 10:41 PM

that Xa has a toyota yaris/fitz/echo drivetrain, look stuff for that car. DO NOT disconnect the t-stat, that will kill your mileage. further; OBD2 vehicles will instantly see the problem, set a code, turn on the MIL and revert to standard fuel maps that are MUCH LESS effiecent that when the vehicle is in closed loop (full operating temp in a certain period of time, very sensitive on the 1.5 next gen controller, read pcm) and is actually using the HO2S (heated oxygen sensor) modern oxygen sensors have to be at 900 degrees or better to be accurate so PCM's are programmed to ignore them until the temp is reached, hense the heated sensor; to get them there quicker. this is also why honda's have thier HO2S right in the manifold within 2 inches of the exhaust valve, to get hot FAST. the 2007 PZEV civic goes into closed loop from cold start in 22 seconds !!! now thats a nicely built car.

a side note on the Xa, while yes it has slightly poor aero features you CAN change some things to help yourself out.

1. make sure you have iridium plugs in the engine; the echo's will set misfire codes even if thier not missing without iridiums, same engine.

2. THINNNNN oil.

3. follow other advice from others here on the forum, but be cautious, if it trigger's a CEL (check engine lite) then it's not doing good things. a CEL ONLY comes on if the federal test protocol emissions CAN (not are; CAN) go above 1.5 times the manufacturers test results.

any questions let me know. we work on six of these cars and they have some interesting changes from year to year and trim levels.

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