I may do the same thing this
 

I may do the same thing this weekend if I have the time. If I only had cruise control.

just switch to EX harneses.
 

just switch to EX harneses. thats got MPFI and cruse allreadt in the harness.

re: cruise - i think i read
 

re: cruise - i think i read before that you've already got the parts from another vehicle, right matt?

otherwise... i got a used aftermarket unit off eBay for my car for $106 CDN - including shipping & currency exchange.

it wasn't difficult to install, but took an afternoon to do it (most of the time was spent planning where it would mount & how to connect to the throttle or throttle cam). i ended up setting it up to pull on the throttle pedal arm since the cam on the TB on this motor was too tiny.

i even moved it all over from firefly #1 to firefly #2 when i got the black car. the second installation didn't take much time at all!

yes, I already have the
 

yes, I already have the cruise control stuff out of another car. The 88-89 civics didn't have cruise control, but the 90-91 civics did. Aside from a few superficial changes the 88-89 and the 90-91 are the exact same cars. As a result I can retrofit the 90-91 cruise control to fit into my 89 civic.

This requires replacing the steering wheel, the pedal assembly, and adding a control box, a "on/off" button, as well as an actuator. It also requires splicing some wires into the dash wiring harness. Overall, however, it will look completely OEM.

I have a rather big car
 

I have a rather big car weighing 1360 kilograms with a 2.0 engine and automatic trasmission.
So far the best MPG in this car is 5.3 Liter/100 km which is approximately 44 MPG.

It was 1.5 years ago at a summer night a 570km (356 miles) trip.. There was only me in the car and according to trip computer my average speed was 78 km/h (48mph). There was no traffic at all and i was driving below 90km/h (56mph) in order not to get a speeding ticket. I drove from cities from Ankara to Afyon and returned back. This road is the few most even roads in Turkey as there is no steep uphills and downhills.

But that was before i was aware of the gas saving issue.. and at that time cruise control was not installed in my car... If i would do the same trip again i think my MPG would be 50 or more..
First of all i would inflate my tyres to minimum 40 psi and use cruise control at cruising speeds of between 60 - 70 km/h (37-43mph), and use the oxygen sensor circuit to decrease the consumption at level roads and downhills. Oxygen sensor circuit dramatically reduces the consumption at part loads. But i dont have an idea whether its related with the onboard hydrogen generator installed in my car.

I did it -- 40 mpg highway!
 

Well, the challenge commenced today.

I needed to drive 250 miles each way to a class (by the way, it's for the SCCA National Rally Championship Circuit, which is coming to Missouri for the first time -- I'll be working medical crew on each stage. The OLN channel carries the Rally, which I think is currently in Michigan "Sno-Drift") I'm excited -- the Rally is on Feb 24-25.

Anyways, getting there was rather inefficient -- it took 10.437 gallons to go 286 miles (27.40 mpg). Speeds were 60-70, heavy rain, and lots of pooling water on the roadway. But get this, on the way home, I decided to set the cruise for 57 mph.

Driving on a Midwestern Interstate at 57 mph when the limit is 70 is not for the faint of heart. I got honked at once, plenty of dirty looks and lots of cutting-off. The goal was to see what kind of true highway mileage this car was capable of. Much to my surprise, the gas guage slowly dropped as the miles went by. Half-way through the tank, according to the guage, I was at 227 miles. Filling up at my usual pump, 4.748 gallons = 47.81 mpg! BUT, there's one problem. The first click-off didn't completely fill the tank.

The gas station 250 miles away from home filled the tank to the F-Mark on the guage at the first click, but Pump #20 at my local QuikTrip leaves it slightly off of the F-Mark at the first click. So, since the tank holds 12 gallons, and the guage read exactly half, I estimate that 1-gallon should be added for a closer-to-true measurement. 227 miles per 5.748 gallons is 39.49 mpg, which is close enough to 40 for me.

Of course, it will have to be repeated for confirmation, but I've come to the following conclusions:

My max highway mileage is at least 40 mpg at 55-60 mph.
Wind resistance really has an effect on my mileage -- driving over 60 really takes more fuel -- I should focus on making the vehicle more aerodynamic.

RH77

I would of probably achieved
 

I would of probably achieved high 30's or low 40's if I drove during the day and not up the mountains.

I'll do the challange again but I'll change a couple of things. Most likely is pumping the tires up to 40 psi and driving 55-60. Plus I need to change the air filter.

xB odometer error
 

Ok here's a good reason that the ScanGauge is reading so high on my MPG and it doesn't come close to the odometer . . . the odometer is off and reads less that actually traveled. I just ran down the street 2 miles measured by my bike and scooters that have rotation calibrated digital odometers with 2 decimal places on the miles and the xB reads 2.0 miles on the ScanGauge at the 2 mile mark but the odometer reads 1.8 miles or about a 10% error. So the half tank mark on the gas gauge that I reached today on the odometer reads 247.1 miles figuring 6 gallons from a prior fillup when at half a tank indicating 41.18333333mpg but the ScanGauge is reading 253 miles 42.166mpg and the gas used at 5.6 gallons and 45.1mpg for the tank some of the error being the amount of gas used is more than the ScanGauge is measuring but not by much.

rh77 -
 

rh77 -

(and everyone else) - why not fill the tank more precisely than "first click"? i used to do first click, but (as you just confirmed), it's not consistent.

a far more consistent method is to actually fill the tank right up the filler neck until you actually see the fuel level at the little metal flap in the pump "hole".

the potential downsides to this are:

- in hot ambient temps you could theoretically have fuel spill out under pressure as it expanded (assuming you didn't drive the vehicle after filling up) - this hasn not happened to me.

- occasionally, you'll overfill, and a bit of gas will run down the paint & evaporate away.

- it takes longer - i'd say i go through 4 or 5 clicks before the level reaches the top of the filler neck to the little flap.

even this method is not 100% consistent (air pockets can be trapped in the tank depending on the angle of the vehicle when filling), BUT it's far more reliable than the "first click" method.

Re: xB odometer error
 

just fyi, JanGeo, my scangauge was 1% off on distance on my last fill-up (over 450 km). its mpg calcs are between 2-3% off (better than) my back-of-the-gas-receipt calculations. but this is within the margin of error since i buy volume-corrected fuel, and the volume on the receipt is not actually what i'm putting in the tank. (a whole other story).

i have yet to calibrate the car's odo, however. i have it on my list of things to do...