Steps We Took to Reduce our Electrical Energy Bills

In 1999-2000, the ranch was using 16350 kw-hours/year. By 2002, a serious effort at energy conservation reduced this to 8055 kw-hours/year. Our winter heating is by firewood, and our consumption of firewood decreased to about 70% of what it had been. This was achieved by simply doing standard things recommended by many organizations concerned with conserving energy. Specifically, we did the following:

There is still more we can do. In the winter, our main electrical energy consumption is the water heater. Solar water heating assistance should reduce that. We are still wondering about the advantage vs. expense of replacing our single-pane windows. Since our walls are a kind of adobe brick, the walls are a considerable heat leak that makes replacing the windows less effective than in a house with well-insulated walls.

Eventually, we would like to have large array of solar panels that put power back into the electrical grid. Since we have a grid connection, storing energy in batteries is not as practical as putting it back into the power grid. Unfortunately, the cost of solar panels has stopped decreasing and a completely honest calculation of the savings didn't justify panels even with the recent state rebates.

Reducing Our Gasoline Consumption.

2003 Prius - VIN JT2BK18U330073621 Engine 1NZ-FXE

The big step to reducing our gasoline consumption was to buy a 2003 Toyota Prius hybrid and to drive it gently. We usually get over 50 miles/gallon in the mountains, highway, and city. (The 2004 Prius gets about 10% better mileage!) This allows us to only use our 1991 Previa Van, that only gets 26 mpg, for hauling things that only it can carry.

We are 25 miles from the nearest sizable towns so our driving is usually 50 or more miles round-trip. If instead, we lived in town and most of our trips were only 5 miles round-trip, then our gas mileage would be much less. In order to produce "Super Ultra Low Emissions", the Prius heats up its catalytic converter at the beginning of a trip. This uses quite a bit of energy and makes the first 5 minutes of driving much less efficient. Also, the heater and air conditioner are necessarily electric since the gasoline engine is not always running. That makes for lower mpg when those features are used. These factors, along with aggressive driving habits might explain why many folks get much less than 50 mpg with their Prius hybrids.

Each year, I make several 535-mile round-trips to Los Angeles and have attained 57 mpg average for the trip several times. The key is to drive between 55 and 60 mph staying 200 feet behind one of the few trucks traveling near the California truck speed limit of 55 mph. At 200 feet back, there is no safety problem, one gets 1 or 2 mpg benefit from the truck's wind blocking, and other cars blame the truck, not me, for slowing down the right lane.

The Prius has all the power I ever need. There is no problem going up the "grapevine" grade on I-5 or accelerating when merging or passing. On only two occasions have I noticed the electric power assist being cut off. One was in going 55 mph while rising 4000 feet at a 5% grade (the "Shaver lake 4-lane") while carrying 650 pounds of humans and 120 pounds of camping gear. The other was going over a steep 9,624-foot mountain pass (Sonora Pass). I have never had any power reduction going over 9941-foot Tioga Pass or going over the Colorado Rockies through 11013-foot Loveland on I-70. Those passes have grades that are not as steep as Sonora Pass.

I have no idea when or how expensive replacing the big battery will be, but certain other aspects of hybrids should lead to lower maintenance costs. For example with gentle driving, the brake pads get very little use. Our Prius now has 128,000 miles on it and has needed no non-warranty repairs, shows no sign of deterioration in mpg, and the brake pads have not yet needed replacement. Of course, we change the oil and oil filter every 7500 miles. The engine is less stressed and runs less often so its bearings, etc., should last perhaps 40% longer. (I believe its oil pump is electric so that the engine can be certain to be fully lubricated before being started.) Also, the Prius' transmission is actually a fixed planetary gear system with no clutch and far fewer parts than normal stick or automatic transmissions. I expect no "transmission" problems for the life of the car. The brushless electric motors will have bearings that eventually wear out, but so far no hint of trouble.

My first serious Prius repair experience

Finally, at 128500 miles, I have had a significant problem with the Prius. Its warning light suddenly came on without any noticeable change in performance or mileage and I drove it 10 more miles to the Merced Toyota dealer. They read out the code, told me that cylinder 3 was misfiring and that I had a bad ignition coil on that cylinder requiring $270 to repair. I reluctantly paid their $110 charge to read out the code, told them to reset the warning light, and drove 46 miles home without any further difficulty. They claimed that my failure to change the spark plugs at 100,000 miles was the cause of the problem. I bought new iridium-tipped plugs and ordered an OBDII readout device (Cen-Tech Item 99722) from Harbor Freight for $115 (including tax and shipping), and read up on misfiring Prius reports on the Internet. In the process, I noticed that I could check the voltage of the 12V auxiliary battery by doing some finger magic on the Multi-purpose Display. Without any extra load, it was low at 11.3 V and I did not seem willing to charge up to above 12 V so I bought a replacement on from That battery had not been replaced since the car was bought in 2003, so I didn't feel bad about replacing it before I was sure it was the cause of my misfiring problem. It turned out to not help that problem, but at least now I can be confident that the auxilary battery voltage will stay above 12 V for another 5-7 years.

At about 153,000 miles, I accidentally left a rear door cracked and somehow that drained the auxilary battery so far that absolutely nothing happened when I turned the key 5 days later. The service manual warned not to use a "Fast Boost Charger" but rather to jumper it to a running car. It was ready to go in about 1/2 hour. I think there may be a place to jumper to under the hood of newer Prius models, but our 2003 model requires exposing the auxilary battery at the left of the trunk to do the jumper operation.

Then I switched the coils on the #2 and #3 cylinders to see if the cylinder that was misfiring would change to cylinder #2. It did not, so I concluded (incorrectly) that the coil was not bad.

Next, I suspected the fuel injectors and chose to try a gasoline additive, Techron from Standard Oil, that some folks have spoken highly about. That seemed to help a bit, but after a couple of months, the problem came back as before and getting worse.

I finally bought a set of Toyota service manuals (total cost $200 from Toyota). When I bought the car, the 3 manuals were $200 each and I decided to not purchase them until I needed to. The time has now arrived. The manuals are extremely useful and should be purchased by anyone planning to do their own repair after the warranty expires.

After performing resistance tests on the fuel injectors and finding no anomaly, I noticed that the manual hinted that the P0303 readout may not really be caused by cylinder 3. The cylinder firing before cylinder 3 might be the cause. I then swapped the coils between 3 (which by then had the coil originally in cylinder 2) and 1 and the misfire code switched from cylinder 3 to cylinder 1!! That proved that the problem was indeed the coil and I bought a replacement which finally fixed the problem.

As I wrapped up my fix, I got an error message telling me that reminded me that I had disconnected the fuel pump. Then another message after my test drive told me that I had not closed the gas cap again. Being able to readout the error codes is extremely helpful.

A few thousand miles later, I needed to replace another coil. Shortly thereafter, I replaced the remaining two coils without waiting for them to fail.

Checked Brakes at 139,000 miles

The brake light occasionally comes on for a short time without any accompanying sounds so I checked the brake fluid and pads. The brake fluid was near the max line and has yet to need topping off. Also, none of the brake cylinders showed any signs of leaking brake fluid. The front brake pads were 5.5 mm thick with 11 mm being the "STD" value given in the Prius service book. The rear brake shoe lining thickness was 3.5 mm with a "STD" value of 4.0 mm. In both cases, the specified minimum value was 1.0 mm so I guess my first replacement of the front brake pads will be at about 200,000 miles. I still need to figure out why the brake light is coming on. The book suggests low booster pump pressure.

At about 141,000 miles, I needed to replace a front tire lug stud (as a result of my own mistake). The replacement stud was cheap and easy to obtain at a parts store, and its replacement was easy once I noticed that it is necessary to rotate the wheel so that a dimple in the metal behind the brake disk was lined up with the stud to allow the stud to be knocked out.

By 141,595 miles, the brake light had become more insistent, and it was clearly activited more by going around turns than by applying the brake. I added brake fluid (DOT 3) to bring the level from min to max and the occasional brake light indication ceased.

More Misfiring at 142,000 miles

At around 142,000 miles, I began having error codes indicating a misfire problem. The plugs looked good with the proper gap, so I expected the misfiring was caused by something else like the coils or injectors. As it turned out after much incorrect deduction, the plugs were actually the problem. The Autolite iridium-tip plugs I had used to replace the original plugs at 128500 miles did not last well. I was told that "Of course, you should have used NGK or Nippon Denso plugs. They are the only good ones." That advice was correct; the Autolite plugs started giving trouble after only about 15,000 miles. Once I put NGK plugs, in the misfire problems vanished. I was also advised to stay with genuine Toyota coils, but at the moment my replacement coils consist of 3 after-market coils and one Toyota coil.

The bottom line on maintenance is that at 154,000 miles, it appears other than regular changing of the oil filter and oil, I have only needed to replace the plugs, coils and auxilary battery. Maybe I really didn't need to replace the coils or the auxilary battery, but I am not sure. I am determined to self-maintain as much as I can on the Prius and that means sometimes I will replace something that didn't need replacement.

At 154,000 miles, I still average over 50 mpg which means I have needed 3080 gallons of regular gas at a cost of perhaps $10,000. I have saved $5000 in gas over a car with 25 mpg and this 2003 Prius is continuing to run run well while gas prices are rising.

Very Serious Misfiring at 160,400 miles

The car had been running smoothly for the past 6,000 miles when one morning it abruptly gave a check engine light and indicated misfiring. A little while later, the misfiring became very severe and we returned home. The problem turned out to be a dead coil in cylinder 3 even though the car claimed that the misfiring was in cylinder 1. As a result of my playing musical coils, I also found that when the bad coil was in cylinder 2, the car claimed that the misfiring was in cylinder 4. The firing order in the prius is 1-3-4-2, so the problem was actually in the cylinder that fires after the one blamed. (Note: This contradicts what I said earlier. In any case, don't trust the car's identification of the problem cylinder.)

As a precaution, I also replaced all plugs with new iridium NGK plugs.

During my testing, I found evidence that rainwater had seeped under the hood onto the coil area and leaked past the coil gasket into cylinder 1. It had dried out, and that turned out to not be the cause of my immediate problem.

The Toyota service book says that one can check the coils by looking for a spark when the coils with a spark plug are all removed and checked outside of the cylinder. The frame of the plug must, of course, be grounded for that test. Toyota says to disconnect the injectors to avoid gas being sent into the cylinders. I adopted a much easier approach of using an extra plug for the test and leaving all cylinders with their plugs intact. That way no gas mixture could escape during the test. The bad coil simply had no spark at all. In some cases, I suppose a coil could be bad and simply produce a weak spark.

Traction Battery Replacement at 166,430 miles

June 8, 2013: At 166,430 miles, it was necessary to replace the traction battery for $3022. Check engine light and readout codes showed some cells recharging time was out of specs. It seemed best to not mess with individual cell replacement. The new battery is alleged to be of improved design. Toyota claimed that replacement at 166,430 miles is one of the earliest they knew of. They thought the new one should last well over 200,000 miles. Perhaps my gentle, high mpg driving led to more rapid battery wear.

Again Serious Misfiring at 186,424 miles

Bought a new coil ($104.58) and set of plugs (4x$10.37) from Toyota. Using the testing method described above, I found that the coil on the #3 cylinder was bad and replaced it. The repair was successful and I did not put the new plugs in yet. I plan to do that at about 200,000 miles. I think I now have genuine Toyota coils (just checked by feel for logo) in cylinders 1,2, and 3, but #4 is still an after-market coil so the next one to go is likely to be on the #4 cylinder.

Once again Serious Misfiring at 214,802 miles

It suddenly started to misfire badly as I left for school. I was able to limp the 90 miles to my teaching and back, but it was not at all clear that I would make it. Without opening the hood, I concluded that the problem was the same as 28,000 miles earlier and bought 4 new NGK iridium-tipped plugs and spark coil. I wanted to get a genuine Toyota spark coil, the the dealers were too far away and the one I checked in Fresno wanted me to make two trips - one to pay for it and a second to pick it up after they got one from a warehouse. I ended up buying an after-market one (box says "ImportDirect, 23-0203, 90919-02240 Coil, Made in Japan) from O'Reilly. My engine computer readout said "multiple cylinder misfireing and also specified cylinders 1, 3, and 4. When I took it apart and examined the plugs, the #4 plug looked like it had not seen explosions lately, but the others might be Ok. I also measured resistances of the coils in all combinations of its 4 pins and both polarities, but could not come to any conclusion. They appear to have diodes and some smarts that prevented my analysis - not all gave the same readings, but the #4 coil looked particularly suspicious. That #4 coil was not a Toyota coil although the other 3 were. When I replaced it and all plugs, the misfiring was cured. A drive to school the next day produced 50 mpg and no misfiring.

More trouble about 200 miles later with code 3191

I cleared it, but it may return because there was some hint of misfiring.

Engine Air Filter Mice Intrusion

At 239000 miles, I belatedly got around to checking my engine air filter again and found that mice had been there leaving poop and olive seeds. It was quite a mess, but they did not penetrate below the upper part of the filter. That a mouse could climb up the air intake strikes me as a Toyota design error!

More about the Prius technology

See Graham Davies' excellent, detailed discussion of Prius technology.

Also, see an excellent discussion of Prius fuel efficiency at the web site of the Chicago Prius Group. I do however, quibble with his claim that mountain driving is not as efficient. I do almost only mountain driving and find that the ups and downs tend to help unless a single uphill or downhill stretch spans more than 3000 feet of elevation change.

Even our 1990 Honda Civic Wagon gets 43 miles per gallon when driven 55-60 mph with gentle acceleration. It now has 300,000 miles and is still used occasionally.

A more efficient weed-eater

We also bought a new Honda 4-stroke weed wacker which uses far less gas than its predecessor.

Last updated: April 29, 2018

Valid CSS!Valid XHTML 1.0 Strict

Contact Craig Van Degrift if you have problems or questions with this web site.