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Discussion Starter #1
At 76816 miles, my MPG was 68.6 on October 3, 2002. At the next tankfill, I noticed that my MPG drastically reduced. By early December, my MPG was down to the upper 30's. Constant complaints to the dealer resulted in the battery and O2 sensor replacement, with resultant MPG in the low 40's. At 97440 miles, the valves were adjusted, sparkplugs replaced, my total MPG reads 60.8 and my average is 53-54 MPG at each tankfill. Honda Tech Support claimes that the high 40's to low 50's is "normal" for Insights in my area. Consequently, my Insight is parked at the dealer's until they find the problem.

One note: At 93764 miles, while on a level freeway, I heard what sounded like a backfire (with meallic overtones) and my indicator jumped from 40 MPG to 78 MPG and experienced a burst in engine power. This lased for 42 miles, then dropped back to 37 MPG. This has happened periodically, lasting from 1000 yards to 40 miles(very rare).
 

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Both my Chevy Sprint and Geo Metro have done that. Both times it was the catalytic converter.
Good luck Louis
 

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You didn't mention where you are. December is the coldest month. The Insight gets much worse gas mileage in cold weather. Likely, it is because the battery chemestry slows down in the cold, so you waste watts while shoving a charge into the cold batteries and waste watts trying to drag a boost out of them. The gas engine is less happy in the cold, too. High 30s is not uncommon when the outside temp is below freezing, unless you drive far enough to warm everything up (but the cold beginning of the trip still features bad mpg).

I wouldn't expect catalytic converters to be a problem until the car is old. Sometimes old converters burn out and what starts as a honecomb through which exhaust flows turns into a solid wall when part of the honeycomb breaks loose, rotates and clogs the exhaust so the engine can't breathe well. You then get bad performance AND bad mpg.
 

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Battery replacement

Iodiee,
When you had your battery replaced did Honda pay completely for the labor and battery under their 8yr/80,000 mile warranty? Or did they prorate battery usage and charge you for the unused portion of the battery? :roll:
 

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Discussion Starter #5
I live in the Mojave Desert, driving 86 miles each way between the ranch and my office in Burbank. The Insight is used only to drive to work and jobsights. The tank is filled at only pump # 4 at one Shell station. I use odometer "A" for tank usage and "B" for daily readout. My drive includes 23.6 miles on paved country roads, 1.5 miles city streets (3 stop lights), and the balance on freeway that has hills. Ranch elevation is 2531 ft., the top of the pass 3428, and Burbank is 655 ft.

I received my driver's license in March, 1942, when gas rationing limited me to 3 gallons per week. I learned early to be lightfooted. I became a pilot in 1944, learning (in a P-51) to CONSTANTLY watch my instruments. In 1950, I got my PH.D. in Mechanical Engineering. That is why I keep a log book, and refuse to accept Honda Tech Support's assessment that I do NOT have a problem. My mileage does vary with the weather (which I keep track of, since I wrote the Weather Data Handbook for California, Arizona and Nevada). However, the variation is slight.

I have an appointment to fight with Hoda's "Chief Engineer" this Friday at 10:00. So any ideas would be welcomed.
 

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I would suggest printing out some data from the InsightCentral mileage database to show what kinds of mileage people get with comparable driving habits in the same model Insight (you haven't said whether you are driving a 5spd or CVT).

I don't think it is reasonable for Honda to tell you that 40-50 mpg is reasonable when you have gotten nearly 60+ mpg in the same car.

Good luck,
 

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2001 5S "Turbo"
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sudden drop in mileage

So what was the results of the session with the tec person? It is only courteous protocol to keep the group informed of the results because of the magnitude of the problem indicated by you at the start of this thread.
 

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Discussion Starter #9
The Honda District Service Manager refused to authorize any work or analysis of the problem, saying that I should not expect over 50 MPG. This, after I showed him the survey of the other Insight owners in the area that drive similar trips that I do. I then took the car to the most experienced dynomometer tester in the area. The results, corrected to sea level (we're at 2600') indicated 69% of rated horsepower at 5600 RPM and 71% of rated torque at 2500 RPM. To me, this indicates a false signal to the ECM/PCM or a defective ECM/PCM.

My theory is further reinforced by three incidents, the last one occuring this last Wednesday. I was driving home, when all of a sudden I felt a burst of power, the MPG gauge jumped from 40 to 75. I immediately punched my Trip "B" odometer to zero. When I reached the ranch (12.3 miles), the MPG was 78.3. Thursday morning I drove 34.5 miles, mostly a slight uphill grade and my MPG was 72.3at that point. A few hundred feet further the road started a slight DOWNHILL grade. The car acted as though it suddenly hit a mud filled dirt road - the downshift light came on, and the MPG dropped to 35. So, I am back to my original problem, with only a few hundred miles left on my warranty.
 

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2001 5S "Turbo"
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Sudden drop in mpg

Have you tried resetting the ECM? I drive mainly in the 4500 foot elevation and have a lifetime mileage of 59.6 for 79,200 miles. Most modern vehicles are "programmed" for sea level specifications. Once a year I routinely reset the ECM.
 

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drop in mileage

Sorry about that I meant to say 2,500 ft. elevation. Still got "jet lag" from the trip to Fla.
 

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Here's some suggestions of things you should check out.

From your first post, I think you need to check for exhaust restrictions. One of you cats may have failed. (Yes, cats can fail and become clogged.) Unfortunately checking for this is not trival.

You should also check for something clogging the intake side. A clog here may cause your engine to run rich and backfire.

You also should check for drag in the drivetrain. Ecspecially for dragging brakes. Worn pads can become jammed. I've seen on drum brakes where a lining broke off a shoe and became wedged in the other shoe.

I take it the check engine light has not come on. You should check that the light still works.

I don't have any advice for getting honda to fix your car. I'm in the "If you want it fixed right, do it yourself." catagory. After all, if your car fails because of faulty maintenance, it's not your mechanic who is stranded.
 
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