Really Bad Gas Mileage
- Thread starter RCC
- Start date
not to say that you're bad at math or anything, but just make sure you double check your math and conversions... i just don't want you to be tearing your engine apart for no reason or wasting money on unnecessary parts is all 
and getting 15 mpg during the winter once or twice isn't bad, i've had it happen, where i let it warm up or drive it hard, or drive short distances...but if it's for more than a couple of fill ups and during warm weather normal driving, thaaaat's when you need to start looking at some things.
and getting 15 mpg during the winter once or twice isn't bad, i've had it happen, where i let it warm up or drive it hard, or drive short distances...but if it's for more than a couple of fill ups and during warm weather normal driving, thaaaat's when you need to start looking at some things.
The new O2 sensor has been installed. This is a Bosch aftermarket unit. I did not use the splice kit that came with the sensor. The instructions left me a bit cold regarding obtaining a positive connection with the wires. Instead, the wires were spliced with crimped butt connectors and shrink-tubed. I used the red connectors (18g?) and removed the plastic insulation. There were no CELs on starting the engine.
Once up to temperature, the scanner was attached to determine if any changes were noticeable compared to the original Denso sensor. The crossing time (period) was essentially unchanged, about a second. Perhaps the crossing time is determined by the ECU as much as by the condition of the sensor. The engine does appear to run a bit smoother at idle.
The effects on fuel economy remain to be seen. I leave tomorrow morning and the forecast tonight includes snow. Total driving time this weekend will be over 14 hours, all on interstate.
Once up to temperature, the scanner was attached to determine if any changes were noticeable compared to the original Denso sensor. The crossing time (period) was essentially unchanged, about a second. Perhaps the crossing time is determined by the ECU as much as by the condition of the sensor. The engine does appear to run a bit smoother at idle.
The effects on fuel economy remain to be seen. I leave tomorrow morning and the forecast tonight includes snow. Total driving time this weekend will be over 14 hours, all on interstate.
wow you are getting really bad mpg.. so what was your constant speed during the trip? because that also plays a factor too. my 01 protege-auto is getting ~30mpg, the other day I got 30mpg during a 600+ mile trip with an avg of ~65mph and I also have a CEL.
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This was a pure interstate trip, approx 70 mph. The only time not at 70 mph was getting on and off the road for gas. At 65 mph, I may approach 30 mpg. I still compare this to the 2007 Mazda3 that we just got rid of. At 70 mph, that car would get 33 mpg.
The only obvious difference between the 2.0 L engine the Protege5 and 3 share is the timing. Unless someone disputes my observation, I remember seeing timing advance of 40-50 degrees on the 3, and am seeing about 30 degrees max on the P5. The timing advance is very sensitive to load tho. High advance at light cruise, retarding as the cruise picks up load on a hill. Just for note, this is a 2002 P5 with auto.
The only obvious difference between the 2.0 L engine the Protege5 and 3 share is the timing. Unless someone disputes my observation, I remember seeing timing advance of 40-50 degrees on the 3, and am seeing about 30 degrees max on the P5. The timing advance is very sensitive to load tho. High advance at light cruise, retarding as the cruise picks up load on a hill. Just for note, this is a 2002 P5 with auto.
I did a little research for the sake of comparison. The 2002 Protege5 has a weight of 2716 lbs and a drag coefficient of 0.32. The 2007 Mazda3 has a weight of 2780 lbs and a drag coefficient of 0.29. The values are from the Cars Direct site.
The air pressure in my tires is 32 psig.
The air pressure in my tires is 32 psig.
