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96 Mazda 626 - very poor mileage


boxster's Avatar
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08-29-04, 11:23 PM   #1  
boxster
96 Mazda 626 - very poor mileage

My 96 Mazda 626 was getting very poor mileage (about 10 mpg hwy). I had a tune up done, and had the timing belt and EGR valve replaced about 2 months ago. The mileage returned to near normal. Then about a week ago the mileage dropped again to 10 mpg hwy. There seem to be no performance problems (good acceleration and smooth idle). The tune up was supposed to include new plugs, wires, fuel filter and air filter. I don't know of anything else that would affect mileage so much.

Any ideas on what could cause such poor mileage?

 
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08-30-04, 02:11 AM   #2  
there is alot of sensors that can affect fuel mileage but it is hard to believe the mileage is that bad and you are not having any drivability problems as it should quickly foul the spark plugs using that much fuel.
do you have a check engine light that ever comes on if so start by having the codes read.
do you ever smell gas while driving or when the car is parked?

 
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08-30-04, 02:01 PM   #3  
boxster
Yeah I agree, it is hard to believe that there are no performance problems. That's what's drivin' me nuts about this. There is no smell of gas in or outside the car. I think maybe the tuneup I had done wasn't done properly.

 
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08-30-04, 08:55 PM   #4  
I think your Mazda will stop running way before you get to 10 mpg. To have the mileage drop by 2/3 is very, very hard to imagine. You car should run like a it's only firing on one cylinder and the black smoke in the back would resemble a burning oil well.

 
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08-31-04, 02:54 PM   #5  
boxster
Again I agree. Think I better do some more careful checking. Maybe there's a leak that only occurs while driving. I appreciate the input.

 
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08-31-04, 03:01 PM   #6  
See if the fuel pressure regulator is leaking might not be the case but it's worth a shot.

 
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