2004 Honda Civic EX Coupe (258,000+ miles) - poor fuel efficiency, slow acceleration
11-30-2022
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2004 Honda Civic EX Coupe (258,000+ miles) - poor fuel efficiency, slow acceleration
Hello all, I'm new to this forum. I wanted to survey members here about my car's issues. Lately I've noticed my 2004 Honda Civic EX Coupe with 258,000+ miles has been suffering from poor fuel efficiency and slow acceleration. I have been regular with the oil changes. I used to get 29-30 mpg, now it's around 23-25. I used to get around 200-210 miles at half tank, now it has dwindled to 160-170. I also noticed acceleration problems. For example, coming from a stop or making a turn, the car struggles with accelerating. Top speed is not a problem though; I can still cruise it at freeway speed. Just the acceleration and the poor fuel efficiency is disturbing.
Any ideas where the problem might lie and what I can do?
Any ideas where the problem might lie and what I can do?
11-30-2022
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Re: 2004 Honda Civic EX Coupe (258,000+ miles) - poor fuel efficiency, slow accelerat
on the engine side, air filter and spark plugs could attribute to lowered fuel economy. Additionally, due to the acceleration issue, pesky vacuum leaks can cause a world of harder to diagnose acceleration issues. Timing could possibly be a factor, too, and considering you're at 258k, do you know the last time the timing belt and water pump were replaced? I think the manual calls for every 80-100k or so? I can't remember off the top of my head.
outside of the engine bay, tires, wheel bearings, and brake caliper lubrication (e.g. sticking brakes) could attribute as well.
Worst case scenario, head gasket leakage can have a hand in it, too, especially considering the D17 was prone to head gasket failure.
outside of the engine bay, tires, wheel bearings, and brake caliper lubrication (e.g. sticking brakes) could attribute as well.
Worst case scenario, head gasket leakage can have a hand in it, too, especially considering the D17 was prone to head gasket failure.
11-30-2022
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on the engine side, air filter and spark plugs could attribute to lowered fuel economy. Additionally, due to the acceleration issue, pesky vacuum leaks can cause a world of harder to diagnose acceleration issues. Timing could possibly be a factor, too, and considering you're at 258k, do you know the last time the timing belt and water pump were replaced? I think the manual calls for every 80-100k or so? I can't remember off the top of my head.
outside of the engine bay, tires, wheel bearings, and brake caliper lubrication (e.g. sticking brakes) could attribute as well.
Worst case scenario, head gasket leakage can have a hand in it, too, especially considering the D17 was prone to head gasket failure.
outside of the engine bay, tires, wheel bearings, and brake caliper lubrication (e.g. sticking brakes) could attribute as well.
Worst case scenario, head gasket leakage can have a hand in it, too, especially considering the D17 was prone to head gasket failure.
I'm concerned about what you said about vacuum leaks or head gasket failure. I don't recall any work being done on the engine itself, for 258k miles. All I've done were just maintenance stuff (oil changes, etc.).
The car still runs well, just really awful fuel economy and acceleration.
12-02-2022
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Rep Power: 339 Re: 2004 Honda Civic EX Coupe (258,000+ miles) - poor fuel efficiency, slow accelerat
when last o2 sensor was changed?
12-03-2022
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12-03-2022
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Rep Power: 339 Re: 2004 Honda Civic EX Coupe (258,000+ miles) - poor fuel efficiency, slow accelerat
sadly yours is a wide band sensor (up to 2002, they are cheaper narrow band ones), but a failing o2 sensor can make mileage drop down considerably while not triggering a CEL
used to be like 250 for the primary sensor
used to be like 250 for the primary sensor
12-05-2022
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Rep Power: 197 Re: 2004 Honda Civic EX Coupe (258,000+ miles) - poor fuel efficiency, slow accelerat
Might be worth using a scanner to check long and short fuel trim values. This is how much less/more fuel the ECU is adding based on the air/fuel ratio coming from the sensor.
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sdaidoji (12-05-2022)
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