What am I missing here? Diminishing fuel economy on a Civic HX
03-20-2013, 11:18 AM
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What am I missing here? Diminishing fuel economy on a Civic HX
Hi! I have a 1997 Honda Civic HX. Car has apporx 183,500 miles. Completely stock except for the exhaust (original rusted out). It still has the factory cat. For the past seven months or so I have a been getting diminishing fuel milage. Prior to the change I had been getting 36-38 mpg. Now I'm down 30-32. My car should be getting 40-42. What I have done:
New NGK plugs
New NGK spark plug wires
New NGK O2 sensor (5 wire wideband)
New Dist. Cap
Re-set valve lash
Checked egr valve and egr plenum
Checked tips of injectors (had to remove to look @ plenum and tips were good and clean)
Ran three tanks of techron fuel system cleaner
The car starts and runs like it always has for the last 70,000 miles that I've had it. I started out with my factory hx wheels but for the last four months I have been running a set of blades (stock crx rims) with my winter tires. The engine gets up to temp within two to three miles of driving. I also park the car in my garage which is always above freezing (usually around 50 or so because my wood stove/boiler is next to it). What am I missing to check here??? If I get a warmer day I'm going to check the valve lash again but other than that everything seems to check out. The only other thing that I could think of is if the coil is getting weak giving a weak spark??? Help me out here....
thanks for your time!
New NGK plugs
New NGK spark plug wires
New NGK O2 sensor (5 wire wideband)
New Dist. Cap
Re-set valve lash
Checked egr valve and egr plenum
Checked tips of injectors (had to remove to look @ plenum and tips were good and clean)
Ran three tanks of techron fuel system cleaner
The car starts and runs like it always has for the last 70,000 miles that I've had it. I started out with my factory hx wheels but for the last four months I have been running a set of blades (stock crx rims) with my winter tires. The engine gets up to temp within two to three miles of driving. I also park the car in my garage which is always above freezing (usually around 50 or so because my wood stove/boiler is next to it). What am I missing to check here??? If I get a warmer day I'm going to check the valve lash again but other than that everything seems to check out. The only other thing that I could think of is if the coil is getting weak giving a weak spark??? Help me out here....
thanks for your time!
Last edited by deschlong; 03-20-2013 at 11:55 AM. Reason: Clarified topic in title, as per forum rules.
03-20-2013, 11:23 AM
#2
Re: What am I missing here?
Keep in mind that at 183,xxx that engine isnt running as good as it once was. When they set the estimated mpgs for motors thats when they are brand new. The motor has been through a lot buddy.
03-20-2013, 11:45 AM
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Re: What am I missing here?
few things I forgot:
-When I put my winter wheels on I checked the brakes and the front brakes were not dragging and pins are well greased/move back and freely and the rears do not drag.
-When I changed the primary 02 sensor I looked in the cat and it seemed pretty clean/very little carbon
-New fuel filter
-When I put my winter wheels on I checked the brakes and the front brakes were not dragging and pins are well greased/move back and freely and the rears do not drag.
-When I changed the primary 02 sensor I looked in the cat and it seemed pretty clean/very little carbon
-New fuel filter
03-20-2013, 11:47 AM
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Re: What am I missing here?
I'm going to get a can of throttle body cleaner next and see if I can clean up the intake a little. Is there anything that I missing that I should check? Also tranny oil has about 10,000 miles on it. I'm sure I'm missing something here. I wouldn't be disappointed if my car had 300,000 miles but 183 should just be getting broke in good lol!
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03-20-2013, 12:16 PM
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Re: What am I missing here? Diminishing fuel economy on a Civic HX
Thanks,
Robert
03-20-2013, 01:14 PM
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Re: What am I missing here? Diminishing fuel economy on a Civic HX
Not sure on the pcv, bought new valve but hadn't installed yet. May be a dumb question but where would it be a a y5? I don't have my book infront of me and I haven't had a chance to look into changing it yet as I've been working, cutting firewood, and hauling hay/straw.
Thanks,
Robert
Thanks,
Robert
03-20-2013, 01:20 PM
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Re: What am I missing here? Diminishing fuel economy on a Civic HX
no more than 30,000 miles ago. Probably closer to twenty. I'll look closer tomorrow after I get home. I got a new air filter but haven't put in b/c new one seems clean.
03-20-2013, 01:54 PM
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Re: What am I missing here? Diminishing fuel economy on a Civic HX
change from 11lb wheels 15lb ones and difference in tire overall circumference and weight?
change in driving conditions? i.e more city less highway? foot got heavy?
change in driving conditions? i.e more city less highway? foot got heavy?
03-20-2013, 02:18 PM
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Re: What am I missing here? Diminishing fuel economy on a Civic HX
03-20-2013, 04:33 PM
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Re: What am I missing here? Diminishing fuel economy on a Civic HX
Driving habits same-I drive pretty light footed with little to no spirited driving.
Tire pressure is 32-35
Unless the "winter" gasoline was put to use early and is garbage then I really can't say much is different. Even before when I'd run my 17's the year before I would get 37.5 almost every tank. Driving conditions are the same. I drive 13 miles one way to work with light to mild traffic that consists of two stop signs and four traffic lights that are green atleast half the time. And its a state route that I travel 55-70 mph depending on traffic and weather.
03-20-2013, 05:00 PM
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Re: What am I missing here? Diminishing fuel economy on a Civic HX
03-20-2013, 07:14 PM
#18
Re: What am I missing here? Diminishing fuel economy on a Civic HX
Driving habits same-I drive pretty light footed with little to no spirited driving.
Tire pressure is 32-35
Unless the "winter" gasoline was put to use early and is garbage then I really can't say much is different. Even before when I'd run my 17's the year before I would get 37.5 almost every tank. Driving conditions are the same. I drive 13 miles one way to work with light to mild traffic that consists of two stop signs and four traffic lights that are green atleast half the time. And its a state route that I travel 55-70 mph depending on traffic and weather.
Tire pressure is 32-35
Unless the "winter" gasoline was put to use early and is garbage then I really can't say much is different. Even before when I'd run my 17's the year before I would get 37.5 almost every tank. Driving conditions are the same. I drive 13 miles one way to work with light to mild traffic that consists of two stop signs and four traffic lights that are green atleast half the time. And its a state route that I travel 55-70 mph depending on traffic and weather.
03-20-2013, 11:07 PM
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Re: What am I missing here? Diminishing fuel economy on a Civic HX
Your car sounds like you have done all the right things.
If your tires are up tp pressure and you realy are a light foot driver then its the winter gass.
I never get the same gas mileage in the winter.
I have a 99 SI and i was getting 700km a tank or about 39mpg. In the winter I am lucky to get 600km
The only other thing you may try is sea foam cleaner.
I does work
My motor is stock as well did all the right things spark plugs , wires, filter stock cat and only after doing the sea foam in the intake and the oil thats when my milage went up to 39 MPG. in the summer.
oh and i have 330km on my car
If your tires are up tp pressure and you realy are a light foot driver then its the winter gass.
I never get the same gas mileage in the winter.
I have a 99 SI and i was getting 700km a tank or about 39mpg. In the winter I am lucky to get 600km
The only other thing you may try is sea foam cleaner.
I does work
My motor is stock as well did all the right things spark plugs , wires, filter stock cat and only after doing the sea foam in the intake and the oil thats when my milage went up to 39 MPG. in the summer.
oh and i have 330km on my car
Last edited by Lateapex89; 03-20-2013 at 11:08 PM. Reason: Shit I just noticed your from the states, do you get winter where you are?
03-21-2013, 05:09 PM
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Re: What am I missing here? Diminishing fuel economy on a Civic HX
I did hear a lot of complaining about the winter blend in the upper new England states making everyones cars run like crap. Local News wise up there anyways.
Last edited by TOP91; 03-22-2013 at 03:30 PM.
03-21-2013, 06:42 PM
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Re: What am I missing here? Diminishing fuel economy on a Civic HX
have you cleaned the IACV? also check the tension on your throttle cable. if it aint tight you could be giving it more gas to compensate for the slack and k=just not realizing it.. might not be a fix but if its loose and you tighten it you WILL notice a difference. i know i did..
03-21-2013, 06:50 PM
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Re: What am I missing here? Diminishing fuel economy on a Civic HX
Hx wheels are very light- someone mentioned this.
Adjusted timing? Also, have you changed trans oil lately? Lot of friction going on inside there...
Adjusted timing? Also, have you changed trans oil lately? Lot of friction going on inside there...
03-22-2013, 05:43 PM
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Re: What am I missing here? Diminishing fuel economy on a Civic HX
have you cleaned the IACV? also check the tension on your throttle cable. if it aint tight you could be giving it more gas to compensate for the slack and k=just not realizing it.. might not be a fix but if its loose and you tighten it you WILL notice a difference. i know i did..
As stated before, the car starts idles runs and drives normal but if I get a chance this weekend Ill try to clean the IACV and change the pcv valve.
Thanks!
Robert