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Discussion Starter #1
I'm trying to find out what's effecting my mpg the most of all my current problems. Right now im getting between 50-55mpg at most with heavy coasting, going no more then 55mph with some 45mph and 35mph cruising in 5th. Current problems are as follows.

Knockoff wheels 185/65R14 I think, they may be 75r14 or 85r14 I'll have to check Thursday.
HX rims.
O2 sensor is bad. Very, very bad.
Missing under engine paneling. Is there supposed to be paneling at the rear of the car?
Exhaust leak right under first cat. (I think a gasket is bad, part #12 on majestic Honda on the exhaust tab).
Passenger side motor mount and rear mount are shot.

I'm thinking the o2 sensor is the worst, then the knockoff tires, then the motor mounts when taking off, no? Would like some input on what I should repair first.

[Edit]: The o2 sensor is on its way to my house, and I already have the motor mounts. Just don't know how to install them.
 

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As a wild guess, because I changed my medication, is "tighten up the loose nut on the steering wheel".
Be patient, ICN will get you there yet.

HTH
Wilie
 

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Balto:
Here is something I just ran across that might help:
Number 1 02 sensor on AMAZON for $118.00.....NEW
HTH
Willie
 

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Make sure your plugs aren't loose like mine were, Balto.

I thought the motor mounts were bad in mine too, but I found out it only shook on start up from the plugs being so loose. Once they were torqued down the thing purrs like a kitten
 

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The tires are probably hurting you badly.

If you aren't getting into lean burn, that is hurting badly.

As Willie says, driving technique can hurt badly, but you have to have a good car before you can learn the technique.
 

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Yup, tires/wheels make a way bigger difference than you'd ever think.
 

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Concur with all of the above.

I would start with tire (weigh the cost/benefit ratio for your amount of driving)

Also consider:

- FUEL INJECTOR CLEANING/REBUILD. supposedly only like $75 for the three.

- CAT clog
 

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I'm trying to find out what's effecting my mpg the most of all my current problems. Right now im getting between 50-55mpg at most with heavy coasting, going no more then 55mph with some 45mph and 35mph cruising in 5th.

I get better mpg in 4th at 30-35 mph. The top two gears are both overdrive gears so 4th isn't all that bad.

I forgot, is your car a MT or CVT?


Knockoff wheels 185/65R14 I think, they may be 75r14 or 85r14 I'll have to check Thursday.
HX rims.

Get the OEM tires on the car and pickup 5 to 10% mpg.

O2 sensor is bad. Very, very bad.

BINGO! It's a requirement that the gas engine runs correctly to get good mpg.

Missing under engine paneling. Is there supposed to be paneling at the rear of the car?

At the speeds you mention the under paneling isn't as important as it ought to be at higher speeds. Yes there are some under panels towards the back of the car. Do a search on under paneling etc for pictures of all the panels.

Exhaust leak right under first cat. (I think a gasket is bad, part #12 on majestic Honda on the exhaust tab).

That could be upsetting the 2nd O2 sensor and causing you to think the 1st sensor is bad.

Passenger side motor mount and rear mount are shot.

Other then the engine falling out of the car that shouldn't affect your mpg once you are moving along (assuming the engine isn't hanging from the drive shafts :rolleyes:

I'm thinking the o2 sensor is the worst, then the knockoff tires, then the motor mounts when taking off, no? Would like some input on what I should repair first.

Fix the exhaust leak first. Undo the two lower spring loaded bolts at the bottom of the cat converter, then remove the top 3 bolts (after soaking them with penetrating oil for a day or so) THEN take off the bolt near the bottom of the cat converter holding it on to the bracket. You can lift the cat upwards out of the car after you disconnect the two O2 sensor connectors.

[Edit]: The o2 sensor is on its way to my house, and I already have the motor mounts. Just don't know how to install them.
On my car the exhaust pipe is in the way to remove the long bolt that holds the mount onto the bracket. Loosen the two rear motor mount bolts, unbolt the 4 bracket bolts from the engine, then remove the two mount mount bolts.

You might also try some injector cleaner. I've had good luck through the years with Techron cleaner.
 

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Pump up your tires to about 60 PSI and see if that has much of an impact. I agree with the above. Some people have said that any tire other than the original size, brand, etc will drop you 10 MPG.
 

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Discussion Starter #10
Well I'm a hypermiler so there really isn't a nut to adjust, but due to the lack of power right now I have to use a hell of a lot more throttle to move.

Tires aren't high on my list, due to the fact they are still in good condition, and I have more pressing things to fix.

Do I really have to remove the cat just to replace that gasket?
 

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Well I'm a hypermiler so there really isn't a nut to adjust, but due to the lack of power right now I have to use a hell of a lot more throttle to move.

Right. You need to fix your problems before hypermiling will get you anything.

Tires aren't high on my list, due to the fact they are still in good condition, and I have more pressing things to fix.

That's ok, as long as you understand that you aren't getting good performance with the wrong tires. I agree that you have other things to fix first. Just don't expect any really high MPG readings. The size is wrong, so your FCD isn't even giving you accurate readings. Your calculated readings are also wrong, unless you have used a GPS to calculate a distance correction factor.

Do I really have to remove the cat just to replace that gasket?
Maybe not, if there is enough movement to get the old donut out and the new one in. You'll need about an inch of clearance to be able to work in there. I can't do it on mine, but I'm not dealing with the stock front cat.
 

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If the O2 sensor is really not working, it could be the worse issue, but it's more of an unknown as to how it'll effect your MPGs when replaced. Also, I think the exhaust leak near the cat could possibly throw off the O2 sensors a little, so it's a related repair.

For me (just my impressions), the MPG gain from switching to OEM tires was about 5-10% (although I was switching from 15" rims also) and the lighter wheels improved acceleration noticeably. The front underbelly panel and the strakes in front of the front tires were worth about 3-8% for me with the higher percentage at higher speeds. The aero may be less important at the speeds you're driving right now, but it's also cheaper than new tires. The other thing to look into is the weight of your rims (you said they were Civic HX? are they 14s?), although this is less important than the tires.

Edit: checked your rim weight, 11.75 lbs. I think stock are 10.5?? so, the HX rims are reasonably light and not an issue.
 

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Like I said before Balto, my motor shook pretty bad until I torqued down my loose plugs! I was also getting crappy gas mileage before that. I'd at least check them out before you go spending money on something that may or may not help. Just pull the coils loose, throw a socket on them, and if they hand-turn in the hole you have found problem #1
 

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Discussion Starter #14
OK based on these suggestions I think I have a plan of attack.

On my way home, I'll stop by harbor freight and pick up a torque wrench.
Get one and torque spark plugs to proper torque.
Order the gasket I need for the exhaust leak.
See if I can do my motor mounts myself.
My o2 sensor should be here by Saturday, I'll put that in.
Save up for OEM tires.

Also, the HX rims are 14".
My spark plugs are NOT OEM, they are some autolite double platinum.
 

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O2 sensor, (lean burn)
tires, oem is THE ticket (air up some, even better)
plugs,
aero panels. (I got decent mpg without the front 3, adding KLR3CYL under panel added 4%)
practice, practice, practice.
 

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Discussion Starter #16
Went and grabbed a torque wrench today, and torqued the spark plugs to spec. The Damn car wants to go into lean burn every chance it gets! Lol. The shuddering in reverse is still there, but the car seems to be more stable. The P1164 is still there, still causing the annoying power loss.
 

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good to hear it, Balto! Figured that might be one of the issues

I know as far as mine goes, if it ever starts running crappy again, I'll grab my torque wrench before I do anything else!
 

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Discussion Starter #18
good to hear it, Balto! Figured that might be one of the issues

I know as far as mine goes, if it ever starts running crappy again, I'll grab my torque wrench before I do anything else!
Yea I thought I screwed the in tight enough when I took them out before, but I guess not because when I went to torque them the middle plug wasn't even hand tight.
 
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