Wrona

So i've noticed my civic has been getting sh*tty mileage for a while now

Replaced cap and rotor (orileys) 8k miles ago (I was going to get OEM but the dealership was closed and i needed it because my cap was broken)
Coolant bled
Plugs changed less than a 1k miles ago
oil changed 1400 miles ago (Penzoil 5W30) + WIX filter
PCV valve (OEM Honda) 13K miles ago
New Breather Hose replaced the filter i had on there
Air filter looks pretty clean its a Spectre cone filter (didnt have a stock airbox when i swapped the y8 mani on it)
cleaned the throttlebody and sensors with carb cleaner
New plug wires 8k miles ago (Denso)
Changed fuel filter (Fram) 13k miles ago

I dont know what it could be i added HEET recently because the cold was harsh and i was just making sure there was no water in my fuel system but this MPG problem has been happening before this i tried BG44k like 4K miles ago and it didn't help usually does

I think it could be the Fram Fuel Filter since i added fuel additives like Heet and BG44K but i don't know i got the fuel filter for free I was thinking about changing it out for an OEM but decided to ask first

There is no CEL it does work because i had it on a while back for o2 Heater circut but that fixed itself somehow

I do think that this could also be the culprit in my MPG

I am going to be doing a Valve adjustment here soon but i don't think it would effect it that badly

Former User

What spark plugs are you using? Are they gapped properly?

Have you checked the ignition timing with a timing gun?

Wrona

NGK Copper plugs gapped to .044 and no i have not

fleabag

Clean ALL electrical grounds so that every metal part used in the ground is shiny, so the bolts, the washers attached the bolts, the threads, the eyelits on the ground cable, the gap between the washer and bolt, the hole the bolt screws in are all clean and shiny. FYI, don't scrape any paint off! A dirty electrical ground can weaken the signal to the ECU causing it to temporarily run in a mode where it discards a sensor's output and interpolates the data for it. Consult the Helms manual for the location of the electrical grounds.

Take off the heat shield and see if you have a cracked exhaust manifold b/c a cracked manifold can cause the o2 sensor to act improperly.

If you can, try to get an OBD-II reader that will tell you engine specs such as coolant temperature and engine RPM. You want to make sure your car is idling at stock 670rpm +/- 50rpm and that your thermostat is opening and closing at the right times.

I would also replace all vacuum hoses that look old, especially the one for the PCV valve. When you take off the hose and look into the hole, pinch the tip of the hose and if you see it making little cracks around the edge, then the hose is bad. Did you replace the grommet when you put in the new PCV valve? Did you test the PCV valve to make sure that it operates as a check valve? To test the valve, take it out, clean the part that goes into the engine, look up, put it into your mouth, exhale and inhale. You should be able to easily exhale but not inhale. If you're able to inhale as easily as you exhale, then the valve is defective (it's a check valve).

Pre95

Clogged EGR valve?

sde780

I'd bet the o2 sensor is affecting your gas mileage. What are you getting? I got a solid 30-35mpg in town in my D16Y8 before going turbo

Wrona

the Y7 doesnt have an EGR valve


well let me put it this way i i put in 5 galons yesterday and today im almost empty and i went about 120 miles so about 24 but even when i put in a full gas tank i loose it like 2 days later and my driving habbits are not that bad i shift at 3k rpm

fleabag

Did your problems get worse after you replaced your distributor or has nothing changed despite all of the things you mentioned you did in the original post?

grumblemarc

iTrader: (4)

Try it with 2 full tanks and compare mileage then.

Former User

Check the ignition timing.

motegicivic

The best way to determine mileage, is to fill it up, reset the odometer. Go back fill up again and see what the gallons are off the pump, take the odometer reading and divide by gallons used.

Use this as a bench mark.

Wrona

after i changed my distributor cap and rotor things got better for a couple thousand miles i could fill up 10 dollars and it would last me like 4 days with my driving and that was when gas prices were higher i filled up for 12 at 2.99 per gallon and its literally almost all gone i know that to determine MPG i should do the full tank of gas i used to do that all the time but i dont think my gas should be gone so quickly especially since i dont drive like a idiot

Ron will do i will get it checked out one point this week what would cause ignition timing to shift though the distributor has never been touched

also another thing i noticed my motor shakes a lot at idle could be air still in the coolant im going to re bleed today again it seems no matter how long i bleed it there is still air

motegicivic

I am getting the shake at idle too, I am trying to bleed mine as well. I am wondering if it is winter gas, sometimes there is more ethanol makes the car run like crap.

I would do a compression check, see the condition of the engine.

Wrona

Yeah they do use winter blend but it didn't go by that fast last year and winter just started idk like ron said im going to check my ignition timing

my compression is good 155psi across the board

sde780

Lol you can't judge your gas mileage by the gas gauge.

1.Fill up your car today until the pump clicks to a stop, don't top it off
2. Reset the trip meter
3. Drive around 200 miles or until your gauge goes below the middle
4. Fill up again until the pump clicks to a stop, don't top it off
5. Take the number of miles logged on the trip meter divided by the amount of gas displayed on the gas pump = MPG

On my CRX I drive it until E and it only takes 8 gallons to fill up, which means the gauge is very inaccurate. I drove 50 miles and it's at the middle already. Using my method I still get around 30 mpg in town.

Wrona

wasnt judging by the gauge i was judging by the fact that i had to get gas from my emergency stash in the trunk cause my car wouldnt start it
would just bog down

i usually look at the amount of miles driven not the gauge ill try that method you mentioned

mikesanto70

WRONA,

What do you consider crappy mileage, i did not see what you said you were getting for mpg., so what are you getting?

mikesanto70

I have a 96' DX Hatch w/ a D16Y7 w/ an auto and I'm getting 29-30 in mixed city/hwy. I thought I should be doing a little better than 29 since its only got 76k. mi. Is that about normal for an EK Hatch w/ a D16Y7 and a slush box!!! I want to do a highway trip before I do my B20 swap to see what it can really do on long flat AZ highways. ****, my 98' Ford Crown Vic w/ a 4.6 & 165k well maintained miles on a flat stretch from Phoenix to the state border in Blythe CA in the summer w/ A/C on and doing 75 w/ cruise on got 30 mpg. I ****in couldn't believe it, but it was 100% accurate because I filled in Phoenix and when I got to blythe it only took 5 gal. But as soon as I got into hilly terrain in CA, my average dropped to 24!!

zay

agreed

Wrona

changed the fuel filter and everything went back to normal...

driftn_silvia

did you change it back to the oem or got another fram fuel filter?

dishjuarez

How many mpg are getting now?

chief_13

i have a 92 civic eg with mini me swap and get very bad gas milage any feedback would b great

furious94ls

Notice how the OP gave full details on the car he had, and the maintainance that was performed? How are we to know what to tell you to do if you give us no info? We aren't mind readers.

teo032

how do you know that we're not mind readers?? I'm reading yours right now!