93 Honda Civic VX horrible fuel economy

[Midcoasted]

I'm having the same terrible MPG problem. I just got 27 MPG city with an Si transmission. I got better mileage in my Del Sol with an Si engine and an auto lol. I just got my o2 sensor because I have the light. Tried to get a new cat but Bosal sold me one with a bolt pattern for a 96 I think. Canceled the new manifold from Honda.

I got the NGK 23400 and am looking into whether or not the cat/manifold from the 96 lx/hx will yield the exact same back pressure, 02 sensor readings/location, and mpgs as the stock 92-95 Vx/Cx set up?

I haven't put these parts on but here's my list.

New T-stat, all new hosing, new tbelt water pump and tensioner, all stock, but in the manufacturer's boxing. Also all new OEM rear shoes/springs from Honapartsdeals.com. I got the Denso stock plugs, would probably get the NGKs if I could again but the manual says this model Denso as well as the NGK's. New Denso Plug Wires, got a Beck and Arnley Distributor cap. I'm hoping I can solve my MPG woes at least into the upper 30s with the Si transmission, because the acceleration is way better when you want it to be and it feels fine in 5th doing 35. Also not interested in the stock rims. Just wanting like 40 MPGs really. I'm hopin the O2 sensor and new tstat will get me there because they both are faulty.

So back to my original question. Will the 96 cat/manifold set up yield the exact same results? And I don't mean to hi jack this thread sorry op.

[add|ct]

Originally Posted by *************

What's the first 8 digits of your VIN? As for not being able to access the grommet, if you can't access it, it's because parts are in the way. Just remove the parts that are in the way in order for you to get to it. In the case of the PCV valve in my civic, some people only removed the throttle cable bracket but because of my large hands, I had to remove the entire throttle body to get to the valve. However, what other people suggest is replacing the valve and grommet from underneath the car like you're doing an oil change. You might even go as far as to remove the breather box itself and while it's out, inspect it to see if there is any gunk in there.

If you don't replace the grommet now, it may crack in the future and will be even more difficult to remove than it is to remove today. Not something I'd put off. Also helpful to know how to remove it so that 60K miles from now, you'll know what to do.

2HGEH236

I may just have to wait until my next oil change(a month away) because I think the way you described may be slightly easier to remove the breather box, and I can examine the grommet up close, go ahead and replace it etc. My biggest concern is how much gunk or sludge may have formed there with a dysfunctional PCV valve.

[imzjustplayin]

Originally Posted by add|ct

2HGEH236

I may just have to wait until my next oil change(a month away) because I think the way you described may be slightly easier to remove the breather box, and I can examine the grommet up close, go ahead and replace it etc. My biggest concern is how much gunk or sludge may have formed there with a dysfunctional PCV valve.

Yeah, which is why taking out the whole breather box may be a good idea.. Oh and btw, you do in fact have a Canadian Model civic. Where do you live? If you don't live in Canada, I suggest disabling the daytime running lights because they use a lot of electricity and will definitely increase your fuel usage. As for your car having lean-burn, all 1992 civic VXs use a wideband O2 sensor, and I believe this is still true for Canadian models. However in 1993-1995, the civics that don't have lean-burn use a narrow band o2 sensor and the ones with lean-burn use a wide band o2 sensor. Maybe you can source yourself a 49 state ECU from a salvage yard and test it out to see if you do in fact get lean-burn when you previously did not. However I hope you tune up your car as much as you can before you do this change so that everybody knows for certain that going with a 49 state ECU will increase fuel economy and enable lean-burn over the Canadian ECU. If the Canadian ECU is capable of lean-burn, that too is useful information.

[add|ct]

I don't know if it is or it isn't capable of lean-burn based on the computer(haven't checked to see the numbers on it yet) but I sure 'thought' I felt the lean-burn while driving. It took replacing the LAF sensor, which made the throttle much more user-friendly, where as I had to replace the original(that had 230k miles on it) to get rid of the code 48. Since, the car drove much better and I could apply less gas than before with a restoring of power lost through the mid-range previously in the higher gears.

This car was sold originally brand new from a Honda dealer outside of metro-Atlanta, GA. I live in Atlanta currently, and purchased the car from an old lady moving to Sweden.

PS: I suppose I don't have 'daytime' self-running lights, I was thinking of the side lamps/park lights etc., but I believe this car had a previous wreck so it may have had them originally?

[imzjustplayin]

Originally Posted by add|ct

I don't know if it is or it isn't capable of lean-burn based on the computer(haven't checked to see the numbers on it yet) but I sure 'thought' I felt the lean-burn while driving. It took replacing the LAF sensor, which made the throttle much more user-friendly, where as I had to replace the original(that had 230k miles on it) to get rid of the code 48. Since, the car drove much better and I could apply less gas than before with a restoring of power lost through the mid-range previously in the higher gears.

This car was sold originally brand new from a Honda dealer outside of metro-Atlanta, GA. I live in Atlanta currently, and purchased the car from an old lady moving to Sweden.

PS: I suppose I don't have 'daytime' self-running lights, I was thinking of the side lamps/park lights etc., but I believe this car had a previous wreck so it may have had them originally?

I'm not really sure how a Canadian model car can be sold as "new" in the United States... When I say you have daytime running lamps, with the car running, if you release the parking brake (parking brake down), and look around the front, are the headlights on or not? If you have the helms manual, it should tell you where the daytime running lights control module is. It's up under the dash on the left hand side. There shouldn't be any lights on during the day if your turn stick is set everything to off but if you've got some lights running when the parking brake is down (released), maybe you're right, it was in an accident or some kid re-wired the system..

[add|ct]

It's really weird. There is still the faded Honda dealer logo on the back and I'm fairly certain the car doesn't have daytime running lights, but never really checked the way you described.

...I'll read the manual!

[imzjustplayin]

Originally Posted by add|ct

It's really weird. There is still the faded Honda dealer logo on the back and I'm fairly certain the car doesn't have daytime running lights, but never really checked the way you described.

...I'll read the manual!

The easiest way I suppose is to try driving the car at night without trying to turn on the headlights. On the FJ cruiser I have, it has daytime running lights that use the actual headlights, no dimming or anything and sometimes at night, I'll forget that I had not turned on the headlights. Anyway I disabled the daytime running lights in the FJ because I didn't want to prematurely burn out the bulbs and waste gasoline.

[add|ct]

No daytime running lights for us so it seems, but the car does have the shift indicator and the 'check' engine light looks like the one pictured for the US version, not blank as per the diagram in the owner's manual.

...as for the PCV valve replacement so far the car drives better. It's easier to keep the speed constant in 5th gear where sometimes the car likes to either have more gas/less gas and starts feeling 'choked', another reason I believe it's lean-burn.

[imzjustplayin]

Originally Posted by add|ct

No daytime running lights for us so it seems, but the car does have the shift indicator and the 'check' engine light looks like the one pictured for the US version, not blank as per the diagram in the owner's manual.

...as for the PCV valve replacement so far the car drives better. It's easier to keep the speed constant in 5th gear where sometimes the car likes to either have more gas/less gas and starts feeling 'choked', another reason I believe it's lean-burn.

Did you clean the IACV? My civic was having that issue too and the majority of the issue was caused by a sticky/stuck IACV. (Idle Air Control Valve) Clean the EGR? A lot of these suggestions were made in this very thread which you may need to read from the beginning again. I think I should create a FAQ to tuning up these cars.

[benfrogg]

*************-
If you do a write up, link it here. I think it's a good idea.

Addlct-
Did you tear off the breather box and clean it? I want to know how bad that thing was crudded up. It it was bad, I'll take the time to clean mine ASAP. If not, I'll wait till the next oil change.
B