Ecomodding an automatic '04 Civic Sedan

[mpg_numbers_guy]

Been getting a crap ton of rain here lately and my duct tape covered cardboard mods are still holding up perfectly. Still haven't gotten around to the wheel skirt project due my busy schedule, but P&G is helping MPG a lot....my previous best trip of 52.5 MPG over 18.6 miles was beat yesterday with 52.8 MPG over a trip of only 5.7 miles.

Trip averages prior to P&G were around 45, now they're around 46, but I'm still learning how to P&G for maximum efficiency so it's exact benefit can't be quantified yet.

50 is looking more reasonable again once I get around to putting these next mods on. Problem is, I'm almost out of painters tape and it's $10 for another roll. Not expensive of course, but ROI...

Going to replace the O2 sensor here soon hopefully. Haven't noticed a drop in MPG, but hey, it can't hurt.

Do bad O2 sensors gradually decrease mileage or is it a sudden drop?

[deluxx]

Originally Posted by mpg_numbers_guy

painters tape

I would invest in gorilla tape.

Originally Posted by mpg_numbers_guy

O2 Sensor

If it ain't broke don't fix it!

[California98Civic]

What makes u say ur O2 is bad? Also, before replacing it, consider cleaning it with gasoline. Search google. I am about to try it for the first time. But I got the CEL P0420, which indicates trouble in the secondary O2 or the CAT.

[mpg_numbers_guy]

Originally Posted by deluxx

I would invest in gorilla tape.

Gorilla tape and duct tape can potentially harm your car's paint in the heat. Painter's tape is safe and so far has held on perfectly well. I have covered the painters tape with silver duct tape to hide the blue color.

Originally Posted by deluxx

If it ain't broke don't fix it!

Originally Posted by California98Civic

What makes u say ur O2 is bad? Also, before replacing it, consider cleaning it with gasoline. Search google. I am about to try it for the first time. But I got the CEL P0420, which indicates trouble in the secondary O2 or the CAT.

My check engine light is on, and by scanning the error code it's pointing to the O2 sensor on bank 1. EDIT: Error code P0135 I think??

MPGs haven't dropped yet...in fact I made a HUGE new MPG record today - coming home from work tonight I scored 58.2 MPG doing P&G 31 mph > 39 mph > 31 mph, repeatedly. No traffic allowed me to use maximum hypermiling skills. Torque showed a high of 59.6 at one point, but that was before the final hill...and the last half mile of the trip I get 55 mpg, which has been higher than my trip averages until now, but which pulled me down too here. No wind, decent outside temperature of 62F (16.7C). This gave me my first day average of above 50 MPG (50.7 MPG). P&G really does help...when traffic permits...which it did tonight.

[California98Civic]

Originally Posted by mpg_numbers_guy

... My check engine light is on, and by scanning the error code it's pointing to the O2 sensor on bank 1. EDIT: Error code P0135 I think?? MPGs haven't dropped yet...in fact I made a HUGE new MPG record today - ...

So if that is the code, then your upstream (top) o2 sensor is not heating quickly enough or properly. If that is the code and the failure, then your MPGs should drop and badly because that is the sensor that feeds data for the ECU to set AFR. Without good, quick data and good heating, the AFR will run rich, probably in open loop. So if this is the proper code, then I think you have a mild--even intermittent--O2 failure, which is a prime candidate for cleaning the O2 and saving some bucks. Clear the code to shut of the CEL after you double check which one it is and record it. I would not be surprised if it does not come back right away. Then clean both sensors. That's my thoughts.

[mpg_numbers_guy]

Originally Posted by California98Civic

So if that is the code, then your upstream (top) o2 sensor is not heating quickly enough or properly. If that is the code and the failure, then your MPGs should drop and badly because that is the sensor that feeds data for the ECU to set AFR. Without good, quick data and good heating, the AFR will run rich, probably in open loop. So if this is the proper code, then I think you have a mild--even intermittent--O2 failure, which is a prime candidate for cleaning the O2 and saving some bucks. Clear the code to shut of the CEL after you double check which one it is and record it. I would not be surprised if it does not come back right away. Then clean both sensors. That's my thoughts.

How bad would they be? Would it be possible for it to go bad and still get these MPGs by hypermiling, but get even better after replacing/cleaning?

RPMs are consistently dropping out of "warm up mode" at an engine coolant temp of 71C.

Would it be possible for something to throw the error without it existing? I reset it a while back and it returned about 5-10 seconds after starting my car.

EDIT: and is it possible to ruin the O2 sensor by cleaning it?

[mpg_numbers_guy]

Built my tail extension prototype and have my second attempt at side skirts ready, now I just need to go to the store and pick up some painter's tape.

But looks like 50 MPG is here to stay for the most part...had 4 days in a row averaging above 50 MPG and yesterday was just a hair under (didn't drive today).

We'll see how these numbers hold up when I fill up in a month.

[19bonestock88]

Sounds good! Got any pics?

[California98Civic]

Originally Posted by mpg_numbers_guy

How bad would they be? Would it be possible for it to go bad and still get these MPGs by hypermiling, but get even better after replacing/cleaning?

RPMs are consistently dropping out of "warm up mode" at an engine coolant temp of 71C.

Would it be possible for something to throw the error without it existing? I reset it a while back and it returned about 5-10 seconds after starting my car.

EDIT: and is it possible to ruin the O2 sensor by cleaning it?

I think whether cleaning ruins o2 sensors is a matter of how you do it. Do what others have done with success and take it easy and it should be fine. I think if you have an intermittent failure it will come back, sooner or later, sometimes sooner, sometimes later. I do think CELs can get set off in error. It is just voltage fluctuations that communicate the messages to the ECU. I think old machines learn new tricks.

I got my P0420 again tonight, despite cleaning the sensors the other day. My next move is clean the CAT itself, since I now can eliminate the O2 sensor as the source. Science!

[mpg_numbers_guy]

Originally Posted by 19bonestock88

Sounds good! Got any pics?

Not yet, the wheel skirts are the same as the old ones just trimmed a bit. And the tail extension hasn't been coated in duct tape yet so it'a basically just a piece of cardboard. It extends about 8 inches (I think?) out.

Problem is, it's been raining this whole week...and tomorrow I'm busy the whole day just like today...and on Wednesday we leave and I'm out of the country for like almost 4 weeks.

Originally Posted by California98Civic

I think whether cleaning ruins o2 sensors is a matter of how you do it. Do what others have done with success and take it easy and it should be fine. I think if you have an intermittent failure it will come back, sooner or later, sometimes sooner, sometimes later. I do think CELs can get set off in error. It is just voltage fluctuations that communicate the messages to the ECU. I think old machines learn new tricks.

I got my P0420 again tonight, despite cleaning the sensors the other day. My next move is clean the CAT itself, since I now can eliminate the O2 sensor as the source. Science!

It still doesn't make sense how the error code persists despite resetting it a couple times, and yet my MPGs are just fine. These last seven days have averaged above 50 MPG, and my tank is supposedly up to 46.9 MPG currently based on the Torque app. This is my first full tank monitored with Torque so idk how accurate is, but it seems to be fairly close compared to the fuel tank. I still have another 140 or so miles before the low fuel light turns on, and since I'll only be going 20-21 more miles before leaving, I won't know the outcome of this tank until mid June.

The suspense is killing me. That and the CEL lol.