Ecomodding an automatic '04 Civic Sedan

[Ecky]

Originally Posted by California98Civic

Maybe only the kind I have used have adhesive qualities. I can look some more. But it is not damage to the car, but ripping of the caulk if I have to remove the side skirts for any reason. The black caulk I used around the headlights ripped in ugly ways when I took the fixtures out to service them.

Sealing air gaps?

[mpg_numbers_guy]

Originally Posted by California98Civic

Maybe only the kind I have used have adhesive qualities. I can look some more. But it is not damage to the car, but ripping of the caulk if I have to remove the side skirts for any reason. The black caulk I used around the headlights ripped in ugly ways when I took the fixtures out to service them.

Ugly ways as in difficulty in removing or damage? Because who cares how the caulk looks after removing; we can just apply more.

-----------------------------------

I AM LOVING MY CIVIC.

Today's 3 trips averaged out to a whopping 49.5 MPG with one of the 3 trips being 52.5 MPG!!! Trips were 46.5 mpg (14.2 miles), 52.5 mpg (18.6 miles), and 47.8 mpg (5.7 miles), in order.

Not bad for an automatic with no engine modifications. Summer gas and warmer weather are definitely doing their part, but I can still tell the mods are helping too. Half the time I was literally cruising at 55-60+ mpg, and I had several stretches that were 70+ mpg despite being relatively flat and with only a slight, barely noticeable breeze. These mods are helping me coast SO much further too.

I need to redo my speed vs. MPG chart. That was in cold weather. But that would require demodding my vehicle, which I refuse to do until whenever I get around to improving the aesthetics of my mods.

Tank is now up to 45 MPG!

[19bonestock88]

Man, I go away for a couple days and you’re killing it! Nice work so far! You may get there first(50mpg tank) knowing that my 55mpg tank was purely a fluke... I’m proud to see such good progress

[mpg_numbers_guy]

Not sure about that...today's results proved otherwise...sort of.

Yesterday my car threw a check engine light, which tested out as P0135, which is the O2 sensor on bank 1 circuit 1 or something like that. Red flag since I know O2 failures are notorious for killing MPG.

Well yesterday's runs went fine as I posted. Today's runs didn't so much.
My first run, 5.0 miles, 44.2 MPG (record for that route).
My second run, 50.2 MPG (another record for that route).
Last trip, 5.7 miles...29.4 MPG.

Like, what the????

If this continues I'm going to be mad, and I will BIKE to wherever I need to go to get a replacement O2 sensor. My tank FE can't be ruined. It's already down to 44.2 (I averaged only 41.4 mpg today after that last trip).

[California98Civic]

Bank 1 O2 is the upstream one poking out of the exhaustmaniforld in fromt of the valve cover. There are methods for cleaning them. I have never tried. A replacement sensor for non v-tec-e engines is not very expensive. Yes, even without throwing a CEL it will mess up FE, since the ECU uses its signal to adjust AFR.

[mpg_numbers_guy]

Originally Posted by California98Civic

Bank 1 O2 is the upstream one poking out of the exhaustmaniforld in fromt of the valve cover. There are methods for cleaning them. I have never tried. A replacement sensor for non v-tec-e engines is not very expensive. Yes, even without throwing a CEL it will mess up FE, since the ECU uses its signal to adjust AFR.

Mine is VTEC (not VTEC-E) so would that one be more? If so, would putting a non-VTEC one work?

Just a wildcard thought...would it be possible when replacing it to "trick" the O2 sensor into running leaner?

[Ecky]

I believe the sensor is the same on all non-lean burn engines. It's the wide-band for lean burn engines which is really expensive.

My understanding of how it works (and someone correct me if I'm wrong) is that the upstream and downstream O2 sensors just check each other to see that they agree, in a car without lean burn. It's basically either a "yes" or a "no" as to whether or not the air fuel ratio is right, they can't determine what the exact AFR is. If one sensor goes bad or drifts, the two disagree and you get a CEL.

I'm seeing the replacement part as being about $18 on RockAuto, vs ~$130 for a wide band on engines that can do lean burn.

[westb87]

Originally Posted by Ecky

I believe the sensor is the same on all non-lean burn engines. It's the wide-band for lean burn engines which is really expensive.

My understanding of how it works (and someone correct me if I'm wrong) is that the upstream and downstream O2 sensors just check each other to see that they agree, in a car without lean burn. It's basically either a "yes" or a "no" as to whether or not the air fuel ratio is right, they can't determine what the exact AFR is. If one sensor goes bad or drifts, the two disagree and you get a CEL.

I'm seeing the replacement part as being about $18 on RockAuto, vs ~$130 for a wide band on engines that can do lean burn.

Can confirm. Just bought both O2 sensors for my 04 Civic D17A1. $130 for wideband and $70 for downstream (still haven't replaced the thing!). I bought them from Advanced Auto online and used their 20% off online coupon to order and then picked them up from the store the next day on my way home.

MPG_Guy: I know it doesn't help you AT ALL but those are the miles I'm seeing out of my Civic. I haven't replaced the downstream O2 sensor, but all else in the car emissions wise has been replaced/fixed/cleaned. I'm wondering if your sensors were stuck thinking the exhaust gases were rich, which caused your engine to run lean. Please keep us informed as you have been! I'm in the same boat as you right now, so if you find the solution please share! I'll do the same if I can get mine jumped up. What makes me think my problem could be that downstream O2 is that I'll see random jumps on the SG2 of my cruising MPG @ 50mph around 47mpg for about 1/4 mile or so and then it'll knock back down to my regular ~34mpg while maintaining the exact same load on the engine. I'll keep digging around in the old girl and I'll let you know if I find anything out! Keep on truckin' dude!

[westb87]

Originally Posted by mpg_numbers_guy

Mine is VTEC (not VTEC-E) so would that one be more? If so, would putting a non-VTEC one work?

Just a wildcard thought...would it be possible when replacing it to "trick" the O2 sensor into running leaner?

It's possible, but I wouldn't. You'll run the risk of burning valves. Fuel acts as an upper cylinder coolant when sprayed at the right A/F ratio into the combustion chamber. If you REALLY want to stay as lean as possible, get the car dyno tuned. Rather than having the shop tune for the most HP, they can lean the A/F mixture out across your fuel maps to keep you leaner than stoichiometric. Also, you could DIY with a megasquirt. I'd considered it, but this is my daily driver and I really can't afford to take her offline for anything more than a weekend as the wife needs the other vehicle to take our oldest son to school...at least for this year! He starts his new school that is within walking distance next year, so maybe next year I'll take a stab at "megasquirting" the Civic.

[mpg_numbers_guy]

Originally Posted by Ecky

I believe the sensor is the same on all non-lean burn engines. It's the wide-band for lean burn engines which is really expensive.

My understanding of how it works (and someone correct me if I'm wrong) is that the upstream and downstream O2 sensors just check each other to see that they agree, in a car without lean burn. It's basically either a "yes" or a "no" as to whether or not the air fuel ratio is right, they can't determine what the exact AFR is. If one sensor goes bad or drifts, the two disagree and you get a CEL.

I'm seeing the replacement part as being about $18 on RockAuto, vs ~$130 for a wide band on engines that can do lean burn.

That's good...how easy is it to install? I know that's kinda relative but...

Is it possible to work the other way and have the O2 sensor failing in that it runs leaner instead of richer?

Originally Posted by westb87

Can confirm. Just bought both O2 sensors for my 04 Civic D17A1. $130 for wideband and $70 for downstream (still haven't replaced the thing!). I bought them from Advanced Auto online and used their 20% off online coupon to order and then picked them up from the store the next day on my way home.

MPG_Guy: I know it doesn't help you AT ALL but those are the miles I'm seeing out of my Civic. I haven't replaced the downstream O2 sensor, but all else in the car emissions wise has been replaced/fixed/cleaned. I'm wondering if your sensors were stuck thinking the exhaust gases were rich, which caused your engine to run lean. Please keep us informed as you have been! I'm in the same boat as you right now, so if you find the solution please share! I'll do the same if I can get mine jumped up. What makes me think my problem could be that downstream O2 is that I'll see random jumps on the SG2 of my cruising MPG @ 50mph around 47mpg for about 1/4 mile or so and then it'll knock back down to my regular ~34mpg while maintaining the exact same load on the engine. I'll keep digging around in the old girl and I'll let you know if I find anything out! Keep on truckin' dude!

Well that route last night is known to get really bad mpgs (I never got above 30 before hypermiling) and I usually get in the 30s (I did get 45 once) but 29.4 is just terrible.

O2 sensor isn't dead yet; I managed 48.5 mpg for the first half of my driving today.

And yes my car does the same thing - one moment I'm cruising at 55 mpg and the next it jumps to 65 mpg without any change in elevation or anything. There's one stretch where I can average 70 mpg for about half a mile on completely flat terrain both ways.

Originally Posted by westb87

It's possible, but I wouldn't. You'll run the risk of burning valves. Fuel acts as an upper cylinder coolant when sprayed at the right A/F ratio into the combustion chamber. If you REALLY want to stay as lean as possible, get the car dyno tuned. Rather than having the shop tune for the most HP, they can lean the A/F mixture out across your fuel maps to keep you leaner than stoichiometric. Also, you could DIY with a megasquirt. I'd considered it, but this is my daily driver and I really can't afford to take her offline for anything more than a weekend as the wife needs the other vehicle to take our oldest son to school...at least for this year! He starts his new school that is within walking distance next year, so maybe next year I'll take a stab at "megasquirting" the Civic.

If only though lol.

That sounds complicated. I might consider that but for the most part I'm happy with the MPGs...except for those occasional bad trips...but 29.4 last night lol...I could go 80-85 mph and get that.

I drive my Civic about 25 miles daily so taking off the road for longer than a few hours isn't really practical.