Weird MPG problem

My daughter just got an 08 Honda Fit Sport to replace her 07 Fit Sport that was totaled when she got rear ended at a stop Memorial Day weekend. Both cars are automatic, the new one has 150k on it vs. 250k on her old one. 
 

For some reason her "new" car is only averaging around 20mpg(calculated) vs. 30+ she saw in her old one. Both cars are automatics. I swapped over her new tires from her old car, as well as the plugs & coil packs we just installed in March, but it didn't improve the mileage. 
 

I've driven the car & it feels fine, though might accelerate just a bit slower than her old one. There are no codes, it drives & idles fine - and I even compared the exhaust sound & smell between both cars. I couldn't hear/see/smell any difference between the two. 
 

The wheel bearings all feel fine, they torn freely but there's no wobble. I'm going to have her check their temps after the next drive across town. I checked the air filter, it's not new but definitely isn't plugged either. 
 

So what could cause a ~30% loss of mpg without triggering any codes, or displaying any obvious symptoms?

First thing I would do is pull a cable off the battery, turn on the dome light switch, and leave it overnight.  Reconnect and try again.  Most ECMs learn.  For instance, if the previous owner always accelerated hard it may have learned to back off the WOT enrichment to save the catalyst.  If the previous owner always drove it for short commutes when it was cold, it may have learned to lean out sooner on the CTS map.  If they always did a lot of long-distance driving it may have made changes to cruise mixture based on O2 sensor data.

Wipe it's memory and let it re-learn HER inputs.

Otherwise, O2 sensors, partially plugged catalyst, different tires, parking brake dragging, or a combination of some of the above.  But yeah... 20mpg from a Fit is not kosher.  I can almost get that with my 94 Branger 4x4 with 32" tires if I drive like it's Sunday.

Oooh... something else as I re-read.  08 started new EPA emissions regs.  It certainly shouldn't cause a 30% difference, but if (for instance) they lowered NOx and Honda responded by fattening the fuel curve and re-designing the EGR, it could certainly have an affect.  Not 30%, but don't expect the same MPGs as the old one.

07 EPA ratings were 33/38.  08 ratings were 28/34.  Something happened when the new EPA limits became mandatory.

In reply to Curtis73 (Forum Supporter) :

Wow good to know about the EPA changes!

I drove it again tonight - harder, since my daughter owns it & the seller wasn't in the car :)

I discovered a couple things. First I checked the wheels & found the RF to be quite a bit hotter than the rest. I did a couple panic stops & noticed it's pulling to the left, so I think the RF caliper might be dragging & the pads may be glazed over.

There's also a noise from one of the rear wheels. We swapped her tires onto the car, so I'm guessing a wheel bearing, though it wasn't generating enough heat to notice through the wheel.

Lastly I noticed it felt a little darty anytime I turned the steering wheel off-center. I checked the front alignments with a couple 2x4's (in the rain), but if my measurements are anywhere close to reality there's about 3/8" toe-out up front. I'm guessing that's most of her MPG loss. 

Curtis73 (Forum Supporter) said:

Oooh... something else as I re-read.  08 started new EPA emissions regs.  It certainly shouldn't cause a 30% difference, but if (for instance) they lowered NOx and Honda responded by fattening the fuel curve and re-designing the EGR, it could certainly have an affect.  Not 30%, but don't expect the same MPGs as the old one.

07 EPA ratings were 33/38.  08 ratings were 28/34.  Something happened when the new EPA limits became mandatory.

My understanding is that the EPA simply changed how they measured fuel economy in 2008. So the mpg on the window stickers changed significantly, but the real world mpg of the cars themselves didn't.

I had a similar issue pop up on my 12' JSW TDi, 6 months after I changed the front brake pads.  Occasionally I'd get a whiff of carbon smell, a mild vibration and a decrease in MPG from 40 highway to 30.  Right front wheel was radiating a LOT of heat.  I gave this a few days and replaced the right front caliper, thinking it was intermittently seizing and media blasted all the rust off if the pad carrier.  Problem solved. 

I hope that's helpful. 

Driven5 said:

Curtis73 (Forum Supporter) said:

Oooh... something else as I re-read.  08 started new EPA emissions regs.  It certainly shouldn't cause a 30% difference, but if (for instance) they lowered NOx and Honda responded by fattening the fuel curve and re-designing the EGR, it could certainly have an affect.  Not 30%, but don't expect the same MPGs as the old one.

07 EPA ratings were 33/38.  08 ratings were 28/34.  Something happened when the new EPA limits became mandatory.

My understanding is that the EPA simply changed how they measured fuel economy in 2008. So the mpg on the window stickers changed significantly, but the real world mpg of the cars themselves didn't.

They also instituted new regs.  Not a big change, but different.

Edit:  Maybe nevermind.  2008 regs were primarily diesel changes.  Tighter PM and NOx limits, hence DPFs and Urea

No major change in real world fuel economy between 07 and 08

Make sure the front brakes are not binding.  Pads rusted in place, caliper pins stuck, common issues that cause problems.

How's the alignment?  As in, has it been on an alignment rack?

In reply to Pete. (l33t FS) :

She just got it, so no idea, but my tape measure & a couple 2x4s shows it has about 3/8" front toe out. 

In reply to Pete Gossett (Forum Supporter) :

Definitely set up an appointment with your favorite alignment shop.

In reply to Pete. (l33t FS) :

I haven't found one yet, but the one I did on the Miata turned out ok. And I figure it's unlikely I'll make her car worse. She's planning on dropping it off while they're out of town this weekend, so I'll get the alignment closer, check the RF brake situation & see if I can identify the noise I heard from one of the rear wheels. 

there's no way in hell short of tracking a fit you should see 20 MPG.

I get 12 MPG ON TRACK, so my tanks with sessions are down around 20, but the automatic has taller gearing and should definitely be seeing 30+mpg average.. even around town..

 

I finally had time to work on it today. I got the front as close to zero toe as I can with a tape measure, a couple 2x4s and a helper. It's definitely much closer than it was. 
 

I found the lower guide pin on the driver's side front caliper was stuck all the way in, but once I popped it out it seemed to slide fine. I'll monitor it though. 
 

The passenger side front caliper seemed to be really tight on the rotor. I opened the reservoir & used a clamp to compress the piston, but I have a hunch I'll be replacing it & possibly the hose. The pads all look brand new though. 
 

I couldn't track down the noise in the rear. It sounds kinda like a rock in the tread(I checked, it isn't) but comes on pretty suddenly around 45mph. The wheels both turn freely, don't wobble, don't get hot, and feel smooth when I turn them slowly by hand. I'll continue to monitor that situation too. 

Sounds like your on the right track.  Service and lube up them brake pins and make sure the pads can slide freely in the shims.  Many times Ive had to take a whizz wheel to pads because they have too much powdercoating on them causing them to bind.

Wouldn't hurt to do a full brake fluid flush while your at it anyways.