Last post on Mar 25, 2013 at 6:51 PM
You are in the Honda Civic Hybrid
What is this discussion about?
Honda Civic, Hybrid Cars, Fuel Efficiency (MPG), Sedan
#499 of 540 Re: MPG - does it worsen with miles? [greenbook]
Apr 02, 2010 (10:27 am)
The HCH powertrain can be broken into two parts. Failure or inefficiency on either part can cause poor mileage. The electric motor gives the gas engine a boost when accelerating. Acceleration is what sucks the most fuel, so a boost from the electric motor helps reduce that fuel consumption. Also having the motor shut of at stops also helps unneccesary fuel consumption.
So a problem with the electrical part of the powertrain can cause poor mileage.
The gas engine is extreamly fuel effiecient on its own, but lacks power on acceleration, (thus the electrical boost). So when traveling at say 45mph, it is all gas and no electrical. To see if the problem is one or the other, I like to find a long stretch of level road, get the car up to speed, set the cruise,and reset the mpg display. If the readings are high, then there is a problem in the electrical drive system. It the reading is low, the problem is with the rest of the car: Tires,tire pressure, alignment,not using the proper weight oil, dirty fuel injector's,dirty mass air flow sensor, weak oxygen sensor, too much weight......
I just added Seafoam fuel system cleaner to my 07 GMC Envoy with a 5.3 V8 and gained 3 mpg, so I am going to try it in my civic and see if i get any results. I currently get 50mpg spring and fall 40 during the coldest months and 47 during the hottest months with A/C.
#500 of 540 Re: MPG - does it worsen with miles? [mrwaug]
Apr 02, 2010 (11:19 am)
Thanks for this advice! Does it sound to you, then, that there really is a problem, either way? I am willing to check according to the test you mentioned, but the car was recently purchased and I feel the dealer should have not sold it at such low MPG performance.
re: "Tires,tire pressure, alignment,not using the proper weight oil, dirty fuel injector's,dirty mass air flow sensor, weak oxygen sensor, too much weight...... "
- service tech people checked tire pressure and presumably everything else when I went in. We even did a drive together to make sure it was at its optimum.
If it's the powertrain, do you think its "fix"able?
#501 of 540 New Idea for more MPG
Apr 05, 2010 (8:32 am)
I have been pouring thru the HCH06-07 Honda serv. manual -I found a clue to why my HCH06 may not get max mpg..especially with AC or fan on. I suspect the AC compressor electric drive (pulls power from the 158V Bat) is not working and it pulls power that should go to ASSIST white bars .. even when engine is running. --
To see if this applies to your car ( around 39-41 MPG in most good weather conditions) then try this as a temp. test...Pull out fuse #22 near driver's foot...it is 7.5 or 10amp -- make sure it is #22 under dash fuse box.
It is a fuse that disables the drive to the electric AC compr. circuit... regular AC still works fine and doesnt steal power now from the HV Bat. My mpg jumped to 50 mpg with AC on at moderate levels ----- 20% improvement! I am still investigating......
Apr 05, 2010 (8:35 am)
I also agree with use of the cruise control for best MPGs ... the computer wants to control the car itself for optimizing power use... keep it on as much as you can.
#503 of 540 Re: New Idea for more MPG [highmpg]
Apr 05, 2010 (8:56 am)
you are absolutely correct in your findings. The A/C compressor is split into two parts, The belt drive or mechanical for when the engine is running and the 158V for when at stops. Honda and all other hybrid manufactures had to go thru great length to insure comfort when the engine stops. and they all suck power from the battery pack that then must be recharge at the cost of fuel mileage. There is even a small electric water pump that keeps hot water circulating through the heater. The electric a/c unit is not very powerful, and will deplete the battery completly on 100 deg days on my commute home, so I do something like you do, I just roll down the windows until i get through the stops, or I kick the trans in neutral and let the engine keep running.
#504 of 540 Re: More MPG [highmpg]
Apr 05, 2010 (9:14 am)
If you really want to squeese out every drop at the inconvence of loosing speed, try running as much as possible on battery only. I have an 07, and this is what i have to do. On my commute, I travel a route that has has several long streches of road that have a slight downhill grade.With a 3/4 or more battery charge, I accelerate to about 5 mph over the speed limit, then slightly decelerate untill the mpg guage hits 100mpg and the recharge meter is showing about three bars green. Then ever so lightly press on the accelerator to no more than three bars white. If all conditions are right the mpg guage will stay on 100, and you are operating on battery only. The valves on the engine are being held open so there is no compression loss. Every time that is can get this to happen, i gain .1 mpg on the fuel mileage counter. The problem is, that the car cannot maintain the speed for long,and you end up having to accelerate back up to speed.If tou go over 4 bars white while in this state, you will feel a slight bump, as the engine takes over and you will see the mpg guage drop. It can me difficult to learn, but once you get it figured out you can easly add 1 or 2 mpg per tank full. When the cruse is on, it will somtimes try to run on battery only, but will usually apply too much throttle and will fall out of it within a second or two.
#505 of 540 Re: New Idea for more MPG [mrwaug]
Apr 05, 2010 (9:19 am)
I agree with you-- less AC means more MPG...my car however seems to also send pwr to the elect. AC when the gas engine is running as well... so less bat power to assist on hills etc. This situation may be software that is glitched...or electrical inefficiency / malfunction possibility. Quite a few people report a "drop" from good mpgs to the 39-40 range ... so I suspect it is a real issue with many cars.
I drive another HCH06 that avgs. 45+ - with AC on in similar driving situations..and it gives several ASSIST bars ... whereas the Older HCH06 is often actually charging up a hill and rarely can assist...even with the fan on lowest setting and ac temp higher than comfortable. With Elect AC disabled it is same or better than 45+ car.
#506 of 540 Re: MPG - does it worsen with miles? [greenbook]
Apr 05, 2010 (9:33 am)
If it's the powertrain, do you think its "fix"able?
That all depends on the dealer.And i would say that there is a problem somewhere, but getting them to fix it depends on how hard they want to try to make you happy. I know almost anything but the original tires can kill your mileage, I am hanging on to mine as long as possible, I also keep them slightly over-inflated, which is a risk i take( remember the ford explorer's and the exploding tire issues). I gained 3mpg after an alignment. And was told that anything other than the 0/5w oil or whatever it is, can cause a drop of 7 mpg.
I dont know if you purchased from a Honda dealer, or just a used car lot, but if they have any reputation, the should try a little harder that air up the tires for you.
#507 of 540 Re: Honda Civic Hybrid MPG [frednjudik]
Apr 17, 2010 (6:41 am)
Took your advice and called Honda,they replaced the battery and upper rear control arms! Thank you.
#508 of 540 Re: hybrid gas mileage [dan11809]
Apr 17, 2010 (6:41 am)
Slowed down to 68 m.p.h. and mileage went back up to 45 m.p.g. Hope I don't get run over.