Oops! I meant to say 12V battery.

 

Most auto-parts stores will load-test the battery. There's several failure modes where the battery will have a surface charge and it'll show 13v with a multi-meter, but as soon as you draw some meaningful power it drops low.

 

Thanks. It's nothing to do with 12 V battery, it did not make sense anyway. Very easy to test, stable around 12.6 volts. We can also rule out the IMA battery, as explained in previous post. I am doing other tests as outlined in previous post, and will get back when done.

 

I did my researches. The conclusion is that the vehicle is working just fine, there is no problem with the oil or oil filter, and no problem with mpg. The only problem might be with the human mind.

The key insight was how the mpg meter works. Someone posted about “averaging method”. I thought the mpg meter showed the real-time reading. That seems so much more useful to me. I had it wrong.

The car manual explains the mpg meter shows the average during a “trip”. A trip is started by pushing the button, resetting trip miles and mpg average. First reading after pushing the button is a 10 second average.

I went driving on the highway. The mpg meter was reading around 25. I pushed the button. The mpg meter shot up to 80 (apparently the maximum real-time reading)!!! Totally different.

Driving my usual route, the average mpg for the trip, after about 1 mile, was 10. I pushed the button. The mpg meter shot up to 35 real-time reading!!!

Occasionally pushing the button (only when very safe, no close traffic), it’s interesting to see how the mpg changes in different conditions, especially uphill and downhill.

The very low mpg readings I saw are explained by three factors: 1) I normally disconnect my battery, so the mpg average starts a new trip from scratch. 2) My usual route starts up a long steep hill, so the initial mpg is extremely low. 3) The mpg meter averages for the trip, and the initial very low reading from the long steep hill has a strong effect. Only after some miles does the average creep up to a reasonable average.

I did not try checking with closed loop / open loop transition with live data. It was a good suggestion to try. But the mpg is fine, so no need to check. I have not refilled yet, so do not have an overall mpg.

I really had been convinced that the low mpg readings never showed up before the oil change. I am a careful observer. But I was wrong. It must have been reading low before, I just did not notice.

So one lesson is “don’t 100% believe what someone remembers”. Memories are fallible.

Another lesson is “RTFM”. I just never would have thought the mpg meter was averaging. But in hindsight, it makes OK sense.

Thanks to the group for giving the good suggestions leading to better understanding / resolving the problem, it helped me not do anything stupid, and I hope the discussion was at least interesting to some. And I like the car so much better now that I can see what it really does. Thanks again.

 

On my 9th gen Accord I have the MPG (trip B) set to reset when I add fuel. It will always start at zero (or very low) because until the car starts moving I'm getting 0 MPG. It goes up quickly from there, and will usually be between 25-30 MPG within the first few miles (depending on the driving conditions). The instant MPG meter will move up and down drastically with every movement of the accelerator pedal. Pretty easy to tell the difference.

 

"The instant MPG meter will move up and down drastically with every movement of the accelerator pedal. Pretty easy to tell the difference." - Thanks for the additional information. Unfortunately, to my knowledge, the 2005 hybrid does not have an instant MPG meter. That's why it was confusing to me, because I did not understand it was an average.

The 2005 Hybrid has two trip meters, A and B (page 65 of manual). Each trip meter measures average mpg, not instant mpg. The two meters function identically, just measure two different trips. I don't see much purpose in keeping track of two trips, but there it is.

One switches between the two trip meters by pressing (not holding down) the select / reset button. Holding down the button for a while resets the mpg and mileage for A or B (whichever currently shown). So the only way to measure instant mpg in the 2005 hybrid is to hold down the button, and take the first reading (average over first 10 seconds). For example, the average was around 25 on the highway, then I held down the button, and it read 80 mpg for first 10 seconds!! Or the average was around 10 on local route, then I held down the button, and it read 35 mpg for first 10 seconds!!

One may also turn off the mpg reading, via a slightly complex procedure (page 66 of manual). Not sure why anyone would want to do that...

 

My 99 Accord has 2 trip meters, as does my wife's 00 Accord. Trip A we both use for total distance between fill ups, and trip B we use for between oil changes. It doesn't have a fancy mpg meter at all (instant or otherwise).

 

You could (for example) use trip-A for each time you fill the tank. Use trip-B for the entire vacation trip, say if you were driving over a multi-day trip over several tanks of gas. Or any other combination you can think of.

Some cars (not sure if yours does) can automatically reset one of them when you fill the tank - if you find the setting to switch on that feature.

 

No, none of mine self reset. We did use use trip B on our last road trip to Texas though. It also had a fresh oil change, that got logged in the log book.

 

The auto reset feature is only available with navigation in these models 03-07