A different kind of hybrid (the Accord kind)
 

After way too many hours at the dealership, my wife and I came home with a 2007 Honda Accord Hybrid with 30,000 miles. I went over my emotional responses last night. This is more of an evaluation of the Accord's hybrid system as it interacts with a V-6.

The first thing I noticed is the standard Honda IMA stuff. Engine shutoff/restart, ECO mode, regen/assist lights, etc. Except for the fact that ECO mode signifies that it is running on 3 cylinders, not lean burn. For anyone who wondered, ECO mode on/off makes about the same shudder as a gear shift (although the Accord shifts so smoothly that it is more like a normal car's shifts).

What is different? The assist is almost entirely geared towards maintaining ECO mode rather than assisting accelerating. It does seem to help acceleration before the engine is warmed up (or when you flat-out mash the throttle for a 6.7 second 0-60).

Now I wonder what I can do to keep it in ECO more easily. First I think I will see if premium fuel will advance the timing. I want to block the grill somewhat, but I'm afraid a piece of cardboard will have to do until next winter. After that?

From driving my wife's Pontiac, I would suggest very small throttle pedal movements. It has a very small vibration when running on 4 cylinders. Large throttle changes knock it out of Active Fuel Management right away. Anticipating hills (accelerating in AFM so it doesn't down shift or kick it out while going uphill) seems to keep it in AFM longer. I don't know if it's more efficient than Driving With Load or not.

Reducing air drag, rolling resistance & weight should help as less throttle movement will be required for the same change. All things I'm sure you will be doing anyway.

You could glue some poster board to the cardboard & paint it. You won't be able to see the ridges of the corrugation that way & it would blend in a little better.

Even if AFM parameters are maintained for an extended period of time the Pontiac will cycle the AFM on & off to keep the cylinders clear. I don't know if your Honda will do that or not.

Good luck
Don

You are right about nearly everything, except I have never really noticed the cycling. It might be doing it, but it often seems like it is just dropping out of 3 cylinder mode due to load. The nice part is that just paying attention to the hybrid assist/charge bars does a fair job of teaching you those techniques. The only downside is that it is basically an Accord V6 in the city; on the highway, though, 42 mpg on flat interstate.

You might try borrowing or buying a vacuum gauge. I don't know how these systems work, but if they kick off at a specific load level that corresponds to a specific point on the vacuum gauge, you can then use that gauge to try to keep it in ECO mode longer.

I really don't need much of a guage to stay in ECO; basically anything more than minimal throttle drops it out, and any real throttle change drops it out. If it needs a little more power the hybrid motor helps out to a certain extent as long as you hold the throttle steady.

I have started to wonder if Honda engineers wanted to promote a little hooliganism when they programmed the IMA map for acceleration. It takes a considerable throttle opening to get the IMA to help during acceleration. Most of the time it seems like it is there just to smooth out load so that the car can stay in 3 cylinder mode longer. However, if you really give it some throttle, the IMA will help. I wonder whether I am better off easing into acceleration with all 6 cylinders only providing propulsion, or if I am better off accelerating hard, with IMA helping, then getting to 3 cylinder operation sooner.

If it's anything like the Insight, you'll want to keep an eye on the instantaneous MPG gauge while adjusting throttle to keep it in ECO mode.

In the city, that car should deliver good economy, with its ability to shut off the engine when not needed (i.e. most of the time). You should develop a kill switch for it.

The former. Any energy you draw out of the battery has to be paid back, with interest. Rule of thumb with hybrids: to get the best fuel economy, stay off the electric assist. If you're really dedicated, then coast to a stop instead of regenerative braking. Yep, the hybrid system is best when not used.

The engine shuts off at below 10 mph if my foot is even toughing the brake, so I don't know that the kill switch is necessary. As for instantaneous mpg, you have to get the navigation to get that; ours doesn't. I'm stuck with trip mpg. City mpg is better than it should be for a 240 hp v6 because of auto stop and IMA, but virtually ANY acceleration that is not gravity-aided will throw it out of ECO. That's why I was wondering if I am better off accelerating more quickly and getting back to ECO sooner.

Sure it is. I use mine all the time, for engine-off coasting to a stop, for down-grades where the engine is not needed, and sometimes for P&G. I travel a healthy percentage of my commute in neutral with the engine off.

The more I drive the HAH the more annoyed I am with its assist programming. It doesn't help often during acceleration very often, but it will help at odd times to try to keep it in ECO mode. This car needs MIMA badly. Unfortunately, I doubt anyone will be developing a MIMA system for the Accord and that is WAY beyond my electronic skills. For now, I think I will try to make the DRIVER more economical.