In my 06 HAH, which I have had for about 3 weeks, I notice a few strange things -

1) In some driving conditions, I notice a lot of vibration in the driveline that appears to come through the steering wheel. It happens usually (but not always) during low speed cruising at very light throttle - say around 30 miles per hour, 1000-1500 rpm, eco mode, and some IMA assist. If I give it some gas, the vibration seems to go away. Since it is not always an issue, I am betting that if I take it into the dealer, they will be "unable to duplicate" my concern. Anyone have similar issues, or know of a diagnosis / solution? The NVH seems unacceptable to me for a "top of the line" car such as this one.

2) I haven't been able to figure out how to reliably get much in the way of assist from the IMA. Sometimes it "volunteers" as I read about in another post, but it's usually just as quick to go out as it is to stay on. Any tips for keeping the car in assist mode? It would seem that if you are in eco mode, it would first try to max out the assist before engaging all 6 cyls again. But this doesn't seem to be the case.

3) The third thing is that the shifting of the transmission seems unusually rough and abrupt when the car is first started on a cold day. Also seems jumpy in drive and sluggish in reverse. Ahh, maybe I better take it in to the dealer?

Thanks for any help, and sorry if you already read my similar post on edmunds.

Thanks
Alec

My guess is that the high-tech engine mounts that are supposed to help dampen vibration in the 3 cylinder mode aren't working as well as we would like them to work. (That doesn't mean that are defective). The 3 cylinder mode combined with low engine speed (caused by "aggressive upshifting to improve mpg) is a bad combination for vibration. I don't really feel that much through the steering wheel, but it's more like "whole car" or the feeling the engine/drivetrain is vibrating, like lugging down a 4 cylinder manual trans. car.

The low-speed eco-mode only vibes are almost certainly from running an odd # of cylinders. Damping systems, like anything else, have preferred bands in which they work best- low speed, low rpm is not one of them for this setup apparently. If you consider most of your driving, it is probably not cruising down in the 20mph range anyway. This vehicle is very clearly optimized for highway work.

Rough cold shifts...sounds like a run of the mill tranny issue. Is the fluid at the proper level? Maybe have it flushed.

Assist... The best advice is to not worry about IMA at all. Let it do its thing and simply drive smoothly, cinsistently, and gently. The amount of assist is a function of battery state, throttle setting, and engine load. With 6 bars of battery you will get assist at the drop of a hat; at 2 bars almost never, and you'll get 'forced regen.'

The very short on-off you see is probably the ECU thinking initially that assist would be helpful, then deciding against it because either the incline changed or the throttle got stomped a little further.

IMA is only engaged (in eco mode) when the ECU determines that IMA alone can handle the additional load. If the combination of grade, throttle, engine load, and gear/speed/torque requirement computes to more than what IMA can provide, it instead flops over to the other 3 cylinders. The relative merits or disadvantages of this are many the bottom line is the Honda engineers decided one way or the other and that's what we've got.

Having said that, it is possible to accelerate with IMA lit up- practice on smooth roads and you will be able to hold onto 1/2-2/3 of the bars lit up for significant periods. Also notice the s...l...o...w acceleration this way. Generally I don't even try, and simply accelerate gently enough so that gearshifts occur <2K rpm. This is coincidentally good enough to keep decent fuel economy yet not clog traffic.

Take the weekends and explore what that car can do on a nice stretch of clear road- learn how steady your foot should be on the pedal to hold IMA assist, learn how to get to 42mph, see the sift into 5th, then drop and cruise at 38-40 in 5th, etc (I have found 40mph to be a gass-guzzling speed if in 4th- always try to be in 5th!) . And don't forget to enjoy the fact that it can and does outperform so many other cars out there, yet kills them on gas!

My car is vibrating so bad at 50-53 miles per hour and 1500 rpm's that I cannot drive it for any distance without my hands turning numb. Yes, the dealership can easily duplicate it (and at different speeds too). Diagnostic codes have come up with a 'bad' motor mount. Both the front and rear have been replaced, but nothing has been resolved. The Honda district service manager agrees there is a problem and now 'THE' techician is being 'flown in' to look at it. I understand to increase the gas mileage, changes needed to be made, but it seems like they haven't been perfected yet.

sorry to hear about your problem. The good news is Honda acknowledges it- you're miles ahead of many. You are the 1st I've heard of having the problem at high speed.

All I can say to 'comfort' you is that any system, no matter how simple or complex, can have problems at any point. Unfortunately the gremlin decided to take up residence in your engine mounts (or rather, somewhere else, apparently). Complexity makes it easier to foul up, but anything can get fouled.

I hope the next-level technician can figure it out for you.

This problem was sort of resolved in my car.

My dealer was able to get a code for the engine mount (front, in this case) and they replaced it. The problem went away for a while, but it seems to be creeping back. They said that replacing the ECU was the next step.

well, that's progress. Complex problems require slow, steady troubleshooting and incremental solutions. Only changing one thing at a time.