Hybrid "bucks" at 47mph

[rpreuss]

I saw oldschool1962 mentioned this in two other threads. Though I would start a new one with what he reported.....

 

 

Has anyone experienced a stumble or lope in the vehicle when it is moving at 45-47mph? It's kinda like the car can't decide whether to use EV or the ICE. it is very noticeable and abrupt and is something that you can't miss. It happened when I was driving in an area where the speed limit was 45 and the road is relatively flat for about 2 miles. Wasn't trying to keep it in ev mode just driving the car but the pressure on the pedal was at a point where the car started to buck......yeah....that's the description I was grasping for.....buck!

 

 

Yes. I have noticed this several times. I concluded it was a minor "bug" in the software design of the hybrid control computer software.

 

Remember the "rule" the ICE must be running above 47mph. This is to keep the MG's from spinning too fast.

 

Now, if I am uncounsiously driving at EXACTLY 47 in a situation where below that speed the car wants to be in EV mode, the engine will start and stop rather quickly if I am sitting right at the threshold and slightly varying the speed.

 

I figured out that after a while, enough people would observe this that they might add a little hysteresis to the algorithm at that point. Maybe not be in too much of a rush to shut off the ICE as the speed drops just below 47. I was just going to wait for rev 1.02 of the software and in the meantime, increase or decrease my speed away from 47 to stop the "buck". But maybe that's "passing the buck" :hysterical2:

 

So, has anyone else observed this issue and have any ideas about it?

[Grey]

47 MPH is the threshold for ICE, Wehn I drove 110 miles at 45 MPH, the ICE only came on going up hills or to charge the battery.

 

Solution - drive 45 or 50 ---not 47.

[rpreuss]

47 MPH is the threshold for ICE, Wehn I drove 110 miles at 45 MPH, the ICE only came on going up hills or to charge the battery.

 

Solution - drive 45 or 50 ---not 47.

 

Unless the traffic is moving at 47.

[Oman]

I have noticed that if I am at 47MPH and have a very light touch on the accelerator, when the ICE kicks in there is a slight increase in power. This causes the slightest lift on the accelerator which drops me back to EV, and then I'm back on the accelerator. They have the software set to be very aggressive in going to EV mode. They need to add a dampener that EV won't re-engage before a second or two after it moves to ICE.

 

Jon

 

 

I saw oldschool1962 mentioned this in two other threads. Though I would start a new one with what he reported.....

 

 

 

Yes. I have noticed this several times. I concluded it was a minor "bug" in the software design of the hybrid control computer software.

 

Remember the "rule" the ICE must be running above 47mph. This is to keep the MG's from spinning too fast.

 

Now, if I am uncounsiously driving at EXACTLY 47 in a situation where below that speed the car wants to be in EV mode, the engine will start and stop rather quickly if I am sitting right at the threshold and slightly varying the speed.

 

I figured out that after a while, enough people would observe this that they might add a little hysteresis to the algorithm at that point. Maybe not be in too much of a rush to shut off the ICE as the speed drops just below 47. I was just going to wait for rev 1.02 of the software and in the meantime, increase or decrease my speed away from 47 to stop the "buck". But maybe that's "passing the buck" :hysterical2:

 

So, has anyone else observed this issue and have any ideas about it?

[rpreuss]

I have noticed that if I am at 47MPH and have a very light touch on the accelerator, when the ICE kicks in there is a slight increase in power. This causes the slightest lift on the accelerator which drops me back to EV, and then I'm back on the accelerator. They have the software set to be very aggressive in going to EV mode. They need to add a dampener that EV won't re-engage before a second or two after it moves to ICE.

 

Jon

 

That's it!! It does come "naturally" and not "consciously". It's that little power surge. I quickly either back off or go past the bucking point, but I am surprised no one else has reported. it.

 

That dampener is a good idea for another reason. There are times, especially in rush hour New Jersey stop and go traffic, where I accelerate a second, then back off to slow down. ICE is on and off and on and off. There needs to be that one or two second delay.

[oldschool1962]

I brought it up today and the Service Manager stated that if my car had a torque converter he would have the answer. He explained that was the threshold that the computer wanted to lock (or not) the converter. He didn't have an answer for the hybrid because it doesn't have a torque converter.

 

What ya'll are saying makes sense but we drove the car 3 times today for issues the Engineers wanted him to recreate. He drove the car and hovered around the 45-47mph and the car didn't act as it did yesterday. On the third drive we even took it the same route that I did yesterday when it happened. Nothing......just as it has been 3 times a week since I bought the car back in October.

 

Like I said.....what ya'll have mentioned makes perfect sense but why would it just start now after months of driving and why would there be the thud I mentioned at the same time (but not simultaneously)?

 

Maybe it's one of those things I have to see if it gets worse or becomes more frequent?

[lolder]

I have noticed that if I am at 47MPH and have a very light touch on the accelerator, when the ICE kicks in there is a slight increase in power. This causes the slightest lift on the accelerator which drops me back to EV, and then I'm back on the accelerator. They have the software set to be very aggressive in going to EV mode. They need to add a dampener that EV won't re-engage before a second or two after it moves to ICE.

 

Jon

 

This is probably how they got it to have better mileage than the Camry which is about the same size, weight and horsepower. They have made EV mode more aggressive. Look at this as if it were a shift point in an automatic transmission.

[probowler]

Unless the traffic is moving at 47.

There is no speed limit anywhere in the country set at "47". If the limit is 45, anybody going 47 is speeding, unless you happen to be on some major road where the limit is 50 or 55.

 

Solution - drive 45 or 50 ---not 47.

Edited March 11, 2010 by probowler

[oldschool1962]

Right now the municipalities in the area are "Ticket Happy"........with all the cuts in things so they're trying to generate revenue any way they can. With what I've seen regarding the "presence" in the area......... 45 "IS" 45 and 35 "IS" 35 or any other posted speed limit. So it looks like at least for us here in South Central Virginia it's gonna be a bucking contest to see who's bucks the worst or maybe "the Buck stops here"?

 

I do have to wonder if the indecision of the computer, aggressiveness of the EV mode, the ICE or what ever the case may be..........is it enough to cause damage to the eCVT or even the CV joints? Even a hard shift could play he11 with those components if they weren't made to experience it. It may come about there will need to be a patch for the drive system to have the delay Jon and rpreuss mentioned. I would certainly welcome it.

Edited March 12, 2010 by oldschool1962

[rfruth]

I'v not noticed this at all :)

[Juris]

I'v not noticed this at all :)

 

Nor have i, after 10,000 miles driving since June.