Hi,

I've just scanned through the forum and haven't noticed anyone else with a similar problem: the electric assist frequently will not kick in when I need it to, like when I'm merging into traffic on the interstate and need to accelerate fairly quickly. I'm wondering if this is normal operation, or if it sounds like there might be something wrong.

Most of the time, it operates like I think it's supposed to - when I press down on the pedal to accelerate, the electric assist will kick in and help, with the bars on the charge meter rising in proportion to how much I've pushed down the pedal. Around 30-40 % of the time though, I'll press down on the pedal to accelerate, and the IMA won't kick in at all, leaving the poor little gas engine to do all the work itself. As you can imagine, trying to accelerate rapidly (especially if it's from a complete stop) with only the gas engine and no electric assist doesn't work very well. The car barely accelerates at all and kind of wheezes pathetically, and I nearly get run over trying to merge into traffic already on the highway. I also succeed in pissing off everyone who had the misfortune of being behind me.

I never know when the IMA is going to decide not to help, so it's made me a bit paranoid about pulling out in front in anyone (even with lots of room to speed up). It seems to occur more frequently when it's really hot outside - I live in Houston, and we've been averaging in the 100's lately. I've read that the battery doesn't perform as well in extreme heat, so I've figured that might be the cause.

I've had the car for about 4 months now, and i've been mostly happy with it aside from this issue. So is it normal for the IMA assist to not kick in sometimes, or does this sound like a problem? Any thoughts would be greatly appreciated.

 

I've never encountered an issue such as this... NEVER. I wonder if your vehicle is operating correctly...

You did mention the heat, which could be a possible cause. I also wonder about your SOC (state of charge) - if it's down to 1 or 2 bars, perhaps that could be the cause?

I'm sure others will chime in with possible ideas also. I wonder if anyone else has experienced this...

 

It doesn't seem to be related to the amount of charge...it'll do it even when I still have plenty of bars of charge left.

 

I would get that checked out. I've noticed that the car will use less assist when my battery is low (3 bars or less), only using assist if I REALLY need it, until I charge up some. That said, if I stomp the pedal while it's got a low charge, it ramps up the assist all the way. Also, I've never had it not assist from a dead start, at least at the very beginning. (When the SOC is low, I will occasionally get a blip of assist, then it'll turn it all over to the ICE if I'm accelerating slowly...saving the remaining charge for emergency use).

 

Ben,

I too have just recently noticed this, although its been "hot" for a while here in the Austin, TX area. Last week I think was the first time I noticed, where I got only 2 bars of assist, and the engine ended up reving to 4k (or more?). The battery level showed about 3/4 charged. Its happened maybe a few times since then, but completly hard to tell when it will only give me a couple of bars, or all the bars. Typically I get 4-6 bars of assist.

Been having a number of "heat" realated issues, as I have noted in previous posts, including the battery not charging back up, auto-stop not working when hot. I made the mistake of taking my car into the dealer to have the odometer fixed (part of the service call for cars made before 2006) and they couldn't reset the odometer, so now I not only drive around with no idea of mileage, but look at a line of dashes for all readings. At least the MPH work!

I am thinking that these cars (2006 model at least) were not made to handle the heat in Texas.

Regards,

Bob

 

If you are not using the AC, I could see this happening while the IMA batteries are TOO hot. I live in DFW area of Texas, and have not noticed this. I USE my AC, btw! (AUTO, set to 76-80.)
I'll be on the lookout for it, though. I can't imagine I've missed this though, if it happens as frequently as you are experiencing it.

 

Correct.

The IMA Power Control Module will (by design) prevent any assist if any of its modules MCM, BCM, DC-DC converter, or AC driver overheat. Keep the passenger cabin cool and it should help.

Cheers;


MSantos

 

If you can repeat the problem, bring it to the dealer and show them.

 

That does sound like some sort of defect, possibly heat-related, but I will add my own observation that the amount of charge on the battery makes a difference. It won't regen if the battery is fully charged and it won't assist if the battery is low. One reason is apparently because AS doesn't function unless the battery has a lot of charge. So if you're really riding that accelerator and you've dropped the battery meter faster than it can recharge while you are driving, then maybe that's the problem. Without knowing how you drive, though, I still suspect a defect.

 

Thanks for the thoughts. My car is parked out in the direct sun all day every day while I'm at work, so I would imagine it heats everything up pretty nicely. It seems to do it most often right after I leave work...in particular, there's a stop sign right before I get on the feeder road. There's always heavy traffic on the feeder, so I pretty much have no choice but to pull out and stomp the pedal or get hit. The IMA won't kick in half the time, so I'm left puttering along while pissing off everyone behind me who has to slam on their brakes.

It does seem to be heat related...it's been hot since I got the car 4 months ago, so I don't know what it'll be like when the weather cools off. It doesn't seem to do it in the mornings either, after my car has been in the garage all night.

I'll keep an eye on it and see if I can pin down when it seems to do it most...