Prius Slow Acceleration

yes, it's more common than you might think. how are your mpg's? that's a big clue.
feel the wheels after you've been driving awhile to see if one is warmer than the others.
put it in neutral and see how it glides.
lastly, jack it up and spin each wheel to make sure there's no drag.

 

+1 to what bisco said ^^^.

The design of the HSD/PSD is such that it is quite normal for the engine to go to quite high (sounding) revs in the situation you quoted. In this respect, it is quite different from any other car you may have driven. Having said that, do not be afraid to let the engine management computer do what it needs to do in response to the commands you give it.

The acceleration should not be slow, although that is relative to what you are used to. It definitely will not be the same league as a 6 liter (350 cu in) V8! It should, however, be comparable to a 2.0 -2.2 liter sized car. It think the spec is ~10.5 sec 0-60?? I came from a 3.0 liter Camry and didn't find it to be too awful, but noticed it most in the speeding up to overtake department, it was definitely slower.

If it is definitely slower that the spec'd ~10.5 sec, then it may be showing signs of an aged HV battery on the decline.

Hope that helps.

 

It really depends both the condition (health) and the state of charge of the traction battery. Next time, take a look at how many "bars" of charge are showing on the battery (in the energy monitor display) when this is happening. Also see if this "state of charge" is remaining steady or if it's dropping as you accelerate.

If the engine is cold then the state of charge may drop relatively quickly, before you can get up to speed, and then the engine has to work very much harder.

The feeling of a lack of power is very much relative, but if it feels very sluggish then keep a watch on what the battery level is doing. To be honest, this is just as likely to be due to a worn tired traction battery as it is anything else. So watch your state of charge. Are you maintaining a good 6 blue bars most of the time?

 

sounds about right. it would be like getting back in the pontiac and saying, 'trans am low mpg's'.

that being said, your driving a 9 year old car with how many miles? maybe you should test drive a new one to see the difference.

 

Ok that all seems fairly normal. That falling to 1-2 purple bars when you start thing, while not uncommon, is probably an indication that the HV battery is getting a bit worn. Mine does the same (if I don't let the engine warm for about 45 seconds).

The reason why the HV charge often falls like that is because until the catalytic converters warm up (usually the first minute or two), the Prius tries to use electric propulsion as much as possible and minimize the engine loading. This hammers the HV battery pretty hard, so when they get a bit old and tired they drop too much charge and you end up with only one or two purple bars like you're seeing. This also makes the engine work REALLY hard, as you've discovered.

The solution is surprisingly simple. You just let the engine idle (I leave it in P as it also pre-charges the battery a little bit) for about 40 to 60 seconds before you drive. It wastes little to no gasoline to do this, and it makes a huge difference to the battery (no more dropping to purple bars). So give it a try. Also try not to hammer it for the first minute or two.

The thing about the Prius is that the engine IS underpowered for the weight of the car. The electric motors are needed to make up for this lack of power, but they need the HV battery at a decent state of charge before this is possible. The lower the bars of charge get then the less electric assist it will give you. And by the time you're down to purple it's all gone (and may actually give a "negative" electric assist as the electric motor/generators rob engine power in a desperate attempt to recharge the battery.)

 

there's a thread here by 's keith' on grid charging results, which maybe helpful to you.

 

Yes, from what I've seen they can improve the battery health somewhat by helping balance the cells. I don't think it's anything like a magic bullet that will restore your battery to new condition though.

In the short term I'd try just getting the most out of what you've got until you've had a bit longer to assess it's current state of health. Try the simple trick I mention above for a few days and see how much better it feels when you stop letting it "drop to purple" every time you start. It's a very simple trick and I can assure you that it works.

BTW. You may need to adjust the warm up time depending on how hard you need to accelerate in the first minute or two. If you've got a few back roads and can take it easy for the first 1 to 2 minutes then you don't need to warm up for long. If however you need to hammer it fairly hard straight away, then warm it for longer. Just experiment and see, I only need about 40 seconds because I can start out slow, but if you need to go harder (hills or accelerate onto a main road for example) then you just need to warm a little longer. You'll know when you've got it right when there is no loss of charge in the first couple of minutes.

 

These cars are about 9.5-10 seconds or so 0-60. Poor power and the engine revving unusually high is often an open in the battery circuit (including high resistance in any battery cell).

XT1585 ?

 

I read this thread with interest and thanks for the good information. I have a 2004 Prius with 258,000 miles and the original traction battery. I think the battery has some decent life left in it but it definitely is not like it was when new. I usually hit green during my daily driving and the battery usually stays at the top blue bar. If I am in stop and go it will go down to about half. If I'm in a traffic jam with AC blasting (South Florida) it can get down to 2 purple bars. Once I'm underway again it only takes a few miles to get back to top blue. However, the mileage is not as good as I used to get. I drive on the highway at 75-80 and suburban driving at around 45-50 and over the course of a tank I'll be lucky to average 41 mpg. I guess that's still good but definitely not like it was when new. I guess I should count my blessings. The car has been pretty bullet proof and I never expected to get this many miles from it!!

 

I also had a similar question. I hear the engine working hard when I press the accelerator fast. Is this normal? Does it in any way hurt the engine?
Would it help to clean the catalytic converter or the throttle plate?

 

nature of the beast, it is very low hp, plus, you're working with the ecvt

 

I worry that Prius is slow in acceleration. But I drive very carefully which leads to 56 mpg. Could Prius be faster with the same mpg? I tried to drive fast but then mpg dropped to about 43. So, I’m puzzled.

 

it's called physics

 

It is very unlikely.

I'm not sure why you're puzzled. It is common with any gasolene car that when you go faster you get lower MPG. Prius is no different.

 

In controlled conditions like a closed test track, probably.

In traffic? Probably not. You're doing great.

 

It sure can...... downhill lol!