Power loss & low battery during climb

Cruise control doesn't floor it until it looses quite a bit of speed/power for obvious safety reasons.

 

If this wasn't a hybrid these symptoms would point to clogging fuel injectors, carbon/coke buildup in the cylinders and intake, or problems with a sensor like the MAF Mass air flow. These would all cause knocking in the ICE under a high load like SF's short but steep hills or the Sierra hill climb. Knock sensor detects this and retards timing reducing power and saves your ICE from damage. A scangauge app set to HP and IGN might show this happen.

 

The ScanGauge idea is a good one. Other fields to check would be the HV battery current, and the HV battery Block highest and lowest voltages. If you get tired of it or sell the car, you can sell it on Ebay and get a good portion of your money back.

I don't think the question was ever answered, is the 12V battery the one that came with the car? If so, have you run the 12V battery test? http://priuschat.com/forums/newbie-forum/73400-weird-stuff-happening-mpgs-dropping-test-battery.html

 

Hi Tone88 good luck with this. Very interested to hear what the 12V test by Toyota discovers, hopefully this is the issue and you are back hill climbing at 70 with no issues. Since getting my Prius I have wondered what toll regular hill driving would exact on these cars...Happy 4th.

 

Probably a dumb question, but have you changed your engine filter yet?

 

this happens around town too?! check your ignition coils (not spark plugs)... does it run a little rough while it's doing this?

if you can get it while it's acting funny.. and pull of 1 ignition coil at a time, you'll notice the car keeps running or shuts off.. it should shut off after every pull (pull the whole thing off the spark plug, not the 12v plug.. it knows the difference) if it stays on, that coil has failed or is failing at that moment.

this car "can" run off of 3 cylinders but it lacks power.. and that directly influences soc and makes mpg drop to 20's... (it's only possible because of MG1 & 2)

if you do test this, you have to restart after every ignition coil reconnect, or else the car is in ! mode or something... errors, either way.

 

The car will code (MIL, triangle) if there is a misfire, even an occasional misfire. The misfire frequency threshold threshold is pretty low, a few % on a single cylinder. I do not think this is lack of engine power.

Tone88, even though it sounds like Toyota has pulled out all the stops and has topline experts working on your problem, it is still your car, and you know it best. Don't be afraid to do some troubleshooting on your own, particularly the 12V battery test described here. Don't rely on them to test it correctly. It is not uncommon for people to replace their 12V battery on a Prius that is only 4 years old.

 

Another thing I forgot to ask, and I don't remember anyone else asking: Do you recall having your MPG drop after having a service performed, and/or when changing out tires/wheels?

 

Hi Tone88. If you are doing a few tests yourself you could try measuring the HV battery capacity from a given starting charge (say 7 green bars). Pick some quite backstreets that are as flat as possible, then at a time of day (or night) with no traffic and just drive slowly (say 20-30 mph) on only electric power until the SOC drops from 7 to 5 bars. Pick a closed circuit if possible so that changes in elevation can be ruled out. Record the distance traveled and see if there is anything way out of line here. You should go about 1/2 a mile.

BTW. You can force charge the traction battery by holding it stationary with the brake while simultaneously applying just enough accelerator pedal to force the engine to run. Stop when it just makes 7 green bars and then drive it slowly until it drops to 5.

 

One more thing. You can test the 12V really easily without any tools. Follow the links from my post #8 here : http://priuschat.com/forums/gen-ii-...conditioning-12v-aux-battery.html#post1188923

Personally I don't think the 12V battery would cause such a noticeable problem as the amount of power it would have to be dissipating is too large. But it's an easy test so you may as well measure it.

 

Just got back from doing a trip to PHX from SLC. Has a lot of up and down mountainous terrain, and I noticed that I'd get down to 1 purple bar but not much power loss. When I went down hill and the regenerative breaking kicked in, I'd get back up into 3/4 blues and sometimes even greens, but then going back up steep grades (6%, 7%) I would get sucked dry. I also have a system (amp/sub) and upgraded DVD player in my car and was running the AC.

 

We are really interested too! Please let us know what happens.

 

This is great service by Toyota. It shows Toyota's commitment to refining and perfecting its hybrid technology much better than any ad campaign would do.

I love to see a manufacturer invest the time and effort to get to the root cause of a problem, as opposed to just letting a mechanic swap parts in order to see what happens. To me, swapping parts is a cop out that doesn't make any attempt at problem-solving. It happens far too often, though.

I understand the economics of parts-swapping. It is easier, and more cost effective, to just run the production line for a few more minutes and produce another 20 ICEs (to be swapped out) than it is to pay a mechanic to rebuild a defective ICE.

However, that "parts swap" philosophy overlooks the benefits of problem-solving and does not increase the manufacturer's knowledge base one bit. Toyota's approach to this problem demonstrates Toyota's commitment to the future of their products and their reputation.

Good for Toyota - and good for us!

 

Thanks for the update Tone88. I personally think that there's a good chance that a new battery will resolve the problem. I've been thinking that this is one of those cases where there is some degradation of the battery but not enough to cause it to fail their routine tests. Also, in other service conditions then perhaps it would even go unnoticed.

Yes it will be extremely interesting to see how this situation turns out. Please keep us updated.