Lost all Power going up mountain passes

Check your air filter. Dirty air filter will severely drop power. I had no problem at 110 km/hr (close to 70 MPH) on an 8% grade highway. Not at high altitude though. I was passing SUVs (and they were not happy ).

 

Never had a problem with my 06 on hills, Baker Grade to Vegas, 99 highway Grapevine, coastal mountain ranges. Not Colorado, but up to 4,000 + feet. I go over several long hills every day, no big deal. I set the cruise at 70, and it just zooms right up. Slowing for SUVs and 18 wheelers loses momentum, but it catches up. If this is a recent happening, get to to the dealer. If its been gradually over 2 years, maybe the battery is dying, not likely. How many miles on the car? Many Prius drivers drive too slow, and have no momentum when the hill comes up. Like I said, criuse at 70, and it should go right up.

 

Cracked spark plug wire insulation can cause a loss of power under heavy load, IFF you have a variable voltage ignition system. I am not sure if the Prius does or not. There the voltage increases when you are "bogged down" to get better ignition. This can cause marginal spark plug wires to short out to the block. Rodents sometimes chew on the insulation as well and may cause intermittent high voltage leaks. High voltage leaks get worse at higher altitude, too, because of less dielectric constant in the air mainly due to less water vapor.

I had a Saturn that wouldn't go up steep hills but ran all right on the level. I did all the filter stuff and found out about the spark plug wires by watching the engine running on a dark night while someone rev'd it. Just like lightning! A set of spark plug wires is a cheap fix.

Also, solid state ignitions can have HV leaks, too. Not a cheap fix. They s hould cause a fault code, though.

 

<div class='quotetop'>QUOTE(wileec @ Jul 31 2007, 03:56 PM) [snapback]488252[/snapback]</div>

Is this a new problem? Another poster asked this same question, but you didn't answer it. It's extremely important from a diagnostic standpoint.

Tom

 

<div class='quotetop'>QUOTE(qbee42 @ Jul 31 2007, 02:56 PM) [snapback]488285[/snapback]</div>

Wileec's wife...This problem has only occurred twice, but we have only taken it into the mountains twice.

 

Did you keep the gas pedal in the same position as when you were on a mild grade, or did you floor it?

Don't be afraid to mash the pedal to the floor whenever necessary; the engine will roar, but this is normal, and the computers will not allow it to over-rev.

 

<div class='quotetop'>QUOTE(richard schumacher @ Jul 31 2007, 03:12 PM) [snapback]488299[/snapback]</div>

I had the pedal floored, trying to get as much oomph as possible. The prius' max MPH once the battery was diminished was 50 MPH in a 75 MPH zone.

 

<div class='quotetop'>QUOTE(wileec @ Jul 31 2007, 02:03 PM) [snapback]488216[/snapback]</div>

The following chart shows what my NHW11, 03 Prius does going up hills:


The data suggests that 65-70 mph is perfectly stable and doesn't drawn much power from the battery. However, higher speeds risk drawing down the battery power and lead to 'the slows.'

Bob Wilson

 

<div class='quotetop'>QUOTE(wileec @ Jul 31 2007, 04:44 PM) [snapback]488314[/snapback]</div>

You mean "startup" the hill or "startup" in the morning?

Bob Wilson

 

This is exactly how my car behaves. Always has, even with the new battery. I live in Longmont. It actually gets better when you get closer to Eisenhower tunnel.

Nate

 

Hi Wileec,

You might check tire pressure too. Try 42 psi in the front, and 40 in the rears. That should help with rolling resistance. These are cold set pressures. Set the presures at 6 or 7 in the morning, before the sun gets on the tires, or any driving. Are you using the stock wheels and tires, or something wider ?

As an experiment, tell us how fast you can go up the hill without any arrows from the battery? This would be the steady state speed Bob Wilson mentioned. You can then compare that to other people, and before and after tire pressure changes. Bob Wilson is saying 65 to 70, but he is at sea level from all intents. What is the elevation at the start and stop of this hill?

While you have the air-filter cover off, run a wire down the intake pipe (away from the engine) to see if there is any blockage.

 

You never mentioned the outside temperature or whether you were using the AC. You have to remember that the traction battery requires a "room temperature" environment for most efficient operation. The battery does not run efficiently above 100 degrees, a pleasant cabin temp is also pleasant for the battery.

 

Hi Again,

One other thing. What was your AC set to ? The AC uses allot of electricity. Might want to run it at 80 to 83 F setting before and during the uphill runs.


Hi Seasalsa,

Looks like we doubled there.

I found that an AC setting initially at 80 , and later at 83 F on the drive home on hot days keeps the battery good. But its relatively flat here. If I drive home on my commute with the windows down, and AC off when the outdoor temp is above 82 here, by the end of the commute the car is not going to let me do any hypermilling tricks. It runs the engine allot and and there is very limited battery power available. Kinda sounds like what Wileec is experiencing. I also avoid hot-soaking the car, by keeping the windows cracked during the afternoon, and even after I get home here, till dusk. I have one of the California winshield shades too. Do not want any warped dashboard, or overheated MFD's. They really should have put some ventiltion in the MFD cover.

Waleec, maybe you should try running the AC at 75 F for 5 miles before the uphill run to get the battery cool, then 80 to 83 up the hill to keep it cool ? Lower density air has less capability to cool. So, once something is hot, it will stay hot whole lot longer.

 

<div class='quotetop'>QUOTE(donee @ Jul 31 2007, 05:42 PM) [snapback]488397[/snapback]</div>

Donee,
Not to mention the added drag from having all the windows open. It comes close to a break even for using the AC.

 

Have you considered the effect the thin Colorado air has on engine power? Any non-turbocharged engine will lose power at altitude due to the thinner air. If I remember right, you lose about 2.5-3% per 1000 feet of elevation over sea level. At 5000 feet, you are already about 10 HP down, and going up to 10,000 feet, you'll lose another 10HP, only leaving you with 50-55HP.

Also, a question for the Prius experts: once you are down to a couple of bars and run the AC, does some of the engine power go to charge the battery? If so, that would be another power drain.