Throttle oscillation + CVT acts like it is in neutral or is fighting the brakes

The car is basicly worthless without a healthy hybrid battery.

The engine is screaming because there is no contribution of power from the hybrid battery and power is solely provided by the 11 years old 90 hp motor which probably has 200000 miles on it so let’s say it’s more like 50 horsepower motor. And your driving it with the same expectation of acceleration as a car with a healthy battery. The motor will be screaming.

Be aware there have been reports of battery fires with continued driving with a failed hybrid battery.

 

welcome!

is the air filter clean, and the connections tight?

 

The premise that you can operate the Prius without a functioning traction battery is flawed. The Prius engine operates on the Atkinson cycle (vs. Otto cycle) which means it has very low torque output at low engine speed.

As Ed pointed out, continual operation of the Prius with a failed traction battery may result in a fire as the failed module(s) overheat since all of the electrical energy provided to those modules is converted to heat.

 

amazing the engine starts at all. or maybe it isn't.

 

I don't really think it is a "head scratcher".

The car is just not designed to work without a functional HV battery.

Your car is in limp mode, which is really only to get you to the side of the road safely. It is not an alternative propulsion mode.

 

I don't really think it is a "head scratcher".
The car is just not designed to work without a functional HV battery.

x2
Step 1: Before you chase your tail and dump a bunch of money fighting a ghost, fix the obvious
Step 2: Sit back in amazement as your car returns to normal operation...............

Jaron,

There is a formidable amount of knowledge and experience in this forum. Make use of it brother. Welcome to the forum.

 

Jaron,

The more you drive the car with the battery in t's current condition, the more damage you risk to the battery. Typically, from what I have experienced, is that the battery is continually charged by the car due to the low module voltage. Excess charge=excess heat generated. Once the other 27 modules are at capacity, all that current that is still being thrown into the battery is turned into heat. At the rate you're going, with 144f, you're going to end up needing to just replace the entire pack.

 

I agree with both these statements. The ability to revert to being a regular ICE vehicle seems to be an occasionally embraced false mythology.
Toyota calls the system "Synergy" drive. And it's called a Hybrid. You would think that would be clue enough to illuminate that Prius isn't designed to work with a failing Hybrid Battery. But for some reason there does seem to be a population of people that like to believe the machine is capable of simply magically becoming a pure ICE vehicle if the battery fails, or sometimes the opposite, a pure electric vehicle if the engine fails. Neither is true.

To the OP, it is possible you have multiple issues happening. BUT...as long as you KNOW the Hybrid Battery is failing, trying to put out the other fires, without resolution of the Hybrid Battery failure, makes diagnosis near impossible and repair nearly futile.
The FIRST diagnosis is your Prius isn't operating correctly because the Hybrid Battery is failing.

 

Park the car till you fix the traction battery before you have a fire, cause a wreck, or both.

 

I agree.

 

I suspect poorly performing battery modules were causing the system to cut out.

Extreme heat is a factor in battery longevity, and may be a by product of poorly performing modules, but ultimately, it is poor battery performance that is the problem. Utilise window tint and a windshield screen to reduce internal temperatures.

If the HV battery had been subject to dormant heating, the cooling fan would come on at an appropriate setting to cool it. As the car's internal environment is used to cool the HV battery, the cooler the interior the better the cooling of the battery.

Nobody has reported such an experiment here to my knowledge.

I don't think your supposition about heat is correct – while a factor it is not the only consideration. A battery getting hot is more a sign that something is wrong. in addition, there are many more inputs to Limp mode than just the battery temp – things like the ability of the battery to store and deliver energy; the overall capacity of the battery. A lot of the exact parameters are locked up in proprietary Toyota docs and are not available in the public domain. That is why you are not getting any concrete replies to your questions. Feel free to conduct your own experiments and, if you care to, report back to add to the collective knowledge.