Poor Fuel Economy After Brake Change

who did the brake job?

how are you measuring mpg? manual calc at fill up is the only reliable way

put her in neutral, and see if she glides okay

if they disconnected the 12v, it just needs to relern everything

 

Have you reviewed any of @Mendel Leisk's posts on the rear caliper piston orientation?

 

eerily topical post from earlier today:

Fuel consumption increase after service and new brakes. | Page 2 | PriusChat

 

i can't see any reason why not. of course, when you put it in drive, you get regen braking

 

if the rear wheels spin freely, i don't see how the brakes could have been installed incorrectly

 

when you let off the brakes, the bar should go to regen, even uphill, and the car should slow down. that's not an issue.

 

42 mpg driving at 90 mph? Impressive!

 

no adjustments or settings that i can remember from my gen2 days. i wonder if coincidentally, the hybrid battery took a turn for the worse at the same time the brake work was being done

 

Check your tire pressure. This could be the cause of you not being able to roll as easy.

Higher tire pressure = less rolling resistance.

Posted via the PriusChat mobile app.

 

I don't understand then.

It's completely normal for low grade regenerative braking to occur when you let off the gas pedal.

This is partially to deliver a charge to the HV Battery, and partially to simulate how compression of the engine slows a vehicle in a standard ICE/automatic transmission vehicle.

When you shift in to neutral regenerative braking ceases.... that's exactly what's supposed to happen.

I own a Gen 2 so I can't speak to the exacts of your Gen 3. But did it not go into regenerative braking everytime you let off the gas before the brake job on the energy monitor? Because it should have been.

Here is a definition I wrote of braking in the Prius:

There are two braking modes in the Prius.

Friction brakes through the brake pads/rotors using direct input from the brake pedal through hydraulic lines, assisted by an electruc brake pressure accumulator to help with braking power. This accumulator will make a buzzing noise frequently when pushing the brake pedal.

And regenerative braking... which uses electric current from the Hybrid Battery and magnetism to slow the vehicle. During regenerative braking, electric current from the Hybrid Battery is applied to a hollow coil of wire, inside of which Motor Generator 2 (MG2) is housed. MG2 is a rotating assembly that contains lots of magnets and is directly connected to the wheels through the transmission. When MG2 rotates, the wheels rotate. When current is applied in a certain way to the coil of wire while the wheels are spinning, it slows the vehicle through electromagnetism by acting upon MG2's magnets. This has a secondary affect of simultaneously generating an electric current to recharge the Hybrid Battery. That's why it's called regenerative braking. The Prius also scales this affect. The harder you push on the brake pedal, the more it increase the regenerative braking affect. this slows the vehicle quicker and regenerates more energy for the Hybrid Battery. This effect continues until you reach a speed of under 7 mph, the battery fully recharges, or you brake really hard. then the hydraulic brakes take over.

It's also the same principle in reverse that drives the vehicle forward in electric mode. Current is applied to the coil in a way to spin MG2 forward and in turn drive the wheels forward.

You will hear a high pitched electric whirring noise when the vehicle is braking in this mode and when current is being applied to drive the vehicle forward in EV mode.



Posted via the PriusChat mobile app.

 

perhaps the gas pedal interface is worn, and not sending the proper signal to the motor generator when you apply acceleration