Hybrid ICE engine revving during sustained braking

[VBMav]

We were on vacation in the Smoky Mountains last week and had a very odd thing happen with our 2012 Hybrid Maverick. We were coming down the steep, winding mountain road of the Motor Nature Trail just outside of Gatlinburg. Since there is a lot of braking involved in descending the road, I thought it might be helpful to switch to ECO mode to see if the engine braking would be of help and save some wear and tear on the brakes. That seemed to be working well for a few minutes until the gas engine suddenly revved up. I have no idea the RPM it was turning but it sounded like I was merging onto a highway with lots of traffic! In other words, it was really turning. The interesting thing is that the Mav acted like it was in neutral, it didn't try to accelerate. Switching out of ECO mode seemed to solve the problem. It never did that again.

My Mav had all of the early recalls/updates done before it was delivered in October, 2022 and I have not had the last 3 recalls applied yet (23S27/23V380, 24S27/24V293, or 24C01/24V140). The only ones I have had done since delivery were involving the brakes grabbing at slow speeds, the Powertrain control module reprogram (23E09), and the Turn Signal Outage Detection System Failure (23C41). I do notice a slight surge with stopped at a light whether the gas engine is running or not.

Has anyone else had the gas engine rev up to a high RPM while braking without affecting the vehicle speed?

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[burger_time]

I had a similar experience on a long downhill grade. I was using Low gear mode on the shifter to help slow the truck down. I believe the high RPMs started when the hybrid battery was full and switched from regen to engine braking. I could see the brake pedal potentially doing the same thing, since brakes will also try to try to regen until the battery is full.

 

[Ozarkbeard]

I had a similar experience on a long downhill grade. I was using Low gear mode on the shifter to help slow the truck down. I believe the high RPMs started when the hybrid battery was full and switched from regen to engine braking. I could see the brake pedal potentially doing the same thing, since brakes will also try to try to regen until the battery is full.

This.
IIRC, It switches to engine braking (engine is off), when the battery has been charged to the max the system will allow, which is either 70% or 80% I think. The battery never charges to 100%, to protect battery lifetime.

It is normal, by design and will not damage anything. It is a bit unsettling, though, the first time you hear it.

 

[RetiredAF530]

Same thing happened to me while driving in the mountains in NorCal, I’ve owned three hybrids and all did the same…I agree it’s a very unsettling sound but great feature

 

[Sykotyk]

There are no gears. No matter what driving mode you're in there's no shifting gears.

Once the battery tops off the only thing to slow you down is the mechanical brakes or engine braking. And a small 2.5l engine is gonna be loud trying to stop a 3000lb vehicle with just the engine.

 

[Ford Motor Company]

We were on vacation in the Smoky Mountains last week and had a very odd thing happen with our 2012 Hybrid Maverick. We were coming down the steep, winding mountain road of the Motor Nature Trail just outside of Gatlinburg. Since there is a lot of braking involved in descending the road, I thought it might be helpful to switch to ECO mode to see if the engine braking would be of help and save some wear and tear on the brakes. That seemed to be working well for a few minutes until the gas engine suddenly revved up. I have no idea the RPM it was turning but it sounded like I was merging onto a highway with lots of traffic! In other words, it was really turning. The interesting thing is that the Mav acted like it was in neutral, it didn't try to accelerate. Switching out of ECO mode seemed to solve the problem. It never did that again.

My Mav had all of the early recalls/updates done before it was delivered in October, 2022 and I have not had the last 3 recalls applied yet (23S27/23V380, 24S27/24V293, or 24C01/24V140). The only ones I have had done since delivery were involving the brakes grabbing at slow speeds, the Powertrain control module reprogram (23E09), and the Turn Signal Outage Detection System Failure (23C41). I do notice a slight surge with stopped at a light whether the gas engine is running or not.

Has anyone else had the gas engine rev up to a high RPM while braking without affecting the vehicle speed?

Hello! Send us a private message with your VIN and current mileage. Allow me to see what I can do to assist. Thanks!

 

[mshapeer]

We were on vacation in the Smoky Mountains last week and had a very odd thing happen with our 2012 Hybrid Maverick. We were coming down the steep, winding mountain road of the Motor Nature Trail just outside of Gatlinburg. Since there is a lot of braking involved in descending the road, I thought it might be helpful to switch to ECO mode to see if the engine braking would be of help and save some wear and tear on the brakes. That seemed to be working well for a few minutes until the gas engine suddenly revved up. I have no idea the RPM it was turning but it sounded like I was merging onto a highway with lots of traffic! In other words, it was really turning. The interesting thing is that the Mav acted like it was in neutral, it didn't try to accelerate. Switching out of ECO mode seemed to solve the problem. It never did that again.

My Mav had all of the early recalls/updates done before it was delivered in October, 2022 and I have not had the last 3 recalls applied yet (23S27/23V380, 24S27/24V293, or 24C01/24V140). The only ones I have had done since delivery were involving the brakes grabbing at slow speeds, the Powertrain control module reprogram (23E09), and the Turn Signal Outage Detection System Failure (23C41). I do notice a slight surge with stopped at a light whether the gas engine is running or not.

Has anyone else had the gas engine rev up to a high RPM while braking without affecting the vehicle speed?

This.
IIRC, It switches to engine braking (engine is off), when the battery has been charged to the max the system will allow, which is either 70% or 80% I think. The battery never charges to 100%, to protect battery lifetime.

It is normal, by design and will not damage anything. It is a bit unsettling, though, the first time you hear it.

We were driving down a long grade yesterday in Eco mode when the same thing happened for the first time - very loud noise similar to downshifting (obviously, not possible with the CVT). It had not done this in the 3 months I've had the truck. Glad to hear it is normal - thanks

 

[tom_tucker]

"a very odd thing happen with our 2012 Hybrid Maverick"

Man, you guys are wet behind the ears with Maverick Hybrid. The battery is full, where does the energy go considering you refuse to use your foot brake down a mountain?

Don't just ride this ICE "air pump" all the way down. Do mix in some foot brake checks as well. You've got to produce brake dust in the mountains.

"Save the brakes"... and instead ride your drivetrain all the way down???

 

[The Real Maverick]

I measured this for all you folks without a tachometer.

The "high revving" is about 3200 rpm.
Totally reasonable. But loud.
Needle will be about half way into the green
It tends to really resonate here, and when you are driving you are usually not above 2500 rpm so this sounds really unusual. But it's not bad. It is by design.

If you KEEP riding the brake pedal at the same time, it will kick up to maximum engine brake. The needle will go 100% into the green, and RPM will be about 5,000.

Totally normal. And the "mode" does not matter by the way.

Hope that helps.

 

[tom_tucker]

Talk about timing - we were driving down a long grade yesterday in Eco mode when the same thing happened for the first time - very loud noise similar to downshifting (obviously, not possible with the CVT).

We were driving down a long grade yesterday in Eco mode when the same thing happened for the first time - very loud noise similar to downshifting (obviously, not possible with the CVT). It had not done this in the 3 months I've had the truck. Glad to hear it is normal - thanks

Of course, ICE engine revving is a completely normal and mandatory part of the Hybrid program.

Feather the throttle downhill (to stay higher up in the green) or turn off ECO. There is no shortage of regen energy going down a mountain so you don't need ECO. With ECO off, less throttle management required.

 

[The Real Maverick]

BTW fun FACT:

The needle in the green shows regen and/or engine braking. It's an ammeter; not a battery charging meter.

Going down a hill, needle in the green shows amps going into the HV battery until the battery reaches 70% charge.

Then, the needle stays in the green because those amps continue to flow but are shunted to the GENERATOR instead of the battery. The generator then consumes those amps to spin the engine (without fuel) basically as an air compressor. The evidence is your instant MPG will read 999.9 MPG and your temperature gauge will fall in one or two minutes because you are drawing tons of ambient temperature air into the engine, and not burning any fuel.

If going downhill and the engine is revving, the needle in the green IS your relative tachometer. If it's half way in the green, you are using 50% engine braking ability. If it's 100% (horizontal on the peg) engine braking, and probably rpm's are at their limit. If you are going too fast, time to use those brake pads.

 

[mshapeer]

BTW fun FACT:

The needle in the green shows regen and/or engine braking. It's an ammeter; not a battery charging meter.

Going down a hill, needle in the green shows amps going into the HV battery until the battery reaches 70% charge.

Then, the needle stays in the green because those amps continue to flow but are shunted to the GENERATOR instead of the battery. The generator then consumes those amps to spin the engine (without fuel) basically as an air compressor. The evidence is your instant MPG will read 999.9 MPG and your temperature gauge will fall in one or two minutes because you are drawing tons of ambient temperature air into the engine, and not burning any fuel.

If going downhill and the engine is revving, the needle in the green IS your relative tachometer. If it's half way in the green, you are using 50% engine braking ability. If it's 100% (horizontal on the peg) engine braking, and probably rpm's are at their limit. If you are going too fast, time to use those brake pads.

Appreciate the insights. My Maverick replaced a 1997 GMC Sonoma so I am getting used to (and enjoying) my hybrid. Definitely a huge change from the days when I used to tune my car with a dwell meter and timing light.

 

[PatientlyWaiting4Mine]

We were on vacation in the Smoky Mountains last week and had a very odd thing happen with our 2012 Hybrid Maverick. We were coming down the steep, winding mountain road of the Motor Nature Trail just outside of Gatlinburg. Since there is a lot of braking involved in descending the road, I thought it might be helpful to switch to ECO mode to see if the engine braking would be of help and save some wear and tear on the brakes. That seemed to be working well for a few minutes until the gas engine suddenly revved up. I have no idea the RPM it was turning but it sounded like I was merging onto a highway with lots of traffic! In other words, it was really turning. The interesting thing is that the Mav acted like it was in neutral, it didn't try to accelerate. Switching out of ECO mode seemed to solve the problem. It never did that again.

My Mav had all of the early recalls/updates done before it was delivered in October, 2022 and I have not had the last 3 recalls applied yet (23S27/23V380, 24S27/24V293, or 24C01/24V140). The only ones I have had done since delivery were involving the brakes grabbing at slow speeds, the Powertrain control module reprogram (23E09), and the Turn Signal Outage Detection System Failure (23C41). I do notice a slight surge with stopped at a light whether the gas engine is running or not.

Has anyone else had the gas engine rev up to a high RPM while braking without affecting the vehicle speed?

My 22 Hybrid "lurches" when I'm at stop lights. It feels like I have a foot on the brakes and the other revving the gas. Very odd.

 

[burger_time]

BTW fun FACT:

The needle in the green shows regen and/or engine braking. It's an ammeter; not a battery charging meter.

Going down a hill, needle in the green shows amps going into the HV battery until the battery reaches 70% charge.

Then, the needle stays in the green because those amps continue to flow but are shunted to the GENERATOR instead of the battery. The generator then consumes those amps to spin the engine (without fuel) basically as an air compressor. The evidence is your instant MPG will read 999.9 MPG and your temperature gauge will fall in one or two minutes because you are drawing tons of ambient temperature air into the engine, and not burning any fuel.

If going downhill and the engine is revving, the needle in the green IS your relative tachometer. If it's half way in the green, you are using 50% engine braking ability. If it's 100% (horizontal on the peg) engine braking, and probably rpm's are at their limit. If you are going too fast, time to use those brake pads.

The more you know

Yeah when I went down a mile or 2 of steep grade I had to pump the brake pads like crazy while the engine was revving. Probably more brake wear in those few minutes than in the prior 7 months since I bought the truck.

 

[MakinDoForNow]

I measured this for all you folks without a tachometer.

The "high revving" is about 3200 rpm.
Totally reasonable. But loud.
Needle will be about half way into the green
It tends to really resonate here, and when you are driving you are usually not above 2500 rpm so this sounds really unusual. But it's not bad. It is by design.

If you KEEP riding the brake pedal at the same time, it will kick up to maximum engine brake. The needle will go 100% into the green, and RPM will be about 5,000.

Totally normal. And the "mode" does not matter by the way.

Hope that helps.

Mode itself doesn't matter much. Down hill engine braking is the main purpose of the "L" button (see manual) an is effective no matter which mode is selected. You can per manual press the 'L" commonly called "Low" button AT ANY SPEED. Driving full time in L mode will affect mpg as it keeps ice on more if not full time so you have much much less coasting.
Drive downhill in cruise with "L" on and let control module ballance regen/engine braking/hydraulic braking..

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