No Engine Brake on COLD ENGINE

[The Real Maverick]

I noticed a weird startling effect today.

No Engine Brake on a COLD ENGINE!

2022 Hybrid

Parked at the top of an 1800' hill.
Left on a COLD ENGINE with mostly full battery. And by cold, 45-50°F.

15% 18% 22% peak downgrades. Pavement / Blacktop Residential.
Numerous hairpin turns and narrow road only 1.5 lane wide mostly. 25 mph was uncomfortably fast.

3-4 miles of continuous downslope.

Have a ScanGauge.
Left on EV after key turn.
Got from parking lot to steep downgrade in 0.1 mile.
Regen started right away.

HV Battery hit 70%+ in 0.1 mile.
Cold engine did the initial start ON GASOLINE. HV battery hit 72% and stopped taking any more regen.

Engine continues to run on gas AT IDLE (1250 RPM) to warm up engine and catalyst. 150-250 MPG indicated. Not zero. NO ENGINE BRAKE AND NO REGEN GOING STEEPLY DOWNHILL ON A COLD ENGINE.

After about 2 minutes, 1 mile or so, engine and catalyst warmed, fuel cut off (999 MPG indicated) and RPM climbed to 3500-3600 to provide engine pumping braking, as is typical.

I had to ride the brake pads pretty hard that first mile on 18% to 22% downgrade in narrow winding residential, but at least it was only 1 mile.

I probably did 1000x normal daily wear on my brake pads this day.

P.S. the L button did not help during this 2 minute warm-up period.

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[Master Blaster]

Interesting that the engine jake braking was insufficient for your situation. How did anybody allow a residential neighbourhood to actually be built with an incredibly dangerous 22% grade? The DOT design limit for a maintainable road is 7%. If the battery became fully charged and the backup jake braking was insufficient then I'd be pretty worried that you're reaching the limits of tire adhesion on that kind of angle. I daily do a mile on a 7% grade and have never even reached the point where the battery recharging limit was reached and so never had to go to jake braking.

 

[The Real Maverick]

22% grade is about 12 degree slope.
Barely enough to ski on.
But a lot for wheeled vehicles.

 

[Tim d]

I noticed a weird startling effect today.

No Engine Brake on a COLD ENGINE!

2022 Hybrid

Parked at the top of an 1800' hill.
Left on a COLD ENGINE with mostly full battery. And by cold, 45-50°F.

15% 18% 22% peak downgrades. Pavement / Blacktop Residential.
Numerous hairpin turns and narrow road only 1.5 lane wide mostly. 25 mph was uncomfortably fast.

3-4 miles of continuous downslope.

Have a ScanGauge.
Left on EV after key turn.
Got from parking lot to steep downgrade in 0.1 mile.
Regen started right away.

HV Battery hit 70%+ in 0.1 mile.
Cold engine did the initial start ON GASOLINE. HV battery hit 72% and stopped taking any more regen.

Engine continues to run on gas AT IDLE (1250 RPM) to warm up engine and catalyst. 150-250 MPG indicated. Not zero. NO ENGINE BRAKE AND NO REGEN GOING STEEPLY DOWNHILL ON A COLD ENGINE.

After about 2 minutes, 1 mile or so, engine and catalyst warmed, fuel cut off (999 MPG indicated) and RPM climbed to 3500-3600 to provide engine pumping braking, as is typical.

I had to ride the brake pads pretty hard that first mile on 18% to 22% downgrade in narrow winding residential, but at least it was only 1 mile.

I probably did 1000x normal daily wear on my brake pads this day.

P.S. the L button did not help during this 2 minute warm-up period.

This reminded me of an algebra problem....quit reading about halfway thru.

 

[Moorparkmark]

A 22% grade = a 22 foot drop in elevation per 100 feet of travel.

 

[The Real Maverick]

A 22% grade = a 22 foot drop in elevation per 100 feet of travel.

100% true.

 

[The Real Maverick]

 

[Headbanger]

I live in Pittsburgh and these streets are no joke.

 

[Cherokee]

Well I’m glad you didn’t kill yourself OP

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