Starting Engine from a Stop

[scott011422]

Had a buddy ridding with me last night. He noticed the lurch from a stop where the ICE takes over. Asked me why I wasn't starting the engine prior to moving. I asked him what exactly he ment. Apparently you can start the ICE of most Hybrids by tapping on the gas. I tried it and yep, ICE starts right up.

I'm not sure this is common knowledge or not, So I figured a post couldn't hurt.

So:

1) Take foot off brake.
2) Give the gas pedal a quick tap, seems about 1/3rd of the travel (Engine should start)
3) Drive away under ICE.

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[Gros Ventre]

I observed on an Escape Hybrid that if you're at a stop and you're going to go to high power from engine off, you needed to start the engine while stopped. On the Escape Hybrid you can do this with the Heater Selector Switch by putting it on Defrost. The issue is you can spin a bearing damaging the engine because there is no oil pressure and you jump to a high power setting. Thus when the bearings get a high load, particularly those bearings at the far end of the crankshaft from the feed, they have not fully setup the oil cushion needed to protect bearings.

 

[Ziggy73]

True, but if you're going to do this you could probably just have purchased a regular 3.5, the reason for the hybrid is to get the weight of the vehicle up to speed for fuel economy. You are always getting electric boost whether the engine is on or off. I do agree, there is a lack of smoothness sometimes, but not all the time.

 

[scott011422]

You made a point, then argued against your point.

I’m not saying for or against it, I’m just posting something people may not know.

Unless you are accelerating at a walking pace, accelerating from a stop sign with 45+ mph limits, EV mode lasts a few feet at most from a dig.

 

[Gros Ventre]

The issue is the first few revolutions of the crankshaft. If you punch it from engine off, you risk spinning a bearing by putting a high load on the bearing before oil gets to it.

 

[Gros Ventre]

I installed a 24VDC oil pump in the lube oil system of my Escape Hybrid. I used a pressure switch to turn it off when the engine was up & running with normal pressure. My goal was just to keep maybe 5 psi on the bearings and thus the oil was there when needed. My experience with bearings in equipment on Navy ships led me to do this... Overkill? Maybe, but that engine is now at 450,000 miles...

 

[scott011422]

Not really, wouldn’t you have that issue every time and engine starts?

and as far as EV mode switchover goes, the bearings are still oil soaked from just running. Also I believe there is a pump keeping oil under some amount of pressure. Not 100% on that, I saw that “somewhere”. Could be false.

 

[Gros Ventre]

Not really, wouldn’t you have that issue every time and engine starts?

and as far as EV mode switchover goes, the bearings are still oil soaked from just running. Also I believe there is a pump keeping oil under some amount of pressure. Not 100% on that, I saw that “somewhere”. Could be false.

Not on a normal start where the engine only comes up to idle rpm. For oil soaked bearings, the issue again is going to a high power level suddenly. If you just routinely accelerate the bearings will be fine. I'm only addressing the case where you "punch it" from all stop. As best I can determine from the shop manual (a CD) there is not an electric oil pump for the engine. There is an electric oil pump in the Transmission.

 

[Samson16]

Try this and see what your friend thinks:
1. Choose Sport mode
2. Press traction control off
3. Press it again and hold until stability system is disabled
4. Press 4H
5. Press e-lock on
6. Left foot on brake
7. Right foot press gas pedal and hold until boost shoots up
8. Stomp gas pedal while releasing the brake pedal
9. Smile

 

[Snakebitten]

Not really, wouldn’t you have that issue every time and engine starts?

and as far as EV mode switchover goes, the bearings are still oil soaked from just running. Also I believe there is a pump keeping oil under some amount of pressure. Not 100% on that, I saw that “somewhere”. Could be false.

It's true that both the HPTuners PID and the Forscan PID report oil pressure as ~14-15psi when the Powerboost shuts ICE down. You will notice that even the instrument cluster will show oil pressure on a "shelf" just above zero, implying the same.
Both are absolutely intentional values because on the 3.5 Ecoboost Ford does NOT show a value above 0psi during auto/stop-start.
I have no clue how Ford could hold oil pressure with ICE off on the Powerboost. And certainly not as steady as it indicates. With ICE running, oil pressure is fluctuating several psi per second. If your OBD refresh rate is fast enough (HPTuners is), the value is changing several times per second.
But it's almost completely static when the Powerboost is in EV mode.

I'd love to find any kind of documentation regarding. I've looked quite a bit. But have found nothing even mentioning oil pressure in EV mode.

 

[fordtruckman2003]

Subtract atmosphere from the oil pressure PID value. Might still be above zero.

The auto start/stop equiped ICE trucks have extra lines to keep oil where it needs to be for constant restarts. I thought the PB has something similar in design so oil would never be a concern even stomping on it?

 

[Snakebitten]

Subtract atmosphere from the oil pressure PID value. Might still be above zero.

The auto start/stop equiped ICE trucks have extra lines to keep oil where it needs to be for constant restarts. I thought the PB has something similar in design so oil would never be a concern even stomping on it?

On the non Powerboost Ecoboost, oil pressure drops to zero, as expected, when the ICE stops. So I don't think the PID at 14 Psi on the Powerboost is a 1 atmosphere scale.
And you would think that the Oil Pressure gauge on the digital cluster would be identical on both trucks, but again, the same Ecoboost motor in the Powerboost holds oil pressure with the truck in EV mode.
Ford wants us to believe oil pressure is not 0psi on the Powerboost.

I personally believe it's zero regardless. Especially after a few seconds. I respect that there's anti-drainback in play and that the motor isn't quickly drying up. But I don't see how without some obvious apparatus that oil pressure can be held in place.
If that graphic image and PID value for the Powerboost are nothing more than fake, it's really amazing that the conversation to do so took place with a straight face amongst engineers.

 

[Big Dog Daddy]

The auto start/stop equiped ICE trucks have extra lines to keep oil where it needs to be for constant restarts.

I'm not sure what you are trying to say here. The 5.0 Coyote's oil pump is directly driven by the crankshaft, when the crankshaft stops turning during an auto start stop event the oil pressure drops to 0 until the restart commences. What extra lines would maintain oil pressure during a start stop event in an ICE engine?

 

[Boyk1182]

So testing the 0-60 time at a stoplight might not be the best idea on the PowerBoost is what I’m taking from this.

 

[Snakebitten]

So testing the 0-60 time at a stoplight might not be the best idea on the PowerBoost is what I’m taking from this.

I really don't see how it's any different than a 0-60 blast from a stoplight for any of the motors with auto stop/start.

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