First Tow - Does Powerboost Utilize “Electric Boost”?

[Jerome10]

First time towing yesterday. Cargo trailer several hours on the expressway. Some hills and such with a few longer grades.

I did more manual shifting rather than let the truck choose. I recall reading that using more revs to keep the engine out of boost helps with fuel economy and engine temperatures. I don’t mind 4000rpm. Seemed to work fine.

But one thing I did notice and wanted to ask, is sometimes I would be on a grade, 8th gear, and at the start of the grade no boost would be used. Then after a bit of time suddenly the boost would spool up. The grade to my eye seemed pretty steady (didn’t suddenly get steeper).

I noticed this repeatedly where a gear I thought was out of boost after some time would end up with boost.

So I’m curious, does the Powerboost use the battery first as “electric boost” and then once the battery is depleted it then spools up the turbos? It’s the only explanation I can think of as to why no boost then suddenly boost on a grade. Unless there were slight changes in incline or wind resistance. But this pattern seemed to be pretty repeatable.

Just curious more than anything.

Sponsored

 

[Davexxxx]

To answer your question, yes.

In tow haul, PB won't go into electric only (unless in park) but it collects and sends electric motive power, same as normal mode.

You can see this in action on the power flow meter.

I experimented with manual shifting but didn't notice any difference in resulting mpg, or temps, so I set the cruise and let the truck do it's job.

Your observation of the turbos could be so. It makes sense.

 

[Goldeneye36]

This is my understanding of how the PB drives in general. I just got an OBDLink MX+ and have been just monitoring things while driving to see what the truck's systems are doing and it definitely uses the hybrid motor to assist the engine and reduce the need for boost in just normal driving around town. I rarely see any boost on the dash gauge even with moderate acceleration when I'm just out and about and the PIDs on the OBDLink app confirms this by showing the hybrid battery discharging during acceleration then back to charging once cruising along. It's really fascinating (for my nerdy self anyway) to watch and I still need to play around with the other drive modes to see if they change anything.

I can only imagine that the effect is greater while towing, which is probably what you were seeing.

 

[MM in SouthTX]

When I drove an EcoBoost, people on forums would say it should be named Eco or Boost. It was pretty true. If you could avoid using the turbos, it was fuel efficient. Use turbos, and it was as bad or worse than the V8.

So maybe the primary role of the electric motor (in terms of fuel efficiency) is to avoid using the turbos. Instant torque is where the electric motor excels, so it fits nicely at the beginning of acceleration (or a hill) where torque is needed.

The OP's experience on a longer grade, where no boost was needed at first, then suddenly the boost appears, probably results from a depletion of the very small battery. The electric motor drops off and is replaced by the turbos.

I have never heard that higher RPM's keeps the turbos from kicking in. That seems to be the opposite of what turbos normally do.

As far as towing in manual, I always did it with a 6-speed. With the 10-speed, there's just too many gears! I tow in drive and Normal mode unless I feel like the truck is working too hard, in which case I switch to Tow mode.

One more thing on an already TLDR post--the main reason to tow in manual is to avoid overheating the transmission. This would occur when the "overdrive" would kick in and out over and over. Suburbans were notorious for burning up transmissions. Not at all sure this is an issue with newer transmissions with more gears. I would recommend you just tow in Tow mode and Drive (not Manual) and keep an eye on your transmission temp. If it rises, switch to manual and try to peg it to one gear for a while. Temp should drop.

 

[Goldeneye36]

I have never heard that higher RPM's keeps the turbos from kicking in. That seems to be the opposite of what turbos normally do.

It depends on what sort of conditions you are driving in. If you find yourself in a high gear/low RPM situation using boost to maintain speed, let's say 65mph for example, you can use less fuel and run a bit cooler by downshifting or locking out the high gears which increases your RPM and lowers the boost to compensate. To simplify, maintaining a specific speed requires a specific amount of HP/torque output. You can reach that number either through high boost/low RPM or low boost/high RPM but as long as you are making that number you will maintain your desired speed.

 

[MM in SouthTX]

It depends on what sort of conditions you are driving in. If you find yourself in a high gear/low RPM situation using boost to maintain speed, let's say 65mph for example, you can use less fuel and run a bit cooler by downshifting or locking out the high gears which increases your RPM and lowers the boost to compensate. To simplify, maintaining a specific speed requires a specific amount of HP/torque output. You can reach that number either through high boost/low RPM or low boost/high RPM but as long as you are making that number you will maintain your desired speed.

Interesting concept. Not sure how you define low and high RPM. I consider low RPM's to be below 2,000. I guess it would be possible to run high RPM's with a light accelerator touch and avoid boost, but isn't that what Tow mode does? I find that it sets the transmission shift points so that the RPM's never drop below 2,000, thus avoiding low RPM situations. I never thought that trying to run RPM's of 2,500 or more would be more efficient, but maybe there is a sweet spot somewhere up there with a given load and a given need for torque. I've never tried to chase it with the 10-speed because I haven't towed long distance with it yet. Might be worth a try.

 

[FaaWrenchBndr]

Interesting concept. Not sure how you define low and high RPM. I consider low RPM's to be below 2,000. I guess it would be possible to run high RPM's with a light accelerator touch and avoid boost, but isn't that what Tow mode does? I find that it sets the transmission shift points so that the RPM's never drop below 2,000, thus avoiding low RPM situations. I never thought that trying to run RPM's of 2,500 or more would be more efficient, but maybe there is a sweet spot somewhere up there with a given load and a given need for torque. I've never tried to chase it with the 10-speed because I haven't towed long distance with it yet. Might be worth a try.

mileage will be better, locking out the overdrive gears when telling versus not doing so

 

[HammaMan]

The electric motor helps when power is called for but the battery only has around 400Wh worth of usable energy after some healthy regen. Works best in conditions when there's regen potential like rolling hills at a speed where aero isn't the limiting factor (like around 65mph or less). If you see boost continually building, drop a gear. It's eco or boost so stay out of boost. I've been in hills where manually going between 8 and 10 netted a 10% mileage bump. Not really worth micromanaging to that level though unless you're just looking for something to do.

 

[Samson16]

It depends on what sort of conditions you are driving in. If you find yourself in a high gear/low RPM situation using boost to maintain speed, let's say 65mph for example, you can use less fuel and run a bit cooler by downshifting or locking out the high gears which increases your RPM and lowers the boost to compensate. To simplify, maintaining a specific speed requires a specific amount of HP/torque output. You can reach that number either through high boost/low RPM or low boost/high RPM but as long as you are making that number you will maintain your desired speed.

And in normal mode with cruise control on the PB will keep rpm and gear selection stable and just use boost to maintain speed.

 

[TheWrench]

You know it's funny you guys mentioning this. I came from a 2011 3.5L eco, and that truck was ALWAYS in boost. If you thought about touching the gas pedal, it would go into boost. With my 2023, I thought maybe Ford used bigger turbos or something because boost was coming in so late. After reading this thread, I assume now the truck was using the electric motor and leaving the wastegates open for a while before transitioning to closing the wastegates and bringing in the boost. Makes perfect sense now.

Sponsored