How bad is auto start-stop? - Ford F150 Diesel Forum
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Old 10-31-2019, 11:19 PM Thread Starter
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How bad is auto start-stop?

How much, if at all, does the auto start-stop harm the diesel engine?

Outside of any debate about inconvenience or personal preferences (please avoid that discussion here and also avoid how to disable ASS) what is the damage to the engine itself by simply letting it shut off as often as it wants? I've done some googling but haven't found much of a solid, factual answer. Finally, anyone roll with ASS and get a little better fuel economy, if so, any idea how much better?

Judging by the numerous "how to disable" threads across the internet, folks aren't a fan and I get that. However, I'm interesting in learning more about how this feature affects the longevity of our engines.

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Old 10-31-2019, 11:32 PM
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@Kingford - as we have learned, you need much more CCA (Cold Cranking Amps) in your battery to turn over a diesel engine compared to a gasoline engine, due to the higher compression ratio in diesel engines. In addition to a larger battery on a diesel engine, you also have a significantly larger starter for the same reasons. Coupling all of this together, I think ASS on a diesel engine is a STUPID idea -- I have non-diesel owning friends at work asking me why Ford would put ASS on a diesel vehicle! I don't believe the perceived savings in fuel economy is worth the extra wear & tear on your battery, starter, and most importantly your engine, especially given the shake and rattle you get when ASS kicks in. You can probably guess what my very first FORScan mod was by now...

2018 Ford 150 PS Diesel Platinum FX4 in Ingot Silver w/BuiltRight Rear Seat Release, Gatorback F150 Splash Guards, Lloyd Custom F150 Luxe Carpet Mats & Titan 40 gal replacement fuel tank
FORScan mods: Auto Start/Stop Disabled, Bambi mode, Digital Temps Above Gauges, DPF Full %, OCR (Operator Commanded Regen) and Heated & Cooled seats on Home screen
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Old 10-31-2019, 11:58 PM
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I’m of the belief ASS only fluffs the manufacture’s bed in regards to mpg ratings... maybe. I also believe it’s unnecessary wear and tear on the starter regardless if it’s heavy duty or not. If it’s not used, or used less, it wears less. Duh! I finally believe that having ASS kick in when I’m at a stoplight in regeneration, is a BAD idea. Therefore, I added the ASS eliminator shortly after I brought Toothless home.
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Old 11-01-2019, 07:18 AM
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My concern here in FL is the turbo, as well as what the others have said above. They run at such a high temp and constantly shutting it down has to be tough on the hot bearings and motor oil.

I put the little device in that eliminates it.
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Old 11-01-2019, 12:20 PM
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Ass syatem

Dunrollin I was going to pm you but dont know how, what device can i use to disarm this pest. also if you can contact me i would like to ask you some questions on these newer diesels.Thanks Jerry Adams

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Old 11-01-2019, 12:28 PM Thread Starter
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Automakers will tell you the battery and starter are prepped for the more starts and it makes sense that starters can be built to last longer and be better configured for more starts. Of course, it's totally obvious that repeat starts can't be good for the starter though, haha. I'm willing to take the automakers at their word here but even if the starter does have a shorter life span that would be nothing compared to any wear caused to the engine itself and that's more my question here.

I know of good ol boys with farm equipment and they never shut them off if they're walking away for a bit. I know ol timers that will leave their beloved truck idling in the parking lot too. I'm curious to know what those folks know. I'm sorry, but I seriously doubt all these folks were simply worried about their starters ..

As for the mpgs, I'm really interested in real world results but a little googling will tell me an idling 3.0L diesel will consume around 0.2* gallons of fuel an hour. That's not a lot and if ASS saved us 0.5 gallons - that's 2.5 hours of idling and ~$2 saved at the pump - it would translate into approximately a 0.5 mpg increase. Pretty pathetic BUT I've also read that an idling diesel produces a less clean exhaust than at load. How much quicker does our DPFs fill up with increased idling time? What about the increased oil wear, I'm surprised idling time is treated differently in Ford's oil life calculator than running time.

I haven't thought about the turbo, that's a really good point and it's shocking that during regen the engine would shut off! The easy answer to this is pay the negligible increase at the pump and feel good knowing the bits under your hood are better off. I'm just curious in the details here.

*Source for idling consumption: https://www.energy.gov/eere/vehicles...iesel-vehicles

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Old 11-01-2019, 12:31 PM Thread Starter
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I would rather this not degenerate to a "how to shut it off" thread, there are tons of those out there @Gradymaci . With that said, he's probably referring to the ASS eliminator: https://www.autostopeliminator.com/c...top-eliminator

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Old 11-01-2019, 01:56 PM
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Thanks Kingford..Need all the help I can get..But I waz the fastest in the slooow class.

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Old 11-01-2019, 02:49 PM
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I don't have any empirical data, but I would guess ASS is on the order of 0.5 MPG or less, depending on the types of roads your are driving; e.g. ASS isn't going to buy much for someone who is driving 95% highway miles. ASS is definitely one of many tactics Ford and other auto-makers are employing to raise their overall fleet CAFE fuel economy averages.

Another tactic/trick is the special F150 oil that our engines take. You can read up on previous threads on this new oil specification; e.g. What oil are you guys using? that our engines require and if you look behind the spec, you will find that this recommended oil is a thinner oil with better lubricating qualities for tighter precision engines. Why would they go with a thinner viscosity oil? Because it offer better engine protection? No, they claim is raises their average by 0.5 MPG because it is easier to pump a thinner oil thru the engine and offers less friction/resistance. Some owners are choosing a thicker viscosity oil for better engine protection in lieu of the MPG savings....

Couple ASS + WSS-M2C214-B1 oil spec = Ford can now claim to the government an aggregate 1 MPG increase in the average MPG for the F150 PS Diesel, which helps raises their overall fleet average. This is all towards gaming the federally-mandated CAFE averages.

Since ASS is just to make the government happy AND you can disable it by hitting the button on the dash, using ASS is not required but rather optional. Given ASS doesn't compute with my engineering training and degree, I chose to permanently disable this option.

2018 Ford 150 PS Diesel Platinum FX4 in Ingot Silver w/BuiltRight Rear Seat Release, Gatorback F150 Splash Guards, Lloyd Custom F150 Luxe Carpet Mats & Titan 40 gal replacement fuel tank
FORScan mods: Auto Start/Stop Disabled, Bambi mode, Digital Temps Above Gauges, DPF Full %, OCR (Operator Commanded Regen) and Heated & Cooled seats on Home screen

Last edited by jmperlik; 11-01-2019 at 02:54 PM.
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Old 11-01-2019, 05:45 PM
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Quote:
Originally Posted by jmperlik View Post
Since ASS is just to make the government happy AND you can disable it by hitting the button on the dash, using ASS is not required but rather optional.
I think the ASS is only a public relations ploy and a psychological feel good trick.

I think those that remove something that they can be disabled, because they feel it's useless, is also a psychological feel good trick.

At 75 years old I let it do whatever it wants to do.
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