ECO start/stop feature misunderstanding or misinformation

[Mersovod]

The damage to the engine from long idling is much greater than from the ECO function. From a technical point of view, there is no harm to the engine. It's another matter when this function annoys you. So activating the “last mode” mode is very convenient.

 

[vannuys]

The damage to the engine from long idling is much greater than from the ECO function. From a technical point of view, there is no harm to the engine.

I see this asserted in a lot of places. But very difficult to find actual studies, let alone studies on a particular brand or engine model.

To decently test this, I imagine someone would need to buy 2 identical engines, and run them extremely long time on identical load patterns. Then they can be torn down and inspected. Not very easy to simulate many years of driving. Presumably manufacturers do this, but I expect they are mostly interested in "will this engine reach warranty life?" and not so much "will this engine operate 200k miles over 15 years?"

The main legitimate-looking concern I've seen anyone raise is that the oil may quickly seep out of crankshaft bearings while the engine is stopped, and then those unlubricated restarts would wear the bearings faster. Maybe that's untrue, or maybe the bearings would still outlive the rest of the engine anyways, but that would still depend a lot on engine design i expect.

The next step is "so what if your bearings get a little worn?" maybe on some engines it's no problem and maybe on others they will cascade failures with even a slight decrease in bearing tolerance.

 

[Mersovod]

1. Oil does not leak from the bearings (pressure lubrication)
2. The engine is hot (the greatest wear on the engine occurs during a cold start)
3. ECO is a function involving approximately 8 ECUs, which, like on a space station, monitor the state of on-board systems.
4. The starter is structurally VERY reliable and durable.
5. The ECU remembers the position of the shafts (crankshaft and camshafts) relative to TDC and during a “hot start” it injects fuel into the corresponding cylinder; the starter itself actually only helps a little to turn the engine. That is, the start is made by injection and not by the starter.
Notice how quickly modern engines start in ECO mode.
In short, all the talk about the harm of ECO-START is empty chatter. Over time, people will get used to it and all questions will naturally become a thing of the past.

 

[Prophetuk]

So from the research I have reviewed, there are 2 reasons for switching it off and on and it's dependent on driving conditions.
1) If you are primarily in a metropolitan area the usage of this feature would be higher if you are in a ULEZ/Congestion zone often you may be impacted more than if you are rural based.
The high volume of stop-start traffic means you are energizing and engaging the starter more often. If you have a lot of LTNs (Low-traffic networks) even more so.
2) it's also dependent on WHEN the stop-start engages from COLD the start is harder and if you are in traffic off the bar the oil will take time to
a) circulate & b)get up to temp so again increases engine wear due to low speeds and less idling (though small) will have an impact and eventually take a toll on the engine.
If you follow the old method of starting and running the engine for 5 minutes before setting off should offer more protection as well as using finer oils and regular servicing should negate the need to use stop-start.
I have also heard in high spec turbos models they impact the turbo units more so than on V6s or eco models.

 

[currumblera]

I usually turn off the start/stop function because in traffic jams, heavy traffic... it is constantly turning the engine on and off. This is terrible for the battery and starter motor.

 

[lmdtm]

Most user manual refer that you should turn off ECO mode in heavy traffic.
The ECO function is designed to work in stops like a stop light or junctions, not to work constantly in traffic.