Break-in period...what's really going on?
 

Sorry for the dumb question.

I've heard from various people (and at different times...not just with this car), that every new vehicle has a break-in period where you are supposed to reduce the strain on the engine...lower revs, less acceleration, etc. Usually 1000-1500 miles.

But is anything actually programmed into the ECU for this period? Meaning, after you click over a certain mileage does something physically change? Is it programmed to run more rich during this time (some people report that the gas mileage is lower during break-in)? Or is it basically just a guideline to follow to slowly break-in the engine?

Just something I was curious about. I'm assuming nothing changes, and I've even heard from some people that the "trial by fire" method is actually the best way to go (meaning, go full out any time you want from the beginning). Just heard a lot of bits and pieces to the puzzle, but never the full picture.

Thanks for any answers!

http://www.popularmechanics.com/_mob...k-in-a-new-car

I know very little about cars, the above link is a good read.
:) hope that helps some

So that's the stuff you should do, but what I'm interested to know is if there is anything in the ECU that is different for the first thousand or so miles? On one hand, it would make sense that it would be engineered that way (to prevent poor break-in, allow it to run more rich or retard the timing a little), but I have never seen any proof that it works that way. On the other hand, I also think it would add unnecessary complexity to the system. So, I guess I can see how both ways would be beneficial, but I'd be interested to know for sure which is true.

All I know is, is that the car manual suggests you not rev past 4,000 RPM for the first 1,000 miles unless it is an emergency. Seeing as they (Toyota/Subaru) built the car, I will follow their guidelines. And my gas mileage was around 28.5 MPG during break-in. Can't say I've seen better gas mileage since after the break-in :lol:

I subscribe to what you call the "trial by fire" method, but that makes it sound like we flog the car to break it in, not necessarily what happens. It's more to do with progressively using the engine's combustion power and heat to seat the rings instead of letting them gently graze the cylinder walls at low rpm. It's always worked for me and none of my engines have ever consumed oil or had problems, bike or car. Then again I focus on driving/riding smoothly, don't slam gears, and always monitor engine temps before I do get aggressive.

My wife's car was driven gently from day one, and it would consume oil noticably, could be half to one quart low between oil changes.

Break in has become some mysterious unknown voodoo that everyone has WILDLY different ideas of what should be done. You have the book quoters and the rebels. I personally believe the "drive gently for 1000 miles break in" stated in owners manuals is for three reasons: 1- The DRIVER can "break in" while learning a new vehicle, 2- If there's any mechanical problems not detected during manufacturing that may catastrophically fail, it's MUCH safer to discover them while driving gently rather than at WOT or in a mad crayzee dryft. And 3- because it's what they've always said; changing it now would be hugely controversial.

As far as the ECU is concerned, I am extremely, EXTREMELY skeptical that there's any programming specifically for break in. Anything is possible, but this is highly improbable. I believe the changes people notice are either completely imagined, or they are actually noticing a difference in the machine as a whole running a bit smoother. I think a sudden noticable boost in power is from the ECU adjusting it's timing or from a cool day, not the machine suddenly being broken in.

No the ECU acts the same whether the car has 500km on it or a million.

The break in period is allow wear surfaces to "mate" to eachother. People report increased fuel economy over time due to reduced friction between these surfaces. Ring seal also slightly improves for the first couple thousand km.

Many people who flogged their car report black oil after 1000km or so. I did the "proper" break in which is not driving like my grandmother, but not being too hard on it either. My oil looked like new at 2000km.

You tell me which one sounds better for your engine. I worked in an automotive machine shop for 6 years and finished my career there as general manager. I've seen hundreds of engines get broken in and the "not too easy, not too hard" method always seemed to work out the best.

** This is the simplified explanation btw.

Basically, the short term and long term fuel trims are still being calibrated in the first 100 miles or so whenever the ECU is reset. Thats why during these miles the car may or may not get the advertised gas mileage.

Moderation in everything, even moderation!

agree with above.
I believe running car moderately, i.e 4000 rpm during break-in period helped me to develop how I run the car after break-in.

Now I always drive around 3000-4000 RPM daily. Sometimes I do love to drive around midnight and run it to 7000 rpm.

Whatever you choose, just ensure to warm up your engine.

For me I always wait until the temp needle reach the 1st bar.

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There's 2 schools of thought, "take it easy" and "run it hard". They both have groups of believers and I have yet to hear anything about one being better than the other. All of their cars still work.

Just drive it. It's a modern car, and it's built with precision. Plus it comes from the factory with around 7 or so miles usually, so it's not like a brand new crate motor. Don't go crazy with it. Or do, like that guy who started tracking it after 500 or so miles. The engine will be fine.

I hear that the break in period is mostly for the clutch to break in, but I didn't know that until after break in and I treated my clutch poorly. It's still fine. It's a car made by Subaru and Toyota. Think about all the Subarus and Toyotas you see on the road that have a million miles on them, where the owners never even heard of "proper break in procedure".

I learn about the break in period a little to late before I ran hard with my car.

But yeah I would wait for the 1000 miles and try not going pass 5 rpm.

Same here.

Can't add much to the OP. But I will say when it comes to driving the car hard, I've always babied my new cars and never really allowed over 3k for daily driving, but with the FR-S I always take it out further and it feels just right. My gas mileage has actually improved over low rpm cruising.

Engineers get pissed when people don't follow their instructions because stuff usually ends up broken.

There is very little easily accessible information/data/research that is actually valid. In the end you can trust whoever you like, odds are no problems (or very few) will occur either way and it has much more to do with the mechanicals than the ECU imho.

I did a progressive break in for my engine.
0-250 miles: Under 4000 rpm.
250-500 miles: Up to 5000 rpm.
500-750 miles: Up to 6000 rpm.
750-1000 miles: Up to 7000 rpm.

Between 250-1000 miles, it was taken over 4000 rpm in moderation and only for the first couple gears each time. Honestly as long as you aren't constantly redlining the engine you should be fine.

As far as ECU changes, only a Toyota / Subaru engineer would likely be able to answer that. But I highly doubt there is anything hardcoded into the ECU to act a certain way until the car reaches X amount of miles. That would be silly, actually, when you consider an engine swap. The car may have over 1000 miles, but the engine wouldn't have any mileage.