kuuqi

it's been taught to me that during break in is to take it easy for the first 500-1000 miles but within this period is to do some WOT at which case you should rev it to 3000 then engine brake 4000 and let it engine brake, 5000 then engine brake and so on until redline. Basically the engine deceleration has a pulling force along the rings to seat them.

but i've also been taught to baby the car for the first 1000, drive it hard because machined products now are more precise, etc. I would say from everything I've learned, i think WOT with engine braking after about 50 miles (or even skip this part) is best as a better seated ring can then smooth out a more perfect worn in shape instead of letting a not so well seated ring create different grooves (though sometimes microscopic) that the later correctly seated ring has to live with or resurface a bit.

jackblack7

I'm having trouble understanding this. How do you WOT, but not go over 3000 rpm? Do you just floor it for less than a second?

juice14

true hehe.
Id say drive like a baby to get better gas milage. and if you wanna go to the track you reset the ECU couple days earlier and drive it hard.
I still believe the car is faster with the ECT on.

juice14

22 yes
21 no.

Kurtz

iTrader: (1)

Your belief has been tested, measured, and documented as incorrect however

juice14

Im not talking about track times. Im sure the ECT off gets better track times for whatever reason. but i feel better throttle response with the ECT on at highway speeds, when passing from 40 to 60, etc.
I ve heard from everybody that goes to the track that ECT off gets better times, specially from caymandiver who ahs the fastest one I think.
but like I said, throttle response, at WOT and also when just pressing the pedal slightly...I fele better response. thats just me

Gtidan

Look at it this way................Are any of the poster here engineers? I doubt it so take any of the bs with a grain of salt. Opinions are like a..holes, everyone has one......

And............Lexus engines are run in prior to being installed.......have you not seen their recent ads?

gtg941f

On that note, yes I am an engineer. To all the people saying WOT from the get go, sure it has the potential to be quicker. However, it'll be quicker for only so long and will result in engine failure much earlier than it needed to be. It's all based around the simple concept of yield strength. Early in a materials life, it's susceptible to plastic deformation if too much stress is applied. In babying the car from day 1, you're keeping the stresses within the elastic region and the material is able to recover. Sooo, all I'm trying to say is, if you don't plan on keeping your car for much near/over 100k miles, go ahead and go WOT all day long. If you'd like to have a potentially slower engine that lasts much longer, be kind to your car and break it in properly. Be advised that Lexus doesn't just write this **** in their manual to be mean to the people who want to race right off the lot.

Besides, a majority of the speed dependence for newer cars is in the ECU. Baby your car for the first 1000, reset the ECU and then go nuts would be the most sound advice.

lobuxracer

iTrader: (2)

Is this based on practical experience or are you just quoting a materials science text?

If you look at what I recommended it isn't go WOT off the lot, and never has been. It's a simple procedure to increase the thermal load on the pistons progressively in about an hour. Pistons are highly subject to plastic deformation because they are in a near plastic state at WOT. Progressively increasing the load on them while giving them the opportunity to cool between heat cycles helps ensure they DON'T experience plastic deformation.

I've included a dyno of my Supra with 148k miles on it to demonstrate it works. I've built quite a few other engines equally long lasting, but this one was built by Toyota, and is still performing very well.

No, the ECM does not affect "performance" of the engine, it affects the shifting patterns of the transmission. Fuel and ignition timing will not be affected by any pattern of driving, only by feedback from the O2 sensors and the knock sensors. Saying an ECM reset will change the engine's performance is completely unsupported by any practical experience.

Pnuge88

iTrader: (1)

its true indeed my 250 FEELS faster and is more responsive compared to the IS's that come into work that were driven by old people

Clifton

You may be an engineer but you don't know anything about engine building. Break in has NOTHING to do with the reasons you have listed. Look at my previous post and then do some research on ring seating if you still don't believe.

juice14

I like the different points of view. I had no idea of most of what is being spoken here.

juice14

keep voting CL

RU514

**** only if I knew this since day one. I babied my car all the way till 1000 miles with MAYBE one run of WOT/redlining. I mean the 250 is slow as it is so I'm not saying it's going to be fast but I think I made it slower than it should be.

crazybuggy

i asked my dealer if there was a break in period and he said no not anymore. i wonder if this goes for the same with a iS250AWD...

whot about wear n tear? i mean yur car is brand new tho...