4482

I just heard about the TC005-03R ECM calibration. I'm going on a 6000 mile trip in a couple weeks. I have an appointment at my Lexus dealer for a tire rotation/balance and oil change in a couple days. They are also willing to do the new (for me anyway) ECM calibration. I'm wondering if I should let them do it or not. I've put 15000 on my car and have learned to live with the transmission the way it is now.

I can't help but wonder if there are a multitude of reasons I should go ahead and let them do the calibration?

Has anyone had this done and been unhappy with the outcome? I do know that the "transmission memory" gets reset to a learning mode initially. My car is a 05 AWD RX330.

Thanks in advance.

Lil4X

If you are experiencing rough shifts, your dealer can reflash the ECM to the latest transmission logic in a matter of minutes. Yes, you will have to "retrain" your transmission, but all that requires is for you to drive normally. I had my early-production 330 reflashed a few months after purchase because the transmission was stumbling at the 1-2 and the 2-3 shifts at part-throttle or worse, if I was easing off the throttle, causing a "premature" upshift. The new program fixed everything just fine. A handful of people on this forum have been unhappy with one of these updates or another, but for 90% of our members who have had it done, it has either solved the problem or made no appreciable difference. The few in latter group probably didn't have a serious problem going in.

My service manager also explained that using premium fuel will improve what we think is shift quality too (he drives an RX as well). It seems the ECM is "mapped" for premium fuel, and on acceleration it dials up the spark advance. If you are running a lesser grade, any spark "knock" detected will retard the spark to prevent knocking - which is exactly what it is intended to do. However, retarding the spark has an effect similar to lifting the throttle, and if it occurs as the transmission reaches a shift point, it can cause a rough shift because the ECM is getting conflicting commands.

Not to turn this into yet another "What grade fuel should I use?" thread, but your ECM is optimized for premium fuel, but thanks to those knock sensors, your engine can run happily on just about anything that will both pour and burn (as Lexmex has proved with Pemex gas). Premium fuel eliminates the ECM's having to "refine" the advance curve as you drive, and may give you somewhat smoother performance. My crude empirical research, based on the RX's average fuel consumption on the trip computer, indicates a two mpg improvement when using premium - making the additional cost a wash. A couple months ago my service manager and my salesman independently told me the same thing. Based on my experience, there may be something to it.

Todd

Coming from a 99 300 to an 06 330 I was disappointed to say the least that the transmission, although better, still was subpar for any vehicle, not just a Lexus. This has been a point of irritation with me. But in learning to make the best out of it here is a theory and something that made a noticable difference for me.

When the vehicle was new we drove very, very conservatively during the break-in period as recommended. No jack rabbit starts, high speed driving or such. Now, as the transmission is an adaptaive one it "learns" your driving habits and does some sort of stupid wizardry and comes up with its idea of proper behavior for your driving style.

Well, after complaining about the way it shifted and learning it had the latest ECM software the service adjustor reset it and told me to "drive it like I stole it". Which I did for a week while my wife was out of town (since its her car). I mean I drove it hard with very fast launches off the line and kept it there up through the gears. Well, the result under more sane driving behavior was that the transmission shifted smoother and lacked most of the jerkiness and the confusion it displayed at times before.

Therefore, my theory is that by babying the car (which you seriously should do) during the breakin period you are teaching the ECM a different than normal driving behavior. So, an idea a couple of you should try perhaps so we can prove or disprove the theory is reset the ECM and drive it like a bank robber for a week or so and then see if the transmission performs better afterward.

On the old 300's you could reset the ECM by disconnecting the battery for a couple hours or so. Does anyone know if this works on the 330 or 350 or is there a better way to do it.

PEK

I had ECM reset about 3 weeks ago & it was working like new(no hesitation). But this past weekend I drove it, the problem seems to recur again (hesitate from 2-3). Is that possible? Do I need to have it reset again? I have to tell you that my wife is a primary driver & I just use it during weekend.

Lil4X

Is it hesitating with your wife driving? Ride with her for a few miles on suburban streets to see if her driving style (throttle application) differs significantly from yours. It may be "learning" her idiosyncrasies, so that when you take the wheel the ECM is not anticipating your set of control inputs.

Memo to Lexus: connect that transmission memory to the seat position memory along with radio station buttons, climate control settings, and mirrors.

larryp

I had the ECM Calibration last week on my '04 RX330 and the improvement in shifting was dramatic (for the better - no more hestiation!). I highly recommend it.

PEK

Thanks Lil4X, will try that this weekend.