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As you probably know... the transmissions in our cars adapt to our driving styles. Something I don't understand is... what does the transmission change about itself to adapt to the driver? Also... what is it analyzing about your driving habits to determine how to change those parameters?
 
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The transmission changes the parameters in TCM (Transmission Control Module). In easy terms... it monitors how much you accelerate/de-accelerate. Let's say you always floor the car when you drive, the computer can hold a certain gear longer and vice versa. If i remember correct...the IS had a problem with slow acceleration from stop...there was a TSB for the computer to get re-programmed. This is the same for MANY sensors in a car.

Cars nowadays are so computerized that many problems are just reprogramming of a certain computer/module. Think of it as a "Windows Update" but for cars. I often get cars from private shops that they spend HOURS working to fix a problem and realize its a 20 min re-program from the dealer. Sucks but car manufacturers are getting smart....bringing thier cars back to the dealership. Hope that explains some stuff for you.
 
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I think Crester knows how the system works, what he wants to know is how it works in the vehicle.


Technical answer...just for Crester..cause it will bore the rest of you!


As with most electronically controlled transmissions "learned values" most likely controls the selinoid pressure, line pressure and throttle pressure, gear shift timing and lock up timing in response to the vehicles driving condition and engine operating condition detected by various sensors on the vehicle (Coolant temp sensor, VSS, Throttle position) then sends the signal to the transmission solenoid.
By selecting shift points (based on this information), the transmission provides the smoothest shift possible, despite temperature, fluid viscosity. It It will select the appropriate gear for the driving conditions at the time. This prevents gear shift shock, when starting off.

Resetting this function (ECM/ECU), puts the vehicle back into its mapped parameters, and it starts to learn all over again. This takes some time to do, as the computer monitors all of these functions and never stops.

Its alive!

Digger08
 
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LOL

Rep for the funniest thing posted on here in the last 6 months!

Digger08
 

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Did anyone here get the dealer reflash for the slow acceleration from a stop?

I consulted this with one of the Lexus/Toyota techs and they said it is only for the US vehicles... WTF?

I find my IS300 REALLY slow off the line, from stock to turbo.. I used to think it was the DBW system, but then I verified that the throttle position was always 100% when I go WOT at 1st gear (logging TPS voltage). Engine timing was appropriate and so was everything else.

The car still boogies from a stop, but compared to my other cars, the IS300 is pretty sluggish for 1st gear only. I was always wondering if doing a reflash actually solves anything, but who doesn't want almost free increase of acceleration?
 

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Did anyone here get the dealer reflash for the slow acceleration from a stop?

I consulted this with one of the Lexus/Toyota techs and they said it is only for the US vehicles... WTF?

I find my IS300 REALLY slow off the line, from stock to turbo.. I used to think it was the DBW system, but then I verified that the throttle position was always 100% when I go WOT at 1st gear (logging TPS voltage). Engine timing was appropriate and so was everything else.

The car still boogies from a stop, but compared to my other cars, the IS300 is pretty sluggish for 1st gear only. I was always wondering if doing a reflash actually solves anything, but who doesn't want almost free increase of acceleration?
I have had two reflashes - as being a manufactured early vehicle (2000), it does not specifically pretain to US cars - as all vehicles came from Kanto motor works, and the only difference is ride height and Km's and celsius in the dispaly read outs for Canadian vehicles.

Your tech is full of crap. It is based on your VIN identification, as most TSB's are (unless weather related).

It may be important to know that your 100% is only 100% of 70%, as I believe that this is where the throttle position takes over electronically. The first 30% is manually controlled. (Hope this is making sense). Perhaps an expert like Crester, can confirm this, although from your other posts you do seem to have good knowledge on our cars.

Digger08
 

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Yeah, I went over to the Lexus dealership just north of Yonge and Elgin Mills, and that's what they told me. Of course, rolling my 2001 IS300 into the dealership like 6 years too late (I got the car last year) makes them want to just "brush me off" probably...

I logged the actual TPS (throttle plate angle).. This will be the actual mechanical throttle plate angle and not the acceleration position sensor (cable/attachment sensor). Either way, maybe the car is just sluggish off the line carrying all that weight, and perhaps time to install an GReddy V-manage to play around with the VVTi...lol Thanks for the reply :)
 

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First thing I would try before anything else is a deep cleaning of the combustion chamber.

There is only a few products on the market that are thermally stable at the 500 degree or more temperature. Most over the counter cleaners do not deep soak this area, and generally burn off before proper cleaning can be done. This is because they all contain methonal (very efficient cleaner, but not stable and burn off before efficient cleaning can be done) you will need a petrolium distilate based cleaner. I'd almost bet my hat on this fact. Sea Foam is a really bad example of this type of product.

I would bet this may help restore lost performance, in this area. While it will not cure your hestitation problem, it will resolve any delays in WOT, as it probably is related to restrictions inside the combustion chamber.

I do know of a product, and have used this 2 times a year on my vehicle for the last 7 year. It is low VOC's and sensor and "O" ring safe.

Digger08
 

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Discussion Starter #10
The transmission changes the parameters in TCM (Transmission Control Module). In easy terms... it monitors how much you accelerate/de-accelerate. Let's say you always floor the car when you drive, the computer can hold a certain gear longer and vice versa. If i remember correct...the IS had a problem with slow acceleration from stop...there was a TSB for the computer to get re-programmed. This is the same for MANY sensors in a car.
Hmm... was there really a TSB reprogram for a a slow start??? I know of the TSB for a harsh 2-3 shift. You think you could see if you could find any info on the TSB you are talking about?
 

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Discussion Starter #11
I think Crester knows how the system works, what he wants to know is how it works in the vehicle.


Technical answer...just for Crester..cause it will bore the rest of you!


As with most electronically controlled transmissions "learned values" most likely controls the selinoid pressure, line pressure and throttle pressure, gear shift timing and lock up timing in response to the vehicles driving condition and engine operating condition detected by various sensors on the vehicle (Coolant temp sensor, VSS, Throttle position) then sends the signal to the transmission solenoid.
By selecting shift points (based on this information), the transmission provides the smoothest shift possible, despite temperature, fluid viscosity. It It will select the appropriate gear for the driving conditions at the time. This prevents gear shift shock, when starting off.

Resetting this function (ECM/ECU), puts the vehicle back into its mapped parameters, and it starts to learn all over again. This takes some time to do, as the computer monitors all of these functions and never stops.

Its alive!

Digger08
So it's reading how you apply the throttle... how you accelerate/decelerate... if the car is flat/climbing/going downhill... temperature... the various pressures in the hydraulic systems within the transmissions and then decides when to shift the gears to give the driver what it thinks you want... while still giving a relatively smooth ride?

I wish I could find a technical write-up on this...

The reason I am asking about this is... I'm trying to figure out my own transmission. At first I thought my transmission was too soft when I was driving it. So after I put a part on my car... I started driving really aggressively to try and get the car to adapt to the new part in an aggressive manner.

Well... now I have a quicker shifting transmission... and it at times feels like the car has the momentum of a runaway freight train. But... now some of the shifts feel harsher. If I drive gently... it feels smooth... and shifts are almost undetectable. If I drive really aggressive... it feels really great... and the transmission feels like a monster during shifts. But during what I'll call "medium pressure"... I can feel the shifts. It's as if the computer doesn't know whether to hold the gear or shift up... and then just kicks into the next gear. It's not really harsh... but I can tell it's shifting.

I like the quick shifts... but I wish it was a tad smoother during "medium" acceleration.
 

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Discussion Starter #12
It may be important to know that your 100% is only 100% of 70%, as I believe that this is where the throttle position takes over electronically. The first 30% is manually controlled. (Hope this is making sense). Perhaps an expert like Crester, can confirm this, although from your other posts you do seem to have good knowledge on our cars.

Digger08
I heard about that thing where the throttle isn't actually fully open when you floor it from a stop. Haven't verified it tho.

And yeah... our throttles are controlled by cable for the LAST 20-30%. The idea being that if the electronic throttle system fails... you can still drive your car. You'll need to push harder... but it'll still go.

The 2nd-Gen IS is different tho... I believe it has two levels of electronic throttle. So if the primary throttle fails... there's a secondary electronic system that will take-over.
 

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I heard about that thing where the throttle isn't actually fully open when you floor it from a stop. Haven't verified it tho.
I can confirm that on a 2001 IS300 E-shift, the throttle plate is physically 100% open when you floor it from a stop.

I have a spare IS300 throttlebody assembly, and I hooked up all the electrical connections to the sensors of the spare unit (but stock TB one is still physically installed in the car).

I turned on the engine and I can see the throttleplate action while the car is in gear (on the dyno). I placed it in "D" and floored the pedal, and the throttleplate opens 100% with almost no delay. The engine doesn't rev up of course because it is just controlling my spare TB.

So I ruled out the throttle plate angle for my sluggish starts. I plan on installing a cam gear and play around to open up a bit of overlap to kickstart the 2000-3000RPM range. The engine is just sluggish off the line for some reason.
 

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Where is peak torque on our cars?
I find my IS sluggish too. I compare it to the TDI Volkswagen I had - peak torque was at 1900 rpm. So even though the hp is wayy low, it pulled well.

I find our cars don't get moving until past 3000 rpm.
 

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peak torque @ 1900rpm is VERY LOW! Very usable for everyday driving.
 
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