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2nd to 1st shift (jerk, push etc symptom)

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2nd to 1st shift (jerk, push etc symptom)

Old 01-09-19, 10:46 AM
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BlueRCF10
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Default 2nd to 1st shift (jerk, push etc symptom)

Hey Guys,

As you might know, Lexus/Toyota has an ECM issue they never seemed to have fix for various makes/models which displays itself in a less than smooth downshift from 2nd to 1st gear. Some people notice it some people don't or some people just accept the car as is as one if it's characteristics. Many Lexus forum members have reached out to SIA Electronics in Illinois to have their ECM fixed and it has worked. I am currently in the process of doing this for my 2008 GS350 as it has this issue. I'm confident that the issue will be resolved and look forward to having this issue fixed.

On the other hand, I noticed my RCF does this as well as I recognize the symptoms from my GS. I contacted SIA and they do not have a fix for this yet for our model yet. I was wondering if anyone else has found any solution to this? Once I take my car out of storage, I'll be re-flashing the computer at the dealer to re-learn my driving styles etc as the car is new to me. But through research, I've read that this does not fix the issue. The car shifts beautifully and gracefully through all the other gears. My warranty is up in June of 2019 and I'll try to somehow get this fixed through the dealer but when I mentioned this to them they sorta acknowledged the issue and said that there isn't a fix.

Love the car but this is my only minor issue with it. I doubt passengers feel this subtle symptom but it personally bugs me.

Let me know your thoughts....
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Old 01-09-19, 11:21 AM
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GunnyFitz
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Hmmm, never once thought this was a problem since shifting to 1st gear means you are extremely close to a stopped position. I personally don't use this gear for Engine Braking.
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Old 01-09-19, 11:25 AM
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Originally Posted by GunnyFitz View Post
Hmmm, never once thought this was a problem since shifting to 1st gear means you are extremely close to a stopped position. I personally don't use this gear for Engine Braking.
You made me doubt myself and it could be from 3rd to 2nd. Regardless itís there and itís subtle but bothers me. It should be smooth shifting throughout all the downshifts. Itís bothersome to me just anticipating that little hiccup.

Iím talking about this in full auto mode. No engine braking involved.

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Old 01-09-19, 12:44 PM
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The GS F does this too. My IS F does not. I just assumed it was a different TCU with "updated" code and it is normal for the GS F to do this.
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Old 01-09-19, 12:54 PM
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Originally Posted by lobuxracer View Post
The GS F does this too. My IS F does not. I just assumed it was a different TCU with "updated" code and it is normal for the GS F to do this.
Various Lexus models do this. Some do and some donít. Lexus misdiagnosed many cases and people paid for new trannys and new ECUís. Ridiculous actually.

To me, Iíll accept it until SIA or another company has a fix. Iíll re-flash it under warranty for now....

Last edited by BlueRCF10; 01-09-19 at 12:58 PM.
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Old 01-09-19, 02:13 PM
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Originally Posted by lobuxracer View Post
The GS F does this too. My IS F does not. I just assumed it was a different TCU with "updated" code and it is normal for the GS F to do this.
I experience rough shifts usually from 2 to 3 on my GSF.
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Old 01-09-19, 02:46 PM
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Originally Posted by finny76 View Post
I experience rough shifts usually from 2 to 3 on my GSF.
Rough upshift from 2-3? Or downshifts from 3 to 2?
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Old 01-09-19, 07:27 PM
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Up shifts from 2-3 i.e when I'm in gear two and then it just puts it in 3 with a Jerk.
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Old 01-09-19, 07:33 PM
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Originally Posted by finny76 View Post
Up shifts from 2-3 i.e when I'm in gear two and then it just puts it in 3 with a Jerk.
Thatís different from this cause but Lexus trannys are pretty bulletproof in general.

Iíd get a ref-flash and a tranny oil change (Check to see if itís recommended).
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Old 01-11-19, 04:32 PM
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You should never downshift from 2nd to 1st unless you are going incredibly slow AND slowing down.

This is is a normal behaviour even for a manual transmission.
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Old 01-11-19, 04:43 PM
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Originally Posted by brendanf View Post
You should never downshift from 2nd to 1st unless you are going incredibly slow AND slowing down.

This is is a normal behaviour even for a manual transmission.
As I clarified above, itís from 3rd to 2nd most likely.
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Old 01-11-19, 05:04 PM
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Well thatís a bit different.

The RCF is a bit strange in how it handles the downshifts from one gear to another.

It looks at several things,

1. Is the car up to temperature yet
2. How hard are you braking
3. And, where will the revs land if it rev matches.

Ive found until the car is at operating temp, most of the fun stuff is locked out and it drives in a boring fashion.

Brake pedal pressure seems to be the key in my experience. If Iím braking hard enough then I will get a nice throttle blip and rev match from the ECU even in AUTO.
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Old 01-11-19, 05:47 PM
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Originally Posted by brendanf View Post
Well thatís a bit different.

The RCF is a bit strange in how it handles the downshifts from one gear to another.

It looks at several things,

1. Is the car up to temperature yet
2. How hard are you braking
3. And, where will the revs land if it rev matches.

Ive found until the car is at operating temp, most of the fun stuff is locked out and it drives in a boring fashion.

Brake pedal pressure seems to be the key in my experience. If Iím braking hard enough then I will get a nice throttle blip and rev match from the ECU even in AUTO.
I agree. This symptom Iím describing usually occurs when the car is fully warmed up.
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Old 01-11-19, 06:42 PM
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Since I drive in manual and sport + all the time - I've memorized the best down shift points for the ECU to perform a "proper" rev match and blip duration:

From 4 -> 3: 90-100 KM /h
From 3 -> 2: 65-70 KM /h
From 2 -> 1: 35-40 KM /h

These downshift points are useful only when the engine oil and coolant are at optimal temp (triangles in the middle). You'll know when the car is ready for a beating once your G-Sensor / Brake and Accel sensors are showing values and aren't grey'ed out under the F menu. The red-line crawling back to 7300 RPM is not a good indicator.

You have to be very very careful shifting from 2 -> 1 at a speed slower than 35 KM/h - the downshift will be rough and the car will jerk unnaturally. Aim to downshift to 1 near 40 KM/h.

As for upshift - as close to red-line / limiter as your heart desires
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Old 01-11-19, 06:45 PM
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Originally Posted by 3IS350Guy View Post
Since I drive in manual and sport + all the time - I've memorized the best down shift points for the ECU to perform a "proper" rev match and blip duration:

From 4 -> 3: 90-100 KM /h
From 3 -> 2: 65-70 KM /h
From 2 -> 1: 35-40 KM /h

These downshift points are useful only when the engine oil and coolant are at optimal temp (triangles in the middle). You'll know when the car is ready for a beating once your G-Sensor / Brake and Accel sensors are showing values and aren't grey'ed out under the F menu. The red-line crawling back to 7300 RPM is not a good indicator.

You have to be very very careful shifting from 2 -> 1 at a speed slower than 35 KM/h - the downshift will be rough and the car will jerk unnaturally. Aim to downshift to 1 near 40 KM/h.

As for upshift - as close to red-line / limiter as your heart desires
Useful info for sure! But Iím driving it in auto ďnormalĒ mode when this occurs. Itís a know Lexus/Toyota issue and they donít have a fix for it unfortunately.
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