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

Old 01-11-19, 06:54 PM
  #16  
3IS350Guy
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Originally Posted by BlueRCF10 View Post
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.
Oh I see - I guess in normal mode, the ECU is probably shifting at different (lower?) points than what i'm performing manually.

When I was testing the LC500, I noticed that they have this issue fixed. I shifted down from 2->1 at low speed with no lurch / jerk. I wish they could update our ECU with just this fix. Also, that other issue with the slight power cut out at around 2800-3000 RPM is really annoying when you're playing a smooth symphony with the exhaust.

Waiting for the LC F, but im probably going to jump into a MP4-12C by then.
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Old 01-12-19, 12:15 AM
  #17  
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I have the same issue in my gsf also. Iíve been searching for a solution but no fix so far. It is the final downshift when coming to a stop and usually happens around the 20-18 mph range and a slight jerk. It feels like a match rev downshift but the engine and trans are off by a few 100 rpms. Iíve brought it to the dealership and did test drive with service manager and he acknowledges the slight jerk but basically said with out a check engine light and code, Lexus wonít warranty to tear apart the trans and there is no new software upgrade available. A solution I have notice is that if you put your car in sports + mode it doesnít have this issue so mostly likely a ECM issue make sense. Hopefully a fix is found soon as Im with you that the anticipation of knowing the jerk is coming is very annoying and to the point of me almost trading in the car. And being a former ISF owner, that drivetrain/engine comb was super smooth. You could beat on that car and it wouldnít skip a beat.
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Old 01-12-19, 12:27 AM
  #18  
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Originally Posted by 916gs400 View Post
I have the same issue in my gsf also. Iíve been searching for a solution but no fix so far. It is the final downshift when coming to a stop and usually happens around the 20-18 mph range and a slight jerk. It feels like a match rev downshift but the engine and trans are off by a few 100 rpms. Iíve brought it to the dealership and did test drive with service manager and he acknowledges the slight jerk but basically said with out a check engine light and code, Lexus wonít warranty to tear apart the trans and there is no new software upgrade available. A solution I have notice is that if you put your car in sports + mode it doesnít have this issue so mostly likely a ECM issue make sense. Hopefully a fix is found soon as Im with you that the anticipation of knowing the jerk is coming is very annoying and to the point of me almost trading in the car. And being a former ISF owner, that drivetrain/engine comb was super smooth. You could beat on that car and it wouldnít skip a beat.
I don't drive the GS F enough to be really annoyed, but this is exactly my experience as well. Definitely the 2 - 1 shift, not 3 - 2, and the IS F does this like butter every time, eve with 160+k miles on the odometer.
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Old 01-12-19, 12:45 AM
  #19  
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Originally Posted by 916gs400 View Post
I have the same issue in my gsf also. Iíve been searching for a solution but no fix so far. It is the final downshift when coming to a stop and usually happens around the 20-18 mph range and a slight jerk. It feels like a match rev downshift but the engine and trans are off by a few 100 rpms. Iíve brought it to the dealership and did test drive with service manager and he acknowledges the slight jerk but basically said with out a check engine light and code, Lexus wonít warranty to tear apart the trans and there is no new software upgrade available. A solution I have notice is that if you put your car in sports + mode it doesnít have this issue so mostly likely a ECM issue make sense. Hopefully a fix is found soon as Im with you that the anticipation of knowing the jerk is coming is very annoying and to the point of me almost trading in the car. And being a former ISF owner, that drivetrain/engine comb was super smooth. You could beat on that car and it wouldnít skip a beat.
This is exactly it. Iíd contact SIA Electronics as they might have a fix for the GSF. But for the RCF there isnít any fix as of yet and Iím not sure I wanna be their first pilot test. Itís very bothersome to me personally and iíll be pushing SIA a bit to see if they could come up with a fix to this. The fact that my 2008 GS has this and my 2015 RCF also has it is ridiculous. Lexus shouldíve considered a fix for this since then...
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Old 01-12-19, 12:46 AM
  #20  
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Originally Posted by lobuxracer View Post
I don't drive the GS F enough to be really annoyed, but this is exactly my experience as well. Definitely the 2 - 1 shift, not 3 - 2, and the IS F does this like butter every time, eve with 160+k miles on the odometer.
Thats what I intially thought. The 2 - 1 downshift in auto mode.
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Old 01-12-19, 05:43 AM
  #21  
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Originally Posted by BlueRCF10 View Post
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....
So is SIA essentially a tuner and just changing shift parameters? Is this something RR Racing can do, or are they solely tuning engine parameters?
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Old 01-12-19, 07:01 AM
  #22  
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Originally Posted by BlueRCF10 View Post

The fact that my 2008 GS has this and my 2015 RCF also has it is ridiculous. Lexus shouldíve considered a fix for this since then...
Did the RCF not exhibit these symptoms when you test drove it or did you not take it for a long drive? Iím assuming not since you are seemingly quite familiar with it through your GS.
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Old 01-12-19, 09:19 AM
  #23  
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Originally Posted by Teutonic View Post
So is SIA essentially a tuner and just changing shift parameters? Is this something RR Racing can do, or are they solely tuning engine parameters?
Iím not really sure to be honest. They specialize in electronics and specifically ECM/ECUís etc....
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Old 01-12-19, 09:22 AM
  #24  
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Originally Posted by Limelight View Post


Did the RCF not exhibit these symptoms when you test drove it or did you not take it for a long drive? Iím assuming not since you are seemingly quite familiar with it through your GS.
Correct, I test drove it but it was on long country roads and I didnít have the chance to drive it in a more stop and go scenario. On top of that, I really didnít think this would still be a problem by now. After taking possession of it and once I hit the Toronto rush hour traffic chaos, thatís when I noticed it. Everything else is amazing on this car.
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Old 01-12-19, 09:40 AM
  #25  
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I have a 2017 RCF and have only had the car for about 3 months (bought used). I have noticed this same thing during normal auto mode coming down in speed around 20 mph (I am thinking 3 to 2 shift). It is not a strong jerky feeling, more like like the rear wheels are sort of dragging for an instant as the revs match. It is only at that shift.
I am glad to hear others mention so I know it is not my particular car. I did mention to my service manager when I got the oil changed and he didn't seem to know of anything about it (of course they didn't seem to know much of anything about the RCF - he had to look up how many quarts of oil it takes, etc.)

Love the car overall

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Old 01-12-19, 12:05 PM
  #26  
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Originally Posted by 3IS350Guy View Post
Oh I see - I guess in normal mode, the ECU is probably shifting at different (lower?) points than what i'm performing manually.

When I was testing the LC500, I noticed that they have this issue fixed. I shifted down from 2->1 at low speed with no lurch / jerk. I wish they could update our ECU with just this fix. Also, that other issue with the slight power cut out at around 2800-3000 RPM is really annoying when you're playing a smooth symphony with the exhaust.

Waiting for the LC F, but im probably going to jump into a MP4-12C by then.
yeah the LC500 has the new 10 speed trans. The new trans is way faster on upshifts and downshifts. There is hardly any jerk or lurch. Hopefully the new 10 speed trans makes it's way into the track edition but highly doubtful.
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