500 RPM Rev drop @ 2,500 to 3K in 2nd & 3rd IS350
08-01-07, 11:29 AM
#16
Pole Position
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My car's done that ever since I got it. I only notice it in the mornings when the car is cold, but that could be that its a characteristic of the car when its cold, or could just be that I pay more attention to my tach when the engine is still cold.
08-01-07, 02:55 PM
#17
Pole Position
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It sounds normal. Like the torque converter going in and out of lock. Your description of when and how it happens leaves out a lot of detail. Does it only happen during cold cycle? The transmission is restricted when it is cold to fourth gear maximum, then fifth gear until the ATF get sufficiently hot.
Does it only do it on very light throttle? There is a fuel cut at 2500 rpm if you lift your foot off the throttle.
Does it do it going downhill/uphill? The ECM is situationally aware and will engine brake going downhill and make other compensation based on whether you are climbing or descending.
Got any particulars about this?
Does it only do it on very light throttle? There is a fuel cut at 2500 rpm if you lift your foot off the throttle.
Does it do it going downhill/uphill? The ECM is situationally aware and will engine brake going downhill and make other compensation based on whether you are climbing or descending.
Got any particulars about this?
It happens during all cycles, not just cold cycle. Only happens in 2nd and 3rd. Only does it on light throttle, like you would do trying to maintain speed on a flat road. ECU can be in the neutral position or PWR position. A tech road with me and noticed it right away. So to recap, I am driving along in S mode which at any speed over 35ish will default to 4th gear, I then manually select 2nd or 3rd gear, the car shifts to 2nd or RPMs reach about 3k then with just a bit of throttle trying to hold at speed RPMs will drop about 500. I can replicate over and over just by going up to about 3k and repeating. It can be a pain when trying to drive smoothly i.e. with passengers around town. If car is left in D there is no problem at all.
I picked it up from the dealer today and they said they drove two other new 350's from the lot and noticed the same problem. They said there was no official TSB on it yet but if enough people had the problem Lexus may issue one. Also, while driving a ES350 loaner from the dealer for two days I could not duplicate the problem so I think it is only an issue with IS350's.
08-01-07, 06:57 PM
#18
Lexus Test Driver
I picked it up from the dealer today and they said they drove two other new 350's from the lot and noticed the same problem. They said there was no official TSB on it yet but if enough people had the problem Lexus may issue one. Also, while driving a ES350 loaner from the dealer for two days I could not duplicate the problem so I think it is only an issue with IS350's.
08-01-07, 07:13 PM
#19
Lead Lap
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How did you find this out, btw? Do you program ECUs for TMC/denso/whoever? Or are you just crazy like that?
08-01-07, 07:41 PM
#20
Tech Info Resource
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Just crazy like that. I learned a long time ago to read the documentation and learn about stuff before doing anything stupid. It's in the FSM...I was researching another project (I hope to make some progress on it soon) and came across this info. I've also known all the OEMs have a closed throttle fuel cut between 1800 and 1300 rpm for emissions controls since 1988. This is just an extension of that concept.
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