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Old 03-17-2012, 05:03 PM   #1
E.T.


 
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L99 changing gears

Just wondering if this has happened to anyone else? I experienced this a few times, maybe around 40-ish mph. I was merging onto the freeway behind one of those slow pokes, so I give it some gas and change lanes to pass and it was like the car wasn't sure which gear it wanted to be in. It was like it went back and forth a few times. If I recall, I didn't have the pedal all the way down.

Another time, I was making a left and accelerated fairly hard, but didn't have the pedal all the way down. I'm thinking maybe it downshifted, but then I started letting up on the pedal and it upshifted, so then I gave it more gas and it downshifted again. All I can think of is that I was at just the right speed between 2 gears and it somehow got confused. Not sure if I'm explaining this clearly Anyway, cruising is fine and highway driving is fine, it's just these couple of times right around 40. BTW, this was in "S" mode.
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Old 03-17-2012, 05:32 PM   #2
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Originally Posted by E.T. View Post
Just wondering if this has happened to anyone else? I experienced this a few times, maybe around 40-ish mph. I was merging onto the freeway behind one of those slow pokes, so I give it some gas and change lanes to pass and it was like the car wasn't sure which gear it wanted to be in. It was like it went back and forth a few times. If I recall, I didn't have the pedal all the way down.

Another time, I was making a left and accelerated fairly hard, but didn't have the pedal all the way down. I'm thinking maybe it downshifted, but then I started letting up on the pedal and it upshifted, so then I gave it more gas and it downshifted again. All I can think of is that I was at just the right speed between 2 gears and it somehow got confused. Not sure if I'm explaining this clearly Anyway, cruising is fine and highway driving is fine, it's just these couple of times right around 40. BTW, this was in "S" mode.
All the auto tranny cars I've ever driven have a spot where they hunt gears. I suspect nothing much wrong. Kinda the way it is. Of course if that happens with mine (6MT) - I know why - I goofed
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Old 03-17-2012, 07:24 PM   #3
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Thanks, yeah, hunting is a good description of what it seemed to be doing.

Is it possible the trans was still adjusting to my driving? I've read these have adaptive learning. I loaded a new tune a few days ago, so I'm not sure how long it takes to go through the "learning" process.
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Old 03-18-2012, 12:53 AM   #4
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I had my L99's trans tuned and the power shifting with the decreased torque management seemed to be causing the "gear hunting" when doing dramatic downshifts. Started happening a fair bit, seemed to be mostly on 4>3 or 3>2 downshifts.

It was sporadic and never seemed to happen exactly the same. Sometimes the exact same scenario of shifting wouldn't cause the problem, other times it'd be harsh, and other times not as bad. I was racking my brain and looking at my tune and such until it happened again and I realized what the issue was.

I realized that the power shift would throw me back in the seat so much that it would pull my foot off the pedal just a bit, so I'd be going from WOT down to about 75%, then back to WOt, and sometimes, back down to 70-80% again. The shift points are based off your Throttle position and your current speed, so changing the throttle position meant chaos on the shift point tables. The car was simply doing what it was told! I moved my seat up a bit and I haven't had the problem since.
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Old 03-18-2012, 01:20 AM   #5
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Originally Posted by AiRDawG View Post
I had my L99's trans tuned and the power shifting with the decreased torque management seemed to be causing the "gear hunting" when doing dramatic downshifts. Started happening a fair bit, seemed to be mostly on 4>3 or 3>2 downshifts.

It was sporadic and never seemed to happen exactly the same. Sometimes the exact same scenario of shifting wouldn't cause the problem, other times it'd be harsh, and other times not as bad. I was racking my brain and looking at my tune and such until it happened again and I realized what the issue was.

I realized that the power shift would throw me back in the seat so much that it would pull my foot off the pedal just a bit, so I'd be going from WOT down to about 75%, then back to WOt, and sometimes, back down to 70-80% again. The shift points are based off your Throttle position and your current speed, so changing the throttle position meant chaos on the shift point tables. The car was simply doing what it was told! I moved my seat up a bit and I haven't had the problem since.
That's a possibility. Today when it happened, I was turning left and I gave it a decent amount of throttle through the corner, but I didn't want to go too crazy, so I let up a bit, and then gave it some more gas again. It could be that I was at just the right speed & throttle position to be at the tipping point for shifting.
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Old 03-18-2012, 07:59 AM   #6
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HP Tuners has some new parameters that is supposed to help with the hard downshifts at cruisin speed where the car cannot decide if it wants to do 1 gear change or up to 4 gear (6-2) changes.
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Old 03-18-2012, 08:16 AM   #7
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What you're discribing is very common.
That's why I nail the gas pedal to the floor if I want the transmission to drop all the way down (say drop to 2nd gear cruising 45 - 50 mph).

When you go part throttle, the computer is trying to read your throttle position and put the transmission in the correct gear. That can sometimes cause hesitation or momentary confusion when switching gears.
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Old 03-18-2012, 11:19 AM   #8
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How many miles do you have on your car? I have been told that these trans, more specifically, the trans computer is a learning computer and that they need a decent amount of driving before they "Learn" how to drive. Not sure there is much to this but I can see it.

I have never had much trouble with mine as I am running a JRE trans tune and its sharp and decisive with its shift points. Have never had any "hunting" for gear situations.

I have had a few times when driving in S mode with the factory tune that the car would hold gears longer then expected keeping rpms up after a high rpm dash such as passing another car. Was told this was normal as the S mode will hold the rpms up longer so that the car does not shift as much in a road course type of driving situation where you may want to let off the trottle but not shift to a higher gear ratio so that you keep your engine in its power band more consistantly.

If I were you, I would get a good trans tune and I would recommend Ted and his crew at JRE. Turns the car into a totally different animal. You will not believe the difference it makes with just a good engine and trans tune. If you do not want to worry about the warrantee issues and keep the stock tune, I would say its just something you will have to deal with but it should reduce with time as you drive your car more and more. If your worried, of course take it to your dealer for a quick check over of the trans for piece of mind. You have a bumper to bumper warrantee, use it if you have ANY issues or worries about you new car, thats what it s there for.
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Old 03-18-2012, 11:27 AM   #9
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You could use the paddles too. That would lock it to what ever gear you like till you want to go back to cruising.
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Old 03-18-2012, 12:39 PM   #10
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Quote:
Originally Posted by SGOS252382 View Post
What you're discribing is very common.
That's why I nail the gas pedal to the floor if I want the transmission to drop all the way down (say drop to 2nd gear cruising 45 - 50 mph).

When you go part throttle, the computer is trying to read your throttle position and put the transmission in the correct gear. That can sometimes cause hesitation or momentary confusion when switching gears.
I will keep that in mind. That's pretty much what the manual says, too...."If more power is needed for passing, and vehicle is going less than 35 mph, push accelerator halfway down, and if about 35 mph or more, push the accelerator all the way down."

The time it happened on the freeway, I remember not stepping on it all the way. I wanted to get around the slow guy, but I didn't want to go balls to the wall and blow his doors off, so I probably went maybe 75% throttle.

Quote:
Originally Posted by Fiftydriver View Post
How many miles do you have on your car? I have been told that these trans, more specifically, the trans computer is a learning computer and that they need a decent amount of driving before they "Learn" how to drive. Not sure there is much to this but I can see it.

I have never had much trouble with mine as I am running a JRE trans tune and its sharp and decisive with its shift points. Have never had any "hunting" for gear situations.

I have had a few times when driving in S mode with the factory tune that the car would hold gears longer then expected keeping rpms up after a high rpm dash such as passing another car. Was told this was normal as the S mode will hold the rpms up longer so that the car does not shift as much in a road course type of driving situation where you may want to let off the trottle but not shift to a higher gear ratio so that you keep your engine in its power band more consistantly.

If I were you, I would get a good trans tune and I would recommend Ted and his crew at JRE. Turns the car into a totally different animal. You will not believe the difference it makes with just a good engine and trans tune. If you do not want to worry about the warrantee issues and keep the stock tune, I would say its just something you will have to deal with but it should reduce with time as you drive your car more and more. If your worried, of course take it to your dealer for a quick check over of the trans for piece of mind. You have a bumper to bumper warrantee, use it if you have ANY issues or worries about you new car, thats what it s there for.
I have about 850 miles on her, but I just put a new tune on several days ago, so I'm thinking the tranny has to relearn all over again. Not sure how long that takes?

BTW, I do have the JRE tune, and it's awesome I'll ask him about it if I keep encountering this issue, but at this point, I think it's just about my foot learning how the car responds to different throttle positions.
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Old 03-18-2012, 03:15 PM   #11
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Yes it will relearn but it does not take all that long, I have heard several cycles through the gears is pretty much all it takes.

If you have any issues, get ahold of Ted, he will solve any issues or at least educate you as to what you seeing with the car. He has always been a HUGE source of education for me with my L99.

Really invaluable to us guys that do not live within range of a good performance shop.
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Old 03-19-2012, 09:32 PM   #12
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L99 4-2 shift advice

Quote:
Originally Posted by Fiftydriver View Post
Yes it will relearn but it does not take all that long, I have heard several cycles through the gears is pretty much all it takes.

If you have any issues, get ahold of Ted, he will solve any issues or at least educate you as to what you seeing with the car. He has always been a HUGE source of education for me with my L99.

Really invaluable to us guys that do not live within range of a good performance shop.
I find myself quite often cruiisng onto an on ramp in tapshift 4th gear
(s mode) then to merge I quickly double tap down to 2nd to get a quick burst of power,rpm's shoot up fast as you can imagine, then I slowly tap back up to 4th. Can anyone advise if the double tap from 4-2 is a bad idea-could it eventually cause problems to the computer?
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Old 03-20-2012, 06:00 PM   #13
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This happens to me too, seems like the computer thinks your stepping on it but is not sure. When I drive in M, I dont get that problem.
Now, you guys with tune, while driving in M and lets say your at 45 mph on 4th gear and coming to a stop slowly. Do you guys manually shift down or let the computer shift you down? If you do manually shift down do you guys feel your car jerk kinda like trying to stop, hard to explain. I know when I had my stock down it wouldnt do that but I could also hear my exhaust rev back down, which I miss hearing that. I dont hear that anymore with the tune while down shifting.
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Old 03-20-2012, 07:35 PM   #14
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Happened again today. I keep getting stuck behind people on on-ramps who insist on merging at 45 mph. So I give it gas to change lanes and merge, and it seemed like it downshifted, upshifted, downshifted a few times. I must be right at the magic speed and throttle position at a shift point, and it's not sure what to do. As soon as it started to do this, I pushed the pedal all the way down, and the car stayed in the lower gear. I emailed Ted at JRE and he said this is normal. It's odd that this never happened before the tune, but then again, maybe the circumstances weren't the same. I never got much of a feeling for the car in its stock form, as I started doing mods right away, and got the tune around 250 or 300 miles.

Erk5000, mine seems to slow down normally. It doesn't seem jerky, but I usually just let the computer downshift. If you tap shift down, maybe it has to do with when you're downshifting (RPMs and vehicle speed).
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Old 03-20-2012, 07:56 PM   #15
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I have a TCM tune too and I noticed that it shifts prematuraly sometimes or that it's "hunting" for gears. I've also noticed that sometimes it shifts really hard, when it shouldn't or when I'm WOT, it will not shift hard at all.

I've also noticed that when it's downshifting that the 3-2 shift generally hits really hard almost like it went 3-1-2.

Could be my imagination.
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Old 03-20-2012, 08:30 PM   #16
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I have a TCM tune too and I noticed that it shifts prematuraly sometimes or that it's "hunting" for gears. I've also noticed that sometimes it shifts really hard, when it shouldn't or when I'm WOT, it will not shift hard at all.

I've also noticed that when it's downshifting that the 3-2 shift generally hits really hard almost like it went 3-1-2.

Could be my imagination.
Did it do that before the tune? Where'd you get your tune?
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