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Hitting rpm limiter on 1-2 solution?

 
Old 02-11-2019, 03:00 PM
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8850
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Default Hitting rpm limiter on 1-2 solution?

Aside from raising the rpm limiter or sending the TCM for unlocking can anything be done to stop my hitting the limiter on the 1-2 shift? Not sure how far to raise the limiter or how safe.

Would have ran a little better than my 10.36 had I gotten a clean 1-2 shift. Maybe quite a bit better, it really fell on it's face at shift? If you have HP Tuner you can see my log.
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Old 02-11-2019, 04:33 PM
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ronsc1985
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Are you using the shift lights in the HUD to tell you when to shift?. Using the linear tach automatically changes the rpm spread to redline vs the gear you are in, I.e. larger spread in lower gears since the engine is accelerating faster. If the 1st to 2nd spread is too narrow for your hand eye coordination I would assume you can change the spread in HP tuners.

This type of shift light operation is pretty standard for purpose built drag cars with electronic ignition boxes like high end MSD units. You can see this on TV when they show a Pro Stock driver going through the gears.
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Old 02-11-2019, 04:54 PM
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Originally Posted by ronsc1985 View Post
Are you using the shift lights in the HUD to tell you when to shift?. Using the linear tach automatically changes the rpm spread to redline vs the gear you are in, I.e. larger spread in lower gears since the engine is accelerating faster. If the 1st to 2nd spread is too narrow for your hand eye coordination I would assume you can change the spread in HP tuners.

This type of shift light operation is pretty standard for purpose built drag cars with electronic ignition boxes like high end MSD units. You can see this on TV when they show a Pro Stock driver going through the gears.
I am leaving the tranny in Drive with the factory shift settings. No manual shifting. Did not know the HUD had a shift light. The controls for shift light then must be in the TCM which I don't have unlocked.
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Old 02-11-2019, 08:15 PM
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almost impossible to get this right in manual mode with A8. i always leave in drive. shifts faster and my best ET is .2s quicker than in manual. if you need to hold in 4th longer in the 1/4, shift to manual near the end.
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Old 02-11-2019, 09:09 PM
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I watched a run on my pdr and noticed my car shifts 1 2 .. 2 3 almost 700rpm short. Car is bone stock.

Maybe you need to unlock it and command shift much earlier if modded?

My 3 4 shift is right at the mark. Weird.
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Old 02-11-2019, 09:48 PM
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I have had this happen as well. I manually shifted all last season at the drag strip just to avoid hitting the damn rev limiter. The 1-2 shift comes on really fast and there is no way that you can wait for the shift lights. As soon as I see 5800 rpm, I pull the paddle and it ends up shifting around 6200. I will be trying something this spring that might work? I think the car is going into "performance shift mode" since I put it into "M" while doing my burnout. It takes a little while for it to revert back to normal "drive" mode. Someone suggested holding down the right paddle for a few seconds after putting the car back into "D" after the burnout. The idea is this should force the car back into D. Makes perfect sense but I haven't been able to try it yet. The other option would be to do your burnout in "D" and see if that eliminates the performance shift mode and the 1-2 shift goes back to normal?

I have to admit, it is kinda fun manually shifting the car at the track. You are much more involved than just going for a ride. My PB is 10.09 at 138.5 with only a few bolt ons. Going for 9's this spring. Can't wait.
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Old 02-12-2019, 05:36 AM
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Thanks for all the input guys but I've decided to send it to HPT for unlocking. Other than the 1-2 I would like to adjust all shift points. The 3-4 and 4-5 are a little low. And I want to be able to change the throttle opening at launch. Was 36 mph on this log before opening fully.
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Old 02-12-2019, 08:06 AM
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Originally Posted by 8850 View Post
I am leaving the tranny in Drive with the factory shift settings. No manual shifting. Did not know the HUD had a shift light. The controls for shift light then must be in the TCM which I don't have unlocked.
There's your problem. You bought an auto. The auto has a pretty bad delay on shifting. You'll either have to just deal with the shift delay or trade the noob wagon in for a manual.

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Old 02-12-2019, 08:22 AM
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Originally Posted by Toddiesel View Post
There's your problem. You bought an auto. The auto has a pretty bad delay on shifting. You'll either have to just deal with the shift delay or trade the noob wagon in for a manual.
LOL! No manual tranny for me. I want to win drag races! With the programming fixed which I think is the only solution, I'll have a good 1-2 shift and improved 3-4 and 4-5
. My 137 mph and et will be even better.
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Old 02-12-2019, 08:27 AM
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Originally Posted by Toddiesel View Post
There's your problem. You bought an auto. The auto has a pretty bad delay on shifting. You'll either have to just deal with the shift delay or trade the noob wagon in for a manual.
I've driven manuals a good portion of my 70 years, but decided to go with the A8 this time around. I have yet to "blow" a shift with my A8, and enjoy hearing people with manual transmissions say they would have beat me had they not missed a gear.

Last edited by DevilDog II; 02-12-2019 at 08:28 AM.
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Old 02-12-2019, 10:38 AM
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If you goal is drag racing an auto is the way to go.
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Old 02-12-2019, 10:51 AM
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Originally Posted by 8850 View Post
Thanks for all the input guys but I've decided to send it to HPT for unlocking. Other than the 1-2 I would like to adjust all shift points. The 3-4 and 4-5 are a little low. And I want to be able to change the throttle opening at launch. Was 36 mph on this log before opening fully.
Not a drag strip guy. I believe the 36 mph before throttle opens fully is to help keep the tires from breaking free & TC kicking in which would actually slow your time. You might not like having to “manually” feather the gas instead of just keeping the gas pedal floored.JMO
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Old 02-12-2019, 11:19 AM
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Originally Posted by 8850 View Post
Aside from raising the rpm limiter or sending the TCM for unlocking can anything be done to stop my hitting the limiter on the 1-2 shift? Not sure how far to raise the limiter or how safe.

Would have ran a little better than my 10.36 had I gotten a clean 1-2 shift. Maybe quite a bit better, it really fell on it's face at shift? If you have HP Tuner you can see my log.
http://www.corvettes-of-westchester.com/contactus.html

Give Chuck a call and discuss your goals.
He might be able to help.
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Old 02-12-2019, 12:18 PM
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Originally Posted by Toddiesel View Post
There's your problem. You bought an auto. The auto has a pretty bad delay on shifting. You'll either have to just deal with the shift delay or trade the noob wagon in for a manual.
Have you driven an auto down the 1320?
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Old 02-12-2019, 12:43 PM
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Originally Posted by dar02081961 View Post
http://www.corvettes-of-westchester.com/contactus.html

Give Chuck a call and discuss your goals.
He might be able to help.
It's already on the way back to HP Tuners. I'll tune the tranny myself. Thanks though!
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Old 02-12-2019, 08:34 PM
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what's on its way back to HP tuners? i have their software but was not aware they offered services for corvette customers.
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Old 02-12-2019, 08:47 PM
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Originally Posted by CONMAX View Post
what's on its way back to HP tuners? i have their software but was not aware they offered services for corvette customers.
Having my TCM unlocked so I can make changes to my tranny tune. If you want to make changes to the tranny of 2017 and newer it has to be unlocked.
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