Very hard 4->5 upshift ONLY on 1st shift after starting car

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NEW!!!

I will make one calibration change for an additional $100 per change. For example, changing a shift point for a given gear is $100 vs changing a shift point and a pressure setting would be $200. That value can be used towards the full custom tuning price.

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Wed, 02/01/2017 - 06:08

#1

jtrosky

Very hard 4->5 upshift ONLY on 1st shift after starting car

I have a 2012 Impala (3.6L LFX engine and 6T70 trans) that I've "tuned" myself. I'm VERY much a novice and have tuned it just from learning from the HPTuners forums and from reviewing changes in a performane tune that I purchased for it (which I don't use). My goals for the car are "comfort-based" and not "performance-based". Mainly, I wanted to tune it becuase I hated the way that the 6T70 shifted.

Anyway, with the backround out of the way, here is my question/problem....

Generally speaking, the car shifts better than it did when I bought it. However, i've noticed that if I start the car and then accelerate to about 40mph right away and let off the gas (to make a turn, for example), the 4->5 shift around 40mph is VERY hard. it's only hard for the first 4->5 shift and only if it happens withing the first minute or so after starting the car. I've noticed that when I let off the gas in that situation to start slowing down, the RPM's don't drop - they kind of hang up there until I get the very hard shift. Normally, when letting off the gas in that situation, the RPM's drop down normally.

If I do the exact same thing without shutting off the car before doing it, the shfit is fine. And it doesn't seem to matter how long the car is shut off for - or how long I let it "warm up" before driving it.

I mainly notice this in one particular spot. I go to the pizza shop, shut the car off, go get my pickup order and then re-start the car. I pull out of the parking lot and get up to about 35mpg pretty quickly (to merge into traffic) - then, I have to make a left turn acorss traffic pretty quickly, so I let off of the gas to start to slow down - and that is where the RPM's seem to "hang" until I get that very hard shift. But again, only if I shut the car off. If I leave the car running when i go in to pickup my food, the hard shift does not happen in that same situation.

Any idea what might cause this? I honeslty don't know if it happened with the stock tune or not since I haven't had the stock tune on there in quite so time. I would be glad to share the stock and current version of my tune if that helps.

Thank you! Sorry for the long post, but I wanted to try and explaint the issue as best I could.

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Very hard 4->5 upshift ONLY on 1st shift after starting car

Click on the "SUBSCRIBE" tab to sign up. I will not respond to technical questions unless you are a paid subscriber. Calibration and Config files will not open directly from the site, they must be downloaded to your computer in order to open.

NEW!!!

I will make one calibration change for an additional $100 per change. For example, changing a shift point for a given gear is $100 vs changing a shift point and a pressure setting would be $200. That value can be used towards the full custom tuning price.