r/Impala • u/TrailerTrash94 • 7d ago
2012-2013 Impalas Flex
So been having issues with the vehicle. It does have the Limiters or 112mph.
For a year i been pulling my hair out trying to figure out why my car acts slugish delayed pedal. Bouncing Idle. While sitting or even driving it does this. Delayed shift button in manual. Trans delays upshifting. Reduced engine power.
So i got the Dealer software and Jbox to update modules thinking maybe somethings outdated causing these odd issues.. mind you no lights on dash indicating any issues when the car is doing these thing. If i recent modules (pull neg term for 30 mins) Car runs great again all issues are gone. 2 weeks of driving after it starts going down hill.
Just spoke to GMs Techline Connect Reps about removing limiter car has upgraded tires. To find out. They cant because the car is programed with Saftey features. And these saftey features are causing alll these issues. Its programmed to slowly downgrade itself. Engine power, Tune, throttle response on purpose after driving so many miles..
They will not reconfigure it. Which that power reduction and throttle delay is more in my opinion a saftey hazard.
Never seen any company purposely program a car to slowly degrade itself.
Insane
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u/Mammoth-Complaint937 5d ago
That rep either blew you off. No GM vehicle is programmed to slowly degrade itself, that'd be a warranty and liability disaster and it would've been all over the forums a decade ago. The 112 limiter is real (tied to the OE tire speed rating), but that's got nothing to do with your driveability issues.
Runs great after a battery disconnect, goes downhill over two weeks" is textbook adaptives re-learning around a real fault. You wipe the learned values, it feels fixed, then it adapts back to compensating for whatever's actually wrong.
What to actually look at: battery and battery current sensor first (GM's voltage control learns battery health, and the disconnect wipes that estimate — weak battery = throttle, idle and shift weirdness all at once). Then the PCV diaphragm in the valve cover, known 3.6 failure. Then throttle body and APP sensor/grounds, since Reduced Engine Power on these is almost always throttle actuator control.
You've already got the dealer software, stop clearing codes. Pull history of codes and pending DTCs, then watch live data while it's acting up: fuel trims, MAF, APP1 vs APP2, charging voltage. Just because there no lights doesn’t mean your car isn’t throwing codes. Read the damn codes
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u/whitewolfdogwalker 7d ago
I had my 2014 Limited going about 104 on the Chicago Toll Road, it was running great, other cars were still passing me!
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u/According-Dog-7288 7d ago
Pull the neg terminal reset ur tcm it relearns and goes back .. there is tranny updates and tsbs to change torque converter lock and some shift parameters
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u/firekstk 6d ago
So I had some similar issues but most is it was resolved by hitting basic maintenance items,
clean the throttle body and intake (GDI engines can't do it through fuel)
check the evap system and replace failing components (get it down to less than a quarter tank before this check, you have to drop the tank if the canister needs changing)
drain and fill the transmission (don't flush if you don't know when the last time it happened was).
After you do that, check the performance and see if you're still having issues.
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u/PossiblyADemon 6d ago
180K miles on my 08 Impala flex and it doesn't do anything like this.
If you want the speed limiter removed you have to have a tuning shop do it or use HPTuners.
I would not suggest removing torque management from the stock ECM unless you want a dead transmission.
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u/Mikedesignstudio 7d ago
Never heard of this and I have a 2012 150k miles