Automatic fights to up-shift and lug the motor

[baq]

2013 Sonic LT 4D 1.6L AT
Since I bought this car the automatic transmission has always wanted to upshift and it's a complete dog because of it. After I've turned a corner, it doesn't want to downshift and barely moves, lugging the motor leaving the corner. I have to almost floor the gas pedal to make it downshift and then it races. Similarly, when it encounters an incline, it remains in a high gear, slows, and the pedal has to be almost floored to get it to downshift. Further into the incline as it settles into a good cruise, the car upshifts slowing the car again, requiring that I floor it again and race. The result on a long incline is that I'm continually fighting the car, slowing and racing. It's ridiculous.

I've repeatedly been told to put it in manual to control it and of course I do. But here's the problem: I bought an automatic. Every one I've driven for 45 years senses resistance encountered and downshifted with only slight downward movement of the accelerator or even none at all – downshifting by sensing resistance or rpms vs speed alone. There is something with the computer or a sensor that prevents this car from reacting and I'd really like to figure out what it is. It's a great car otherwise, but this makes it an absolute loser.

The dealership was never any help. I'm in Colombia and once you've bought a car here they have little interest in service let alone warranty. So I'm on my own, but if someone can help troubleshoot this thing, there are some innovative mechanics here that may be able to apply some good advice. I'm optimistic as I've discovered some discussions helpful in other threads and can see the value of forums like this. Thanks

 

[jyahknots]

Sorry to be of little help, but I can help by saying that I deal with the same issues in my 2015 with the 1.4 liter engine. And I get the same exact answer from both dealerships I've taken the car too: "It's normal and we can't find any codes and/or reproduce the customers complaint." My Sonic is terrible at downshifting when slowing down--very rough downshifts and has a tendency to make you feel like it's bogging down quickly--but I think through reading and learning on my own, it's partly to blame on the "injector cutoff" that engages when you let off the gas and slow down. It's suppose to aid the engine/vehicle in slowing down by cutting off fuel to the fuel injectors, but if you were to touch the gas pedal again OR I think if the a/c compressor kicks on, the engine sense a load and turns the injectors back on and it causes a noticeable movement in the drivetrain....which feels like a bogging or more of a mimicking of an "extra downshift" sensation. I wish it could be turned off (the injector cutoff) for diagnostic purposes just so I could see if I'm right.

And I deal with the transmission hanging up in a lower gear when it should be in a higher gear at low speeds. When I drive about 30mph in the community I live in, I can hear the engine revving pretty high (upwards around 2100-2300 rpm's) and I feel it should be revving lower. ONCE IN A WHILE It'll downshift and act normal....but that's hardly ever. And it doesn't matter if the engine is cold or at normal operating temperature. And I REFUSE, just like you, to drive my car in "manual mode" when I got the car with an AUTOMATIC transmission. Stupid feature that is useless in a vehicle....unless you own a sports car, and a Sonic is FAR from that!! Haha

But yeah, I hope you and I and whoever else is experiencing this issue can get a solid answer from someone! Kind of wish I never got this car :-/

 

[spacedout]

Transmissions these days are programmed for MPG first and foremost, so will always try to get into the highest gear possible. Having more gears to choose from also means quite often its not in the perfect gear for every situation.

When turning a corner I always put the car in manual more and use 3rd of 2nd gear depending on how slow I'm going. Hills I find the automatic here is awesome, I believe they use the stability control yaw sensor to sense when your on the incline so it will hold lower gears even at light throttle input until the road levels out. If it downshifts, it will similarly hold that gear until the road levels out no matter how light you are on the throttle. Unlike some of the dumb automatics I've driven in the past that would shift back to high gear as soon as the road even somewhat leveled out or my cruise control set speed was met again.

By the sounds of things your letting your car hunt for gears on hills(downshift and upshift again), this is when you really should be using manual mode to lock the lower appropriate gear. Letting the transmission hunt between gears build a ton of heat and can shorten the transmission life. How many gars did your last car have? Does your sonic have a similar 6 speed auto as the US model?

 

[spacedout]

And I deal with the transmission hanging up in a lower gear when it should be in a higher gear at low speeds. When I drive about 30mph in the community I live in, I can hear the engine revving pretty high (upwards around 2100-2300 rpm's) and I feel it should be revving lower.

I suspect the area you are driving is slightly inclined is why are experiencing this, the transmission is being smarter than you are(No offence intended). Sure you could be in 5th gear but you would only be running 1500RPM, remember the turbo engine doesn't make much power until beyond 1850RPM. Running low RPM and high load can cause knock and damage the engine. What grade fuel you running? 87 octane ride the knock sensor in this RPM range pretty heavily and makes this seem worse, running high octane does give better low RPM power(before boost) and protect against that knock occurring. I find my car more readily to use 5th in the same situation when running 93 octane.

And I REFUSE, just like you, to drive my car in "manual mode" when I got the car with an AUTOMATIC transmission. Stupid feature that is useless in a vehicle....unless you own a sports car, and a Sonic is FAR from that!! Haha

This isn't the old 3 or 4 speed automatics that could use 2nd gear to 75mph, there is many situations manual mode is great when you have so many gears to choose from.

I live in a very hilly area and quite often lock out 6th gear and just use 5th for hours on the highway. Stop and go traffic jams(real city driving) I will lock 2nd or 3rd gear so as traffic goes from 0mph to 30 mph and back to 0mph every 500ft as traffic speeds up and slows down, this keeps the transmission from shifting 1-5 and back to 1st gear continually.

 

[jyahknots]

My community is completely flat. Here in Florida, we don't have much for hills....if any at all. I run 93 octane, and have since I got my Sonic back in June of last year. And I've tried using manual mode before in the situation I described in my community; and it wouldn't let me shift into a higher gear to slow the engine down and not sound as if I was driving an actual manual transmission and was to lazy to shift into the next higher gear.

Not sure if I mentioned in my past above, but through reading I've learned about the "fuel injector cutoff" that's incorporated into our ecm to conserve on fuel. I think that's why I feel "so many downshifts" when I'm slowing down.

 

[spacedout]

I've tried using manual mode before in the situation I described in my community; and it wouldn't let me shift into a higher gear to slow the engine down and not sound as if I was driving an actual manual transmission and was to lazy to shift into the next higher gear.

Even in manual mode there are shift points, the MPH you need to be going to be allowed to shift into the next gear. If you going slower than those speeds it will not let you shift no matter how many times you press the button. My guess if you are going say 25mph you were in 4th gear, with my 2015 LTZ 1.4T automatic you have to be going 29MPH to shift in to 5th gear. In automatic mode there are times like with the AC on it will hold the gear out above that speed a bit, but with flat roads and a light foot should be in 5th running quietly at anything above 30-32mph.

In 25mph zones, I typically set my cruise control at 29-30mph just to get the automatic to shift into 5th gear, no manual mode required. Try it, I would love to hear if that helps!