To_the_levee
New member
Hi all - 2012 Sonic LTZ 4 Cylinders H 1.8L Automatic, 108k miles. I recently had an oil change, replaced bad thermostat and radiator fan. The below symptoms have been occurring for 9+ months:
Poor gas mileage. Computer reads 24mpg even after highway driving.
Excess vibration, especially when idling at a light. Can feel / hear it throughout the car.
General engine noisiness / fussiness when accelerating, even at low speeds. Granted, this is no performance vehicle.
And the worst: intermittent but severe transmission? problem. I don’t actually know for sure whether this is the trans, but here’s what happens— every couple months, I’ll be driving and the car suddenly starts kicking violently and shifts unexpectedly. Hard to describe but it will literally “kick” so hard that it tosses me forward or backward in my seat. Dangerous to drive because speed changes drastically. So I’ll pull over, shut her down, and give her a few minutes to rest. The first time this happened I discovered the gas cap was loose. Tightened it and no more issues that day. It’s happened 2 more times since. The second time, nothing loose that I could find, and the car was fine when I turned it back on 5 min later. Most recent time, started acting up and even after turning off / starting up 3 times, still was kicking. I drove it straight to a nearby shop and cut the engine. The guys drove it around about 30 min later to inspect, and it ran smoothly. No codes or pending codes. It’s been about a week and no more issues other than maybe slight stickiness with shifting, but I also might just be paying more attention now.
I’ve had it in to 2 different shops and aside from the known issues listed at the top of this post, nobody has been able to find something that accounts for these symptoms. I’m trying to keep this thing running for another year ideally, so any help would be much appreciated.
Thanks
Poor gas mileage. Computer reads 24mpg even after highway driving.
Excess vibration, especially when idling at a light. Can feel / hear it throughout the car.
General engine noisiness / fussiness when accelerating, even at low speeds. Granted, this is no performance vehicle.
And the worst: intermittent but severe transmission? problem. I don’t actually know for sure whether this is the trans, but here’s what happens— every couple months, I’ll be driving and the car suddenly starts kicking violently and shifts unexpectedly. Hard to describe but it will literally “kick” so hard that it tosses me forward or backward in my seat. Dangerous to drive because speed changes drastically. So I’ll pull over, shut her down, and give her a few minutes to rest. The first time this happened I discovered the gas cap was loose. Tightened it and no more issues that day. It’s happened 2 more times since. The second time, nothing loose that I could find, and the car was fine when I turned it back on 5 min later. Most recent time, started acting up and even after turning off / starting up 3 times, still was kicking. I drove it straight to a nearby shop and cut the engine. The guys drove it around about 30 min later to inspect, and it ran smoothly. No codes or pending codes. It’s been about a week and no more issues other than maybe slight stickiness with shifting, but I also might just be paying more attention now.
I’ve had it in to 2 different shops and aside from the known issues listed at the top of this post, nobody has been able to find something that accounts for these symptoms. I’m trying to keep this thing running for another year ideally, so any help would be much appreciated.
Thanks
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