# Bucking while sitting at a stop



## AuditorBill (Jan 6, 2017)

I put 93 octane in all summer and this is my first tank of 89.

Twice in the past couple days, after starting the car, driving less than a mile, and coming to a stop light, the car doesn't shut off but bucks as if someone is pushing it in a staccato fashion from the rear. No CEL (of course).

Anybody else deal with this? Outside temp was mid-40's F. both times.

Wonder if the ECM is adjusting to the 89 octane and/or being so near the 41 degrees F. that the stop/start feature is designed to not engage at?


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## HatchLifeRS (Oct 3, 2017)

I can't explain the bucking feeling. Just guess that rpms are a bit higher since the car hasn't warmed up yet and is giving you that feeling.

As for the auto start/stop not working. I know with the gas engine it will disable bellow 40F/5Cish. Or maybe it's around 8C/46F I honestly can't remember. The temperature outside that the car is reading could be to cold and therefore it's disengaged.

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## NewCarBuyer (May 13, 2017)

Same thing is happening to mine. I had the car about 6 weeks now. Its a 2018 Cruze LS with 1100 miles. Mine does it within the first few miles of a cold start and only does it at a stop light. Once the engine is up to normal temp, the car will idle smoothly.


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## AuditorBill (Jan 6, 2017)

I had a check engine light for the first time a month or two ago. The code was for oxygen sensor. The service writer, whom I know and like, said the first fix is to reprogram the ECM. The car never did this bucking before. I wonder if this is related to the latest version of the ECM update. It's always amazing to me how stuff like this gets noticed out in the real world but not on the test track. Like you, this only happens at the first red light after I start the car.

All that said, I like my Cruze. Huge back seat; better-finished interior than other cars I think (chrome, and cloth on instrument panel); built in NE OH just down the road from me. I wish they would move production of the hatch from Mexico to Lordstown.


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## jblackburn (Apr 14, 2012)

Pop it in neutral and see if it still does it. I've felt this on random occasions. 

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