Hey, first time posting here, hoping you guys can help diagnose this problem I had today.

I was on my way home and drove around ~250km on the highway going 120-135 km/h the whole way. At that point I hit a patch with construction and the highway was at a stand still. Once the traffic moved a little I touched the gas and the car would jerk 1-3 times quickly then start rolling along. I also noticed white smoke coming from the hood. I was trying to press the gas as lightly as possible not to cause too much jerking and hoping the smoke would subside. Also I'm not sure but I think the car wasn't rolling when I let go of the brake but I'm not 100% on that.
This continued for ~10 minutes and luckily went away before I was out of the construction. After that I drove home perfectly fine going 100 km/h
This is a 04 TL with 161km on it. I just got the oil change done on a week ago with full synthetic.

 

Are you certain it was white smoke? Could it have been steam (i.e. water vapor). Did you detect any odor? Did the temperature gauge rise?

Regardless if it was smoke or steam, it was one of the vehicles fluids being over heated or dripping onto a hot surface that caused the "smoke". The liquid may have dripped (or been thrown by the fan) onto the spark plugs and/or coils causing a misfire and rough running engine.

It could have been oil that was being spewed from the filler hole because they forgot to replace the cap when you got the oil changed, or maybe they checked your antifreeze levels and overfilled the reservoir, or forgot to replace that cap.

You should be checking all fluid levels, and make sure that all caps and dipsticks are in place and properly tightened. (Motor oil, Power steering fluid, Transmission fluid, Brake fluid, radiator and overflow bottle).

 

I'll take a look at all the fluids and caps first thing in the morning. And yes, it could possibly have been steam, actually more likely as it was not very thick and would dissipate fairly quickly, it was blowing towards the back and would dissipate by the time it got close my side mirror. I only noticed it coming from the driver side of the hood since I didn't check the right side. There was a guy who rolled down his window and looked directly at the right side of my hood as he was driving by, not sure if that was because of the vapour/smoke or just a coincidence. I did drive 350-400km on Monday straight and there were no problems. It was approximately the same distance as today.

I was more worried about it being a transmission issue or an issue with me not having replaced the timing belt yet. Are any of those symptoms indicative of a tranny problem?

 

That description would lead me to think you need to look at your transmission fluid. Highway speeds, white smoke, and jerky engagement/movement....start there.

 

It may have been the transmission, if they had overfilled it during the oil change. That may have caused the jerkiness, and if the excces fluid was forced out of the dipstick tube, you would have seen smoke.

I'm more inclined to think they forgot to put the cap back on the rad. At highway speeds the air flow might have kept the rad cool but when you slowed down the antifreeze heated up and boiled over. This would have caused steam, and if the liquid touched your sparkplug wires (or coils on plugs if you have those) you would experience a misfire.