Engine shutter from speed changes while driving


#1

I’m not sure what is the correct term to describe the engine behavior. Maybe backfire, knocking, but it doesn’t sound like the youtube videos I see online. I just know that under certain conditions, the engine shutters with an exploding feel to it like it needed to “pass some gas” for a human.

This happens when braking quickly from high speed to slow speed or a quick stop. Also happens when accelerating then stopping a bit and resuming acceleration (an interrupted acceleration as rush hour traffic not allow for a nice acceleration - you know how people stop and go speeding up then having to break and repeat, affecting you and when you misgauge the best optimal acceleration speed, you have to stop acceleration a bit then resume).

I drive automatic transmission. Are many auto tranny cars affected by this type of thing? I seem to notice it with the cars I’ve driven. Or maybe I drive crappy cars, lol. I think I noticed it once in a friends manual shift car. This expected normal behavior of cars?

Car drives fine except for the mentioned behavior for the drastic speed changes.


#2

Car make, model year? mileage? relevant past maintenance on transmission?


#3

In addition to the points mentioned by BillRussell, the OP should tell us whether the Check Engine Light is lit-up.

Without any real clues at this point, one possibility that comes to mind is a dirty/malfunctioning MAF (Mass Airflow sensor), but that is just a WAG, and for all we know, this mystery vehicle might not have a MAF.

Of course, the other thing that comes to mind is that a problem with the “shutters” should lead one to also check the condition of the siding. :wink:


#4

It might not be the engine but instead the transmission lock up torque converter (LTC). If your car uses an LTC, and this problem tends to occur around 35-45 mph, either accelerating or slowing down, or even just going a steady speed, that’s where I be most suspicious. The problem is fairly common on newer cars with automatic transmissions & called “torque converter shudder”.


#5
Car drives fine except for the mentioned behavior for the drastic speed changes.

If your car has the new “dual-clutch” transmission (Ford Fiesta/Focus, Dodge Dart) this might be considered “normal.”


#6

Sorry, forgot to follow up. The car is a 2006 Suzuki Forenza, automatic transmission. Currently 80k miles. Original transmission still, that never been serviced except for transmission fluid replacement (perhaps not exactly to the schedule by time/miles, last replaced at 58k miles 3 yrs ago), and replacement of a malfunctioning transmission range switch sensor (5 yrs back @ 38k miles, engine code P0705). The switch sensor went senile and couldn’t figure out what gear you were in switching between gears erratically, when you shifted gears. I came across that briefly and managed to take it to the dealer to be fixed.