Jolting 2007 Buick LaCrosse

Ray, I have a real intermittent problem. From time to time, like once every two months or twice a week, the car will give a jolt as if the transmission just engaged or you “popped the clutch”…which is hard to do on an automatic, when you go forward from a dead stop or a real slow coast in traffic with frequent stops. This may happen after driving a mile or two or 20 miles or more but it definitely won’t happen if you are trying to make it happen. I can’t find anything with any regularity that makes the car jolt. After the jolt everything is fine as far as acceleration and shifting. The engine doesn’t rave up; the fuel does not seem to be starved the “CV” or equivalent has been checked and not slop. The car only has 114,300 on it so it’s still pretty new. I’ve checked the transmission fluid numerous times and the transmission has been serviced periodically as it should (that dip stick is really hard to read because it always has fluid on it no matter how you wipe or how careful you put it back in). Mechanics are stumped and of course can’t recreate the problem. This was my Dad’s car before he passed. Do you think it’s haunted? If it’s not, what’s your best guess?

If you are experiencing minimal to severe jerking over time, regardless of outside temperature, your throttle position sensor might be at fault.

If the PCM detects a problem with the transmission, the PCM will raise the line pressures within the transmission to prevent damage from slipping.

This will feel like a jolt because the higher line pressures cause the clutches within the transmission to grab faster to prevent slippage.

Take the vehicle to a shop and have a scanner plugged in to see if there are any pending codes regarding the transmission.


Wow! I’m impressed! Thank you! I was not expecting a personal reply. I called my mechanic and we are going do as you suggest on Thursday.

Thank you, thank you, thank you…glad to hear the car is not haunted after all.