Chrysler Repair: Plymouth Breeze lurching, rattling, combustion chambers, plymouth breeze

Question
Dear Roland,

I have a 1999 Plymouth Breeze.  Lately, it has started to lurch forward when I'm
breaking at a stop sign or red light. My mechanic "ran codes" and couldn't find
anything wrong with it.  Also, it has started making a very loud rattling and
banging sound under the right hood for 30 seconds or so after I turn off the engine!
This happens even if I haven't been running the air conditioning.  Any thoughts?

Thanks.


Answer
Hi Donna,
I am quite surprised that these two behaviors has not set a code. If there is an Autozone parts store near you I would take it there and have the fault codes readout again, for free.
The lurching forward may indicate that the automatic transmission's lock up clutch on the torque converter is not releasing. Notice whether this happens or not when you have only driven the car at no more than 30 mph since the last stop and compare to when you come to a stop after having driven at least 40 mph since the last stop. That would be of possible diagnostic significance.
On the after shut off noise, that sounds like it might be 'dieseling' which can only happen if there is 'hot spot' in one of the combustion chambers due to carbon buildup, and that one of the fuel injectors is leaking fuel instead of shutting off. So I would check the spark plugs after shut down to see if any of them look "wet" with fuel.
It you get any fault code numbers (ask for the complete set of numbers which are 4-digits in length) let me know and we can go from there. Also, tell me which engine and transmission you have in the car.
Roland