Q: I just had the transmission replaced on my 2011 Nissan Juke with 56000 miles on it and now it is idling rough intermittently and t

Rough idle is typically fuel and/or ignition system related assuming that there are no mechanical problems with an engine such as uneven or low cylinder compression. The problem is diagnosed, in part, using a real time scanner which reports a wide range of engine operating parameters. Parameters that are out of range will provide the clues as to what is going on. Possible causes of rough idle are vacuum leaks (including EGR system faults), air induction faults such as a stuck idle air control valve, a faulty throttle position sensor, problems with the mass air flow sensor, defective spark plugs, a weak coil(s), defective oxygen sensor(s) and quite a few other possibilities including faulty fuel injectors. High RPM’s but less than expected vehicle speed may indicate a problem with the transmission shifting (which shifting problems, in turn, can potentially be caused by a defective throttle position sensor). If you desire that the problems you are having be diagnosed by a certified Mechanic, dispatched by YourMechanic right to your location, please request a rough idle diagnostic and the responding certified mechanic will get this resolved for you. If you have further questions or concerns, do not hesitate to re-contact YourMechanic as we are always here to help you.