Rough/low idle

[1lslincoln]

2005 Lincoln Ls Sport. So recently I replaced my locked up motor (spun a bearing) and since iv started consistently driving she’s developed a lurch/shake. It only happens when idling or really slow speed (5mph and below). There’s no codes pertaining to a misfire, only code is for the downstream 02 sensor as I dont have cats. would this cause it? Iv checked just about everything i can think of to no avail (vacuum, coils, motor mounts, etc). Also more iv thought of after the fact, my fuel mileage is pretty bad, about 13mpg on a good day of city driving not beating on it. from what iv read this is pretty low but I have no other CEL besides downstream 02.

 

[MarkEricRoth]

If you find the speed that the shake goes away is increasing, check the fasteners that hold the engine and transmission together, they may be backing out. We had these same symptoms with a Dodge Shadow right after an engine swap. Turned out the garage forgot to torque the engine to the transmission.

 

[Buckie]

2005 Lincoln Ls Sport. So recently I replaced my locked up motor (spun a bearing) and since iv started consistently driving she’s developed a lurch/shake. It only happens when idling or really slow speed (5mph and below). There’s no codes pertaining to a misfire, only code is for the downstream 02 sensor as I dont have cats. would this cause it? Iv checked just about everything i can think of to no avail (vacuum, coils, motor mounts, etc). Also more iv thought of after the fact, my fuel mileage is pretty bad, about 13mpg on a good day of city driving not beating on it. from what iv read this is pretty low but I have no other CEL besides downstream 02.

Yes a unhooked O2 sensor can cause this since its not relaying back correct info for the computer to make proper Air/Fuel trim adjustments. First i would try clearing the code and then completely reset your computer by unhooking the battery for 30 mins and see if it runs better before the code comes back if so that 02 sensor could be you're problem. I would also make sure my intake and air inlet tube was tightened and torqued down properly and check them for air leaks. If either is letting unmetered air in after the MAP sensor it can cause the same problems without setting a code. The computer cannot properly adjust the fuel/air trims because it doesn't recognize how much air thats entering through the leak. To eliminate that downstream O2 sensor code you can always drill a hole in the exhaust pipe where the sensor is supposed to be, weld a nut and hook up a 02 sensor straight into the pipe and it should clear up that code.