Hi Scotty and others,
I drive a 1993 Lincoln Towncar, still rocking the old OBD1 system. It's a 4 speed automatic transmission with a little over 180,000 miles. With the help of yourself and others such as ChrisFix, I'm looking to start learning how to do repairs on my own. That said, my Check Engine Light has been on for a few weeks. Using the paperclip trick, I found it spat out an error code for a Coolant Temperature Sensor. I took it to a local mechanic, and he replaced the sensor after testing it and finding it to be "way out of range" (his words). However, the CEL has stayed on, and after acquiring an OBD1 scanner and performing both KOEO and KOER tests multiple times, I have not had it throw any codes other than 111 - No Fault Found. I have attempted to erase any saved codes by first disconnecting the battery, then by using a feature of the scan tool I recently purchased. Neither has stopped the light from coming on. Prior to this mechanic replacing the sensor, I did find that turning off the Overdrive and getting the car to speeds above 55mph caused the light to go off. Since the sensor has been replaced, this is no longer the case.
In all the tests, I have used the OBD1 scan port on the driver's side of the engine bay. My question, is it possible that there's another OBD1 port on the car that may provide different results? Are there any known causes of a Check Engine Light with no codes? Online reading has suggested that it may be emissions-related, so how might I go about doing more specific tests to narrow down the issue?
Another issue with the car - I have found no way to reproduce this so far, but twice now, I have had the transmission disengage completely while driving. I'd go over a bump, and suddenly my accelerator pedal wouldn't cause anything to happen with the engine. Coming to a stop, switching to Park, and back to Drive fixed it in both cases. I did find that the negative battery terminal was a bit loose, and tightened down the connector. The issue has not occurred since, but I figured I'd throw this information in as well.
The car is my daily driver, so I'm hoping to resolve any issues ASAP to avoid more expensive repairs.
Thanks for all you do Scotty!
-Iggy
The more I read the more and more I leaned toward transmission issues. A vehicle this old and some other things you mentioned tho makes me think there could be some other (small) issues too. I recommend finding a good mechanic in your area and asking them to give the car an overall inspection, not necessarily ask him to fix something initially, but so as you can get a good idea how much $ will be needed to get it back to it's nice self. Assuming you want to keep it of course.
