I have an 85K Formula with auto trans. Recently, I've noticed that on cooler mornings, the car will idle down the road at 20 mph without pressing on the accelerator. The tach reads about 1500 to 1700 rpm. Possibly related, the TCC won't lock up until I've driven several miles. Once the car is warm, idle and TCC work fine. Any advice on where I should start?

quote Originally posted by YelloFormula: I have an 85K Formula with auto trans. Recently, I've noticed that on cooler mornings, the car will idle down the road at 20 mph without pressing on the accelerator. The tach reads about 1500 to 1700 rpm. Possibly related, the TCC won't lock up until I've driven several miles. Once the car is warm, idle and TCC work fine. Any advice on where I should start?

The engine must be in closed loop for the TCC to lockup. As far as the idle, are you getting any codes? Is it possible the tach is off? Vacumm leak?. If you are not getting any codes, I wouldn't worry about it.............Paul

Thanks, however the idle thing is new, makes driving in traffic a little unnerving. I'm not getting any codes. As far as the TCC, it sometimes doesn't lock up all the way to work (28 miles @70 mph). My gas mileage also seems low. I've owned the car for 7 years and something has definitely changed. Could this be a temp-related issue? something as simple as a thermostat (my temp gauge is unreliable, but seems to read much lower than in the past) or coolant temp sensor?

quote Originally posted by YelloFormula: Thanks, however the idle thing is new, makes driving in traffic a little unnerving. I'm not getting any codes. As far as the TCC, it sometimes doesn't lock up all the way to work (28 miles @70 mph). My gas mileage also seems low. I've owned the car for 7 years and something has definitely changed. Could this be a temp-related issue? something as simple as a thermostat (my temp gauge is unreliable, but seems to read much lower than in the past) or coolant temp sensor?

Yes, it could be a bad/stuck thermostat............Paul

If it were my car I would replace the E.C.M. coolant sensor that is screwed in the intake right above the waterpump.

Steve

quote Originally posted by YelloFormula: I have an 85K Formula with auto trans. Recently, I've noticed that on cooler mornings, the car will idle down the road at 20 mph without pressing on the accelerator. The tach reads about 1500 to 1700 rpm. Possibly related, the TCC won't lock up until I've driven several miles. Once the car is warm, idle and TCC work fine. Any advice on where I should start?

So your basically saying that since the wheather has gotten colder--your first start of the day cold idle has gone from 1500rpms on cold start up to 1700rpms ? This is normal--but you can check your mat sensor & cts sensor readings to make sure they are both working correctly.
http://winaldl.joby.se/

Replace your stat. If your not reaching 195 or taking a long time to get there your not getting into close loop and killing your gas mileage.
I've had that problem several times. It seems when the stats get old they float open and prevent the engine from reaching running temp.

This has been coming up more & more --get the 195 stock stat--you`ll save your-self some head-aches later down the road.