99 Cavalier needs help (shucking action & temp. gauge stuck on cold)

[cass_17_7]

Here is what is going on: in the summer if I used my air condition sometimes my car would start jerking or shucking while driving and at the same time the temperature gauge needle would move back and forth and then just rest on the cold side. Well yesterday I got back from an 800 mile trip and about 300 miles into it my car started the jerking motion and the temp gauge was possessed again by moving from cold to the middle of the gauge. We got to the destination and let my car rest overnight and yesterday we had to leave for home again. Well it didn't start to jerk until an hour into the drive home, but the temperature gauge didn't raise. It was below cold. After awhile the car stopped jerking and drove fine, but then gauge was still below Cold. Then about an hour away from home my check engine light came on. We checked the oil, transmission fluid, antifreeze, and all that jazz but it was ok. So I am thinking it has something to do with the jerking and the gauge. My car only jerks and shucks at the same time as the gauge is going crazy. I started my car this morning and the check engine light is off now. Can anybody help me out with this?

[fst100]

if you still have the CEL on take it to any autozone store and get the code read for free. that could be a start as to why the car's doing what it is doing wrong.

[OverAllComa]

Have you tried replacing the thermostat, for starters?

[cdru]

As to the temp running cold, the thermostat and/or temp sensor would be the best starting places. It's possible the temperature and the engine running rough are related, or it could be completely different problems. The DTC hopefully will tell you more.

[cass_17_7]

Originally Posted by OverAllComa

Have you tried replacing the thermostat, for starters?

No, I haven't replaced the thermostat. It works fine when the car isn't simutaneously jerking down the road. I am going to take it to Auto Zone tomorrow and see if they can hook it up to diagnostics and see what's going on. I think it's about time for a tune-up anyways. New plugs, wires, etc. because I've noticed I don't get as good gas mileage that I used to a few months ago.

[strevo]

My car does the same thing. I had it checked and they told me I had a bad connection at the coolant temp sensor that was causing a reading of -40 degrees. THis causes the engine to dump extra gas into it to try to warm up causing the bad running and bad gas mileage. They reconnected the sensor and it ran fine for the rest of my trip (6 hours), but started doing it again on my next long trip. I haven't checked yet to see if the sensor came unconnected again. You might want to check that.
-Steve

Originally Posted by cass_17_7

No, I haven't replaced the thermostat. It works fine when the car isn't simutaneously jerking down the road. I am going to take it to Auto Zone tomorrow and see if they can hook it up to diagnostics and see what's going on. I think it's about time for a tune-up anyways. New plugs, wires, etc. because I've noticed I don't get as good gas mileage that I used to a few months ago.

[cass_17_7]

At the beginning of November we replaced the temp. sensor ourselves and my car seems to work fine after doing so. However, I still get cruddy gas mileage, I used to be able to go almost 400 miles on a tank of gas, now it's closer to 300 on a tank. Blah.