Car is STILL overheating, Need help! Options

[ILoveMySilly97]

Car:
1997 Toyota Celica GT

Location:
Central California(It's pretty hot nowadays since it's hitting summer)

When I started to notice the overheating problem:
My car ran with no over heating problem until AFTER I replaced both the ECT sensors because I had a P0115 CEL code. When I had the code my car would start then idle rough and then stall. So I bought an OBD2 CEL reader and I had the P0115 code. So I replaced both the ECT sensors and the CEL went away. The next day I was driving to Fresno(45 min drive). It drove ok(but I'm not sure because I didn't keep an eye on the gauge) until I started the car again about 6 hours later. At first it was at the correct temperature until about 15 min into the drive and I noticed it jumped up to 70% and back down. That was how and when I started the notice the over heating problem.

Problem:
Overheats once the car has been driven for about 30-40 min. My normal operating temperature is about 45%. When it starts to over heat. It'll jump up to about 65-70% then back down to about 50%. Then slowly to 45% again. Then like after another min it'll jump back up and repeat the process.

I noticed that when I was at a stop. The fan kicked in and the temp gauge jumped up to about 55% then slowly up to 70% then back down to 50% again.

EDIT: Just got back from testing my car and it seems to like to heat up to about 60% right until the fan kicks in. It'll drop to 45% then immediately and slowly climb back up to 60% and then stays there until the fan turns off. It'll slowly crawl back down to 45%. And it repeats itself. I'm thinking I might just have a faulty Coolant Temp Sensor, the one that goes to the ECU and not to the Dash. This was all done while the car was idling. Any ideas?

What I've done so far in order:
1st- Replaced both ECT sensors. 2nd- Replaced thermostat. 3rd- Replaced upper radiator hose. 4th- Flushed out the cooling system. 5th- Bled it out correctly. 6th- Replaced the radiator cap & bled it again. 7th- Checked for leaks, there were none. Coolant level stays the same.

EDIT #2: Ok. So here's an UPDATE. So. I let my car idle and heat up to about 70% and I just let it idle. It kept jumping when the fan turns on and off so I decided to unplug the sensor/switch so that the fan will always be on. When I did that trick. The gauge went down to about 45% and stayed there and never climbed or jump?

When it's connected. The fan will turn on for about 2-5 seconds max. I know that's too short. I think that's why I'm getting these problems. My fan is just not turning and staying on for the right amount of time. What I did was replaced the radiator and the fan switch. So I don't know why the fan isn't staying on for the right amount of time? Any ideas?

EDIT #3: Ok so I finally took it into a shop to test it out and they said my car is not overheating but the ECT unit isn't grounded properly because I had teflon tape on the threads. So I bought a new ECT sensor and installed it without the teflon tape. Results are NOTHING! The only relief is that it's not overheating at all. The gauge on the cluster is saying it's over heating but it really isn't. At least that's according to the mech I took it to. Any ideas about the ECT, PCM, and etc.???

This post has been edited by ILoveMySilly97: Jul 18, 2012 - 7:21 PM

[Galcobar]

With the further description, I'd also chime in on the fan switch being bad. A proper working fan switch keeps the temperature in the radiator -- and subsequently the rest of the engine -- from fluctuating. The ECT (Engine Coolant Temperature) sensor, which is the two-wire connector you circled, tells the ECU how to manipulate the air, fuel and timing. The ECU doesn't actually moderate the temperatures in the engine. That duty is left up to the thermostat which determines whether coolant needs to flow, and the radiator fan switch which determines if additional cooling is required.

Simply disconnecting the water temperature switch, which comes off the fan and is mounted on the bottom of the radiator, should cause your fans to run -- it's a safety measure, since the thermostat can keep the engine warm even if the radiator is below 83C. The water temperature switch should cause the fans to start running at 93C. To inspect the switch you'll have to remove it, which once you disconnect it is simply a matter of unscrewing it -- though you will leak coolant as a result so I'd do it when the engine is cold, and find something to temporarily plug the hole.

The water temperature switch can be inspected in the same manner as the other coolant temperature sensors, with a multi-meter and a pot of water on the stove. A key to properly testing these sensors is that they cannot be sitting on the bottom of the pot, since the pot's bottom will be a different temperature that the water. There should be continuity between the connector's terminals below 83C, and no continuity above 93C. If otherwise, replace it.