CTS for ECU is bouncy

[hardcorandy]

According to my Autometer gauge, my water temp is 195 degrees at a fully warm idle. Link reads that my water temp bounces back and forth between 158-172. Sometimes it will bounces back and forth about 5 times in the matter of 3 seconds. I've always had high idle issues only in the winter months when its below 50 degrees outside. Im pretty sure i narrowed it down to the coolant sensor to the ECU and made changes on link to patch the problem. Idles great right now.

While warming up first thing in the morning, the gauge and the computer will match up perfect until the car reaches about 150 and then they go out of sync.

Is the sensor trashed? Anyone shed some light on this?

 

[FearlessNick]

I would go with your AM gauge. But you need to resistance test the computer sensor before ruling out a bad ECU. Before wasting money. Or even just buy a sensor to see. Then you would know it's a ECU.

 

[FearlessNick]

But I would say for sure it sounds like a sensor problem over the ECU.

 

[hardcorandy]

ECMtuning tested the Ecu a few months ago if that counts.

 

[FearlessNick]

Well did you have this problem a few months ago? Or did you just get your gauge? They could have shorted something. But I'm far from saying this is a ECU. The way you say it changes when it gets up in temperature sounds like a sensor problem.

I had to do a head job on a 89' GMC couple weeks ago and I had the same problem between the gauge sensor and the computer sensor. The gauge sensor was to high of a resistance and the gauge would peg out but the computer sensor would read the right temp.

So I have a good feeling this is a sensor problem.

 

[delta448]

Make sure your overflow bottle isn't empty. Sounds like air pockets. Could be an intermittent short, but if you're sure there's no air hitting the sensor, then it's most likely the sensor.