ECT Sensor short with high gas mileage

[FireFire]

97 Camry I4. very poor gas mileage... about 21mpg...

My friend said check the ECT Sensor... I drain the coolant and take out the sensor. It's 0 ohm.

Question is, if the sensor is open, the gas mileage could be poor. But why the gas mileage is poor when the sensor is short?

[new echo owner]

Which coolant sensor did you check? It is either open or some resistance, shouldn't be 0 ohm. The resistance goes done when the engine warms up, if I remember correctly, and you would have experience some drivability problem too.

N.E.O.

[FireFire]

Well. I found the problem.

page 31 in coolant.pdf. That one is not the one I am looking for.

The pic shows ECT switch, which is under the fan. on the right side, at the bottom of the coolant tank. There is a No2. ECT Switch which is the real one. I took the No1 out and the resistance is 0ohm. The other one on the engine body is the real one.

I ask the ppl at partsource and he said the first one is the fan switch.

[new echo owner]

There are more than one coolant temp sensor and one coolant temp switch. Had a feeling that you had been testing the coolant temp switch for the fan.

Do you have any other drivability concern beside the poor mileage?

N.E.O.

[FireFire]

No.

It happens on Oct last year. The gas mileage goes up to 9L/100km. I try to use seafoam on Nov and seem get little bit better. The only thing I havn't done is the Oxygen Sensor.

Neo, do u have any other idea?

[new echo owner]

There are many factors that can affect fuel mileage, ECT is only one of them. And usually if the concern is related to ECT, there maybe other operation concern too. Not sure about Ontario, but some of the states in the US use winter fuel during the Winter months, which are oxygenated with Alcohol, they greatly affect the fuel mileage during the Winter months, sometimes as much as 6 to 8 mpg.

The Oxygen sensor may affect fuel mileage, however, without some ECM data, you maybe shooting in the dark about what is causing your problem.

N.E.O.

[FireFire]

I checked the brake. Clean the TB. Winter gas could be one of the reason even the winter tire. But I compare the gas mileage with last year and last last year. It still worse then the other years. It seems oxygen sensor will be my last one on the check list. I may clean the erg tomorrow if the temp really go up to +2. I don't have the code scanner so I am in dark right now.

[new echo owner]

Maybe this will be of some help to you if you want to test out some of the sensors on the vehicle: http://www.camrystuff.com/manuals/Gen4/SFI.pdf

Keep us posted on what you find.

N.E.O.

[FireFire]

Back from shopping and check the oxygen sensor. Heated oxygen sensor resistance is 17.5ohm. Gonna test it again after cooling down.