Thermostat or bad temperature sensor ????

[jlagu]

After reading quite a bit in this excellent forum and checking bad mpg and other symthoms
I think I've got a bad temp sensor or a thermostat that is stuck.
how can I check if any of this is true?
I think the ECU tries to heat the engine all the time , with a bad mpg.
I have basicaly the same mpg with the ac on or off, driving in city or highway.

Symtoms : hesistates to accelerate when engine is hot. Doesn´t happen with cold engine.

Thank you very much.

Lanos 1.4i manual , new oil, new filters , new bosch 4 spark plugs ,TB cleaned (october year 2000) only 35000 Km about 22000 milles.

[jlagu]

Have had a look at the temp sensor , the thing seems quite easy to unscrew.
How could I check if it's working properly? Or should I just buy a new one . Doesn´t look expensive.
How much could it cost?

Thanks

[GsiTurbo]

My first guess would be bad coolant temp sensor (TPS)... Also check your IAT (intake air temp) sensor too. If its shot and tell computer its -30C outside, it will run rich at all times.

Tom

[jlagu]

How can I check both IAT and coolant temp sensor. I mean using my own hands. Both are easy to unscrew, but how do I know if they are working well.

[MMamdouh]

i guess you need a scan tool to see the actual reading of the sensors and compare it to real life values at the time of the tesdt.

MMamdouh

[GsiTurbo]

How can I check both IAT and coolant temp sensor. I mean using my own hands. Both are easy to unscrew, but how do I know if they are working well.

Without knowing its resistance at given temp, you cannot really test them. But since both parts are relatively inexpensive (about $10-20 each), I'd replace them.