Fuel filter

[gmched]

I had my car examined by car electrician. He said thermostat is working fine.
What do you mean by the fuel trim?

[pgill]

The Thermostat has two important subsystems

1) The Temperature sending unit (an electrical minded person should be able to trouble shoot this part)

2) A mechanical device that opens when the temperature rises (this is where the failure mode is likely to be found)

Long Term Fuel Trim?

If you have a device that can read PIDs (i.e. Gr/Sec for the MAF) then that device should also see the Fuel Trim Value

The way to think about Fuel Trim is it represents the deviation from the expected value.

In your case if the MAF is reading 2.5 Gr/Sec at idle and your engine is spinning at about 750 RPMs then one of two things is happening.

a) the engine computer is adding lots of fuel because the MAF signal is half of what it should be

b) the engine computer is ignoring the MAF and using the MAP to determine the amount of fuel to inject

Post the actual Fuel Trim number here and then we can talk about path forward.


Good luck

Paul

[gmched]

Hi, sorry for the late reply was busy with other staff rather that repairing the car. I wonder should I replace the thermostat, or thermostat housing? Also an interesting fact, on highway there is no increase in fuel consumption, exactly as it used to be.

[pgill]

I wonder should I replace the thermostat, or thermostat housing? Also an interesting fact, on highway there is no increase in fuel consumption, exactly as it used to be.

The Thermostat and the housing comes as an assembly.

[gmched]

I see, thank you.

[gmched]

I replaced it and it helped consumption is back to normal. The thermostat was stuck open.