Fox having trouble at cold start up

[91CoupeMike]

IAT is intake air temp in #5 runner
ECT is engine coolant temp for ecm-located in heater tube)
Temp sender is for the gauge ONLY and in the left front of the lower intake, single wire

This.

[91CoupeMike]

Ok, I think i'm just referring to the wrong name. The Air Intake Temp Sensor is in the driver side of the lower intake manifold. The ECT sensor is in the heater tube on the passenger side of the lower intake manifold.

Pretty sure the AIT Sensor is utilized by the computer under cold starts and the ECT sensor is for the temp gauge. Typically a car's temp gauge is based on the coolant temp, not an air temp sensor.

Marcus

Yes, and no.

If the PCM reads the engine is cold it will Change the air/fuel ratio to aid in warm up and cold starting.

If the engine is cold and the ECT sensor thinks it's warm, it will run like crap until it's warm, like the PCM thinks.

ECT and iat work together.

[2cammer97]

Yes, and no.

If the PCM reads the engine is cold it will Change the air/fuel ratio to aid in warm up and cold starting.

If the engine is cold and the ECT sensor thinks it's warm, it will run like crap until it's warm, like the PCM thinks.

ECT and iat work together.

My understanding is the IAT ONLY sends input to the PCM under start up when the car is cold. After warming up to operating temp the IAT does absolutely nothing.

I was recommending pulling the IAT sensor out and cleaning it first, then replacing if necessary. Even at 77k miles on my '92 my IAT was pretty dirty, although wasn't affecting cold start up. Then check the ECT sensor and maybe even check the idle air control valve.

Marcus

[HUNCH]

Thank you very much for the information on this issue. I'm going to check both sensors this weekend when I have some time to work on the car. I really appreciate it and hope it's an easy fix.

[HUNCH]

I'm still confused. How can I tell if the ECT sensor is bad?