Which or what sensor senses the air coming into the engine
 

Not sure how to ask this, but let me try.

Which or what sensor senses the air coming into the engine or which sensor monitor whether the engine is warm, hot or cold and decides what to do or how to idle the engine?


i noticed that when its too hot or too cold, my engine reacts differently, sometimes it vibrates, sometimes the idle is higher, etc.

Everything is OK and normal when the temperature outside is around 70 to 80

1991 Honda Accord DX

Engine uses Intake Air Temperature (IAT), Manifold Air Pressure (MAP), and probably RPM to estimate air flow rate and mix fuel to achieve acceptable air/fuel ratio cold. When warmed, the O2 sensor senses oxygen content and fuel delivery is adjusted to attain approximately correct air/fuel ratio (14.7/1).

Engine idle is adjusted by idle air control valve and ECM to achieve predetermined idle speeds based on coolant temp, air temp.

Rough idle can be caused by many problems besides air flow rate; intake air leak, motor mount fault, loss of spark problems.

Is Check Engine Light ever On? If yes, see DIY forum for guidance on extracting Obd1 codes.

good luck

Thanks. Lots of good info.

And the ECT tells the ECU the temp of the engine coolant....which "plays" with the others listed.

But again, checking for codes and testing are need before doing anything else.