i am running a pr4 ecu in a 98 cx with a conversion harness. when i first did the swap i just left the air temp sensor that goes in the intake hanging down because i thought the pr4 ecu doesn't use that sensor, now i removed the sensor form the plug now it throws a cel and it comes on about 2 seconds after i start the car? i don't understand?

 

I would get the right ecu... but on top of that, turn the car off, d/c the batt and the ecu fuses and after about 3-5 min plug everything back up and try again

 

the right ecu? how is it not right? i have a 98 b20 non vtec. pr4 chiped and tuned on crome. obd1 ecu's dont use that sensor. so that is my question.

 

Wait a minute OBDI doesn't have an air temp sensor? I think you are wrong.

Hook back up the sensor and tuck it somewhere.
Your ECU is looking for it electrically and that is why the CEL is coming on.

I understand you are running set base maps so an IAT is not used for fuel mapping but the ECU is gonna look for it, unless chrome will let you turn it off.

If you turn it off you might still need it hooked up for the ECU to see that it is there. You are just telling chrome to not use it.

 

its not the air temperature sensor on the intake manifold, its the one on the intake arm, and i have never seen that on a obd 1 car.

 

Well if its on the arm wouldn't that be considered a mass airflow sensor?

What engine harness are you using? Maybe thats your problem.

 

intake air temp obd1 is on the manifold, obd2 is on the intake tube. the ecu still needs it either way, but you can use it in either location.

 

i have it on the intake manifold also, so are you suggesting that i put in back in the intake? becase it seems to run exactly the same with it in or out so i dont think the ecu is using it. its a 98 cx harness.

 

98 = ODBII either location is ok. But for a smogtest it has to be close to the same location as stock. And the intake arm has to be CARB legal w/a CARB number.
Because the iat is not measuring each degree. It jumps from a range, say 30-50degrees is the same reading 3.1volts then as the temps go up it would go into the next range 50-80degrees at 3.5 volts and so on.
These are not actual temp voltages just an example.

That is why is seems to not make a difference because it is still in the same range and producing the same voltages.

 

ok, well i will just put it back in i was just confused becase my ecu doesn't use that sensor with obd 1 harness, thanks for the replies.