Just replaced my air box, due to cracking and leaking in dirty air. with a cone air filter...works and sounds good but one problem, there was one senser that was in the box that obviously isnt on the cone filter (its not the mass flow senser) its a little one. So i kept the senser just incase, but the other end i just taped up..but now the check engine ligh comes on right when i turn on the car.. any fixes? how bad is it for the car?
Quick guess, it's a manifold air pressure sender that goes after the air filter but BEFORE the throttle plate and the mass airflow sensor. The computer can tell it's not hooked up because it isn't seeing the pressure change at all as you rev the engine. It probably wants to confirm the MAF Sensor readings by comparing pressure before and after, and sense the filter restriction so it can pop the Check Engine light if the filter gets really clogged.
When you find out for sure, try to duplicate it's mounting with the modified air filter setup - either mount it next to the open filter with the hole open to the atmosphere, or drill a hole and put it in the side of the incoming air tube if it was "after" the filter element in the old airbox. When it gets the right signals that should make the computer happy, and the light will clear.
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I believe you are referring to the Intake Air Temperature sensor.... just a little guy, plastic body, what looks like a filament or a flat topped cone at the end opposite to the two wire connector... (I recall seeing two styles of sensor and I'm not sure which would be fitted to your car).
The PCM strategy uses IAT in fuel computations..... With the CEL on, the car is not entering closed loop operation and the fuel is being delivered at a default value (not a good deal with todays gas prices) rather than having O2 feedback for adjusting fuel delivery.
I assume your cone filter is one of those oiled elements.... not my first choice, whether it sounds good or not. And the replacement must be well thought out to lack provisions for this sensor (read that as I think they're junk.... but I am not here to rain on your parade)...
The IAT should be mounted where it can measure the temperature of the air entering the air cleaner....
Thanks Jim, Autally I have spoken to 2 of my machanic friends, and they say it is a very smart replacment to the air box. They both perform at same levels, I have taken the senser and drilled in the the rubber intake tube inserted it in, set it in some silicon gasket sealant and then cleared the code at autozone, now works perfect and i have peace of mind that my new filiter is working better than my crack old one. Thanks
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