Strange IAT problem need some help!
11-09-2013, 07:47 PM
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Strange IAT problem need some help! I have a really strange issue, when logging my car via hptuners my intake air temps are 270-285 wheather the car is started or not, whether its ice cold or not. normally when you unplug the sensor it defaults to -32 or something mine will not it remains at 270+. Now i thought i had a bad sensor so i bought a new one and same thing, so i though ok maybe i got a bad one so i ordered a new one and same issue. I check continuity to the sensor and everything apears to be ok, and the pigtail itself seems ok. I have searched all over the forums and cant find anything.
11-09-2013, 07:57 PM
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Pull the sensor and measure ohms (with a meter that
applies a reasonably low voltage - like most modern
DMMs). This sounds like a IAT-GND short to me, low
IAT resistance equals high temp and yours looks
pegged at underrange-low.
Continuity on either single wire will look just fine
when you have a short. But there should be no
continuity -between-.
applies a reasonably low voltage - like most modern
DMMs). This sounds like a IAT-GND short to me, low
IAT resistance equals high temp and yours looks
pegged at underrange-low.
Continuity on either single wire will look just fine
when you have a short. But there should be no
continuity -between-.
11-10-2013, 12:18 PM
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What I mean is, pull the IAT and measure the resistance
between the two harness wires. Try to keep the ohms
polarity right (black = the IAT ground). If you read under
a megohm something's not really right and near zero you
have a short-to-ground (whether PCM, sheet metal or
something else in the bundle).
PCM will force current when lit up, you'd do this with
power off. Don't know what a proper voltage would be
across the IAT in place, at normal-range temps, but
that would be another way to check (if somebody has
written down IAT voltage @ temp somewhere).
between the two harness wires. Try to keep the ohms
polarity right (black = the IAT ground). If you read under
a megohm something's not really right and near zero you
have a short-to-ground (whether PCM, sheet metal or
something else in the bundle).
PCM will force current when lit up, you'd do this with
power off. Don't know what a proper voltage would be
across the IAT in place, at normal-range temps, but
that would be another way to check (if somebody has
written down IAT voltage @ temp somewhere).
