Iat

driller

driller

El Presidente
Staff member
Hypothetically, what would the result be if the IAT was unplugged and the car was driven? Would the check engine light come on?
 
IAT - Intake Air Temperature sensor.

Intake Air Temperature (IAT) Sensor

The Intake Air Temperature (IAT) Sensor is a thermistor whose resistance decreases as manifold air temperature increases and increases as manifold air temperature decreases (Negative Temperature Coefficient or NTC). The PCM measures the voltage drop across the IAT Sensor and uses this input to help calculate fuel delivery.
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My best guess would be because the engine "leans" out the fuel mixture if it gets hot. Since the air is less dense... So JP wants to have more hands on control of the A/F curve.
 
Get one of those "chips" off of eBay and plug it in.



LMAO! just kidding, those things are a joke.

Ditto what Jeremy said. I think you'll get a CE if you smash it with a hammer too...just in case you were wondering. Lol!
 
I'll confess. :eek:

Last week I had the intake tube off while installing a new air filter. Yesterday after looking for a ground problem or short, I was wiping down the engine bay when i discovered the IAT was unplugged. Evidently I had inadvertently forgotten it when I put the intake tube back on last week!

I did not have a CEL.
 
Just for the sake of it try it on the 96 with the obd2.

Maybe the tune has something to do with it ?

I got a CEL several times on both 95 and 97 when it was unplugged for testing.
 
driller said:
I'll confess. :eek:

Last week I had the intake tube off while installing a new air filter. Yesterday after looking for a ground problem or short, I was wiping down the engine bay when i discovered the IAT was unplugged. Evidently I had inadvertently forgotten it when I put the intake tube back on last week!

I did not have a CEL.
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And we over analyzed the situation as always haha.
 
So what would the PCM do without a IAT signal? Even a better question, what would a chipped PCM do without a IAT signal? :confused:
 
driller said:
So what would the PCM do without a IAT signal? Even a better question, what would a chipped PCM do without a IAT signal? :confused:
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Dunno, but the chip being present is probably why you didn't have a code stored.

If I remember correctly the chip dumps it's data to the portion of the PCM that a trouble code would be stored.

With a chip in my car, I get a "failed PCM code".. which I'm pretty sure isn't TRUE.

I believe non existant data from the IAT would be ignored by the PCM and it'd run in some form of a failsafe mode, like the "failed maf" mode.
 
driller said:
So what would the PCM do without a IAT signal? Even a better question, what would a chipped PCM do without a IAT signal? :confused:
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The PCM will use its own "base" IAT settings if the IAT temp sensor fails(or unplugged).

A "chipped" PCM "should" do the same, but off of the tune'd portion. EVERY stock PCM will have "base" settings, if they didn't, your car would break down everytime a sensor "fails" to communicate.
 
driller said:
So I can pretty much throw my last timeslips out. lol
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I was wondering if that was "where you were going with this"...

I wouldn't chunk em.. but I dont know if I would ADD them to your caculations/spreadsheets..
But.. Keep them handy, for reference.

Hell... if yoy plug the sensor back in.. and the car slows down. who knows maybe the "default" IAT settings might work better for "consistancys sake".

I know that I pulled quite a bit of fuel from my base fuel table and that "tighten up" my ET's..not as much spread between a HOT pass and a cool down pass which is what I was "shooting for"

Think about this for a sec...

If you have ALOT of additional fuel, then your car HAS more fuel to make more power AS the temps or conditions change..

If you take away some of this "additional fuel" then the car CANT pick up as much because there isn't enough fuel to make the car "pick up".

Granted, you dont want to lean the car out during the summer months because as winter comes on.. it will probably be "too lean".

Which is why I was working on this during the cool months, and will leave it be during the summer months.

the car should "slow down" as summer comes on.. but not the .5-.6 that I lost last year.. {HOPEFULLY}
 
JP, at this stage of the game.. with the amount of money you've spent on mods and such..

You should "bite the bullet" and GET THE PRORACER PACKAGE.

I assure you you wont regret it!!!

Knowing how much you like cacluations, spreadsheets etc.. PRP is RIGHT UP YOUR ALLY BRO..
AND.. you can assist me as well {grins a selfish smile}

I need another dyed in the wool drag racer to "compare notes" and to bounce stuff off of.. if you had the PRP that'd be just what WE ALL need!

P.S. I know I've asked this question before.. but what is your catch code?
 
There is a scaler/table that addresses IAT
You can add spark and or fuel based on a particular AIT
You can add spark and or fuel or pull spark or fuel base on ECT

Alot of stuff in there that has JP written all over it.
 
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