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Thread: Ditching blower on LSA, keep IAT1 or IAT2?

  1. #1
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    Ditching blower on LSA, keep IAT1 or IAT2?

    Which is the one to use to monitor air temp if switching over to turbo setup
    Factory Stock 97 SS M6 13.51 @ 104.3 mph
    Stock Longblock LS1 w/ 233/238 P.S.I. Cam
    10.81 @ 126.9 Full interior, six speed on 275 radials, a decade ago

    '99 TA trunk mounted 76mm 6 Liter
    9.0s in '09 @ 153 MPH

    Turbo 5.3 Volvo 740 Wagon
    32psi and still winding out 5th on the highway somewhere

  2. #2
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    And should I change the supercharger fitted switch to No?
    Factory Stock 97 SS M6 13.51 @ 104.3 mph
    Stock Longblock LS1 w/ 233/238 P.S.I. Cam
    10.81 @ 126.9 Full interior, six speed on 275 radials, a decade ago

    '99 TA trunk mounted 76mm 6 Liter
    9.0s in '09 @ 153 MPH

    Turbo 5.3 Volvo 740 Wagon
    32psi and still winding out 5th on the highway somewhere

  3. #3
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    Iat1 is air temp flowing past the maf (Part of the maf sensor - pre engine)
    Iat2 is air temp flowing into the engine (Part of the map sensor - air charge temp)
    You actually need to keep both iat1 and iat2 to get proper fueling calculations and just to have it run right . If your going to eliminate the maf and go VE only either keep it inline/plugged in so you get a iat1 reading or you need to wire in a stand alone iat1 sensor into the circuit so the ecm gets something and yes I would turn it off
    Last edited by TCSS07; 01-22-2019 at 07:58 PM.

  4. #4
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    Quote Originally Posted by TCSS07 View Post
    Iat1 is air temp flowing past the maf (Part of the maf sensor - pre engine)
    Iat2 is air temp flowing into the engine (Part of the map sensor - air charge temp)
    You actually need to keep both iat1 and iat2 to get proper fueling calculations and just to have it run right . If your going to eliminate the maf and go VE only either keep it inline/plugged in so you get a iat1 reading or you need to wire in a stand alone iat1 sensor into the circuit so the ecm gets something and yes I would turn it off
    Most of those PCMs only have one though?
    Factory Stock 97 SS M6 13.51 @ 104.3 mph
    Stock Longblock LS1 w/ 233/238 P.S.I. Cam
    10.81 @ 126.9 Full interior, six speed on 275 radials, a decade ago

    '99 TA trunk mounted 76mm 6 Liter
    9.0s in '09 @ 153 MPH

    Turbo 5.3 Volvo 740 Wagon
    32psi and still winding out 5th on the highway somewhere

  5. #5
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    Have one what? The iat1 sensor is in the maf and the iat2 sensor is in the map - the iat2 measures the air charge temps

  6. #6
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    Quote Originally Posted by TCSS07 View Post
    Have one what? The iat1 sensor is in the maf and the iat2 sensor is in the map - the iat2 measures the air charge temps
    You must be confused guess you missed the first line in the post where this is a turbo setup now haha. I know how they are setup factory, IAT is in the MAF but IAT2 is a stand alone sensor in the lid in LSA cars, MAP is 3 wire typical.

    The LT4 direct inject cars have a MAP/IAT combo
    Factory Stock 97 SS M6 13.51 @ 104.3 mph
    Stock Longblock LS1 w/ 233/238 P.S.I. Cam
    10.81 @ 126.9 Full interior, six speed on 275 radials, a decade ago

    '99 TA trunk mounted 76mm 6 Liter
    9.0s in '09 @ 153 MPH

    Turbo 5.3 Volvo 740 Wagon
    32psi and still winding out 5th on the highway somewhere

  7. #7
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    No I understand. I'm just saying you still need to keep both iat1 and iat2 sensors. You can't eliminate either sensor. But if all your after is to know which sensor monitors air charge temp - its the iat2

    edit: yeah forgot its a standalone on that but you still cant eliminate either sensor
    Last edited by TCSS07; 01-23-2019 at 03:25 PM.

  8. #8
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    Quote Originally Posted by TCSS07 View Post
    No I understand. I'm just saying you still need to keep both iat1 and iat2 sensors. You can't eliminate either sensor. But if all your after is to know which sensor monitors air charge temp - its the iat2

    edit: yeah forgot its a standalone on that but you still cant eliminate either sensor
    This really cant be true, because the car is only wired up to IAT1 and its running fine, IAT2 is not hooked up so you dont NEED to keep both. I know that for timing retard etc calcs in the OEM tune on LSA cars is refers to IAT2 as actual discharge temp going into engine and thats the one you would want out of the two however - what does NOT having IAT1 affect exactly? I thought it was basically an ambient pressure sensor


    Also is the IAT calibration different that I would have to change?
    Factory Stock 97 SS M6 13.51 @ 104.3 mph
    Stock Longblock LS1 w/ 233/238 P.S.I. Cam
    10.81 @ 126.9 Full interior, six speed on 275 radials, a decade ago

    '99 TA trunk mounted 76mm 6 Liter
    9.0s in '09 @ 153 MPH

    Turbo 5.3 Volvo 740 Wagon
    32psi and still winding out 5th on the highway somewhere

  9. #9
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    Apr 2011
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    Chicago, IL
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    I stated above what the iat1 was for. The iat1 sensor is pre engine airflow temp which you know but also the ecm uses that data for fueling calculations so you cant eliminate that sensor or the car isnt going to operate correctly and you shouldn't eliminate the iat2 sensor so the ecm can remove timing due to the engine air charge temps being too high. So you either need to keep the maf in line,connected and reading or install a stand alone iat1 sensor into the induction system and wire it into the ecm circuit so the ecm sees the data.
    if you want to eliminate the iat2 sensor then go ahead and just 0 out the iat correction table since it serves no purpose now but if you were to ever have a problem air charge temp wise the ecm wont beable to correct the timing to avoid knock but i suppose you could just use the low octane table for it to default to but that will usually call for way less timing then maybe a subtraction of a few degrees that the iat2 correction table would call for because the iat2 got up to 150F or so and the iat2 does play a role in fueling calculations although iat1 primarily controls that
    Last edited by TCSS07; 02-14-2019 at 06:02 PM.