Live scanner data doesn't match replayed data

Im having an IAT data issue. I have changed the IAT sensor calibration to match the new sensor, and thought everything was fine until I added a make shift antilag circuit. It manually kicks the timing into the -40deg timing column which I have set to pull timing. When looking into why that didn't work, I found that the live scanner data I see for the IAT is not what shows during a replay. The "-40deg" shown in live data with the antilag circuit active becomes 3deg in the replay. I have noticed that the IAT Spark Advance correction has a locked temp axis (at least in the spark table, i can't change it. Since the new calibration scale goes from -10 to 335deg, it doesn't match any of the other table axes which are -40 to 248. I think if I can change the temperature axis, it will solve my issue? I found, by changing the lowest value in the calibration temp axis to the same numbers as the spark axis, the replayed temp dropped from 3 deg to -16. I don't know if Im onto something there or not.

My main concern is what data is the ECU actually using? If its actually over 10deg hotter, the car won't pull timing when it should... and what other data is doing the same thing?

if yer gonna post stuff like this, especially considering where ya posted it, dontcha think listing the type of vehicle or controller in the title might be beneficial?

SAE channels can be problematic sometimes. If you have other IAT options available to you I would log that too. Obviously if your sensor is correct you should show ambient temperature on a cold engine.

Post up your sensor part number along with the calibration data and a drawing of your IAT circuit with the resistance value.

This is for an 09 Pontiac G8, E38 ecu.

I'm using a Rife: 52-1243, Only the one IAT channel to log. I have put the same data in the IAT2 table for giggles.

The IAT circuit is on a double pole, double throw relay. NC, it goes straight to the sensor. NO, is to a 130K resistor across the contacts

I have made the last two temp values -31 and -40deg (instead of 1 and -10) and kept the resistor values, the anti lag circuit now works.

Glad you got it working

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Originally Posted by hjtrbo

Glad you got it working

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Me too, but that doesn?t explain the channel/chart difference