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Thread: Losing throttle due to intake temps on LT4? Is that possible or torque tables

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    Losing throttle due to intake temps on LT4? Is that possible or torque tables

    So customers ZL1 LT4 car ran great, made awesome dyno numbers and left. Customer has been straight abusing the car which fine it should take it but they noticed the car pulling power and brought it back. After a quick ride it looks like the torque tables were pulling throttle. Before the car left on the dyno we did not have this issue. Now it seems to do it periodically like every other pull. If you put the car in a high gear and do a pull you get full throttle. It only seems to do it when the customer down shifts hard into a low gear. It'll pull some throttle and then open back up. At first I though traction control but it was off. Then I noticed the cars intake temps were at 160. Could this cause the car to pull throttle? Could it be the stability control or does it have to be the torque tables. The peak, max and actual torque all looked to line up but the max/peak numbers are maxed out on the scanner.

  2. #2
    Senior Tuner Ben Charles's Avatar
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    Never seen iat do that and I’ve tuned some with 200 MAT temps

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    Do you think it has something to do with hard downshifts because that seems to be the only time it happens. Early gears after a down shift. I can't get it to do it on the dyno but if you drive it hard on the street it pulls throttle. I'm not trying to downshift on a dyno either. It makes it tough for testing purposes

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    Have him check his heat exchanger reservoir to make sure he has plenty of coolant. I had an issue I dealt with for months where the car would lose throttle during WOT because I had a rock chip in my heat exchanger that slowly leaked a lot of coolant out over time, and IATs spiked up causing throttle loss. May not be the same issue here, but worth a look. Something in my tune was pulling the throttle due to temps but I could never figure out what, so I just replaced the heat exchanger, added coolant and never had the problem since.

  5. #5
    Senior Tuner Ben Charles's Avatar
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    Jason what you experience sounded like more low throttle and and Dom more upper RPMs.. could be related but I doubt it..

    Dom from what I know the ECU has a throttle safe point if the Fuel system is beyond maxed out, the same holds true for higher MAT temps 205+... your car felt different on different tunes Bc the “pro” shop didnt care about IAT/ECT which is MAT on the lt4.. There’s didn’t have any safe point (they removed it) where’s as the other tune would save itself “that guy knew why he was doing )

    Email Tunes, [email protected]
    96 TA Blown/Stroked, 4L80E/Fab 9
    15 C7 A8 H/C 2.3 Blower/PI
    14 Gen 5 Viper
    Custom Mid Engine chassis, AKA GalBen C

  6. #6
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    Quote Originally Posted by Ben Charles View Post
    Jason what you experience sounded like more low throttle and and Dom more upper RPMs.. could be related but I doubt it..

    Dom from what I know the ECU has a throttle safe point if the Fuel system is beyond maxed out, the same holds true for higher MAT temps 205+... your car felt different on different tunes Bc the “pro” shop didnt care about IAT/ECT which is MAT on the lt4.. There’s didn’t have any safe point (they removed it) where’s as the other tune would save itself “that guy knew why he was doing )
    Well that was the issue with why I was losing boost the whole time. A mixture of a bad heat exchanger and the tune pulling throttle due to temps. I figured it had to have been some kind of temp fail safe but unfortunately we couldn't find it while we were logging which is why I got so frustrated with it (and at that time we didn't know about the heat exchanger issue). I hate the way things turned out the way they did...