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Thread: 1996 Camaro LT1 Torqhead 24x swap high idle issues

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    1996 Camaro LT1 Torqhead 24x swap high idle issues

    Can anyone help me out with why my car has a higher idle speed when driving? The car was a 6 speed converted to a 4L60E. I have 24x swapped it prior to changing to the auto and had the car dyno tuned as well. It will only idle around 750 when under 10mph. I tried playing with the throttle cracker tables and enable/disable speeds and nothing seems to make a difference. I have my tune and log file attached. You can't see in the log but I put the car in neutral and costed several times from highway speeds down and it likes to live around 1300-1500 rpm. It's very annoying and over powers braking. I can't stand when it feel's like the car is still giving itself some throttle, when I am at 0% TPS I expect the engine to be running at the lowest RPM possible.
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    Can anyone help?

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    Senior Tuner Ben Charles's Avatar
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    Throttle cracker

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    Thank you.

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    Quote Originally Posted by k20chevy View Post
    Can anyone help me out with why my car has a higher idle speed when driving? The car was a 6 speed converted to a 4L60E. I have 24x swapped it prior to changing to the auto and had the car dyno tuned as well. It will only idle around 750 when under 10mph. I tried playing with the throttle cracker tables and enable/disable speeds and nothing seems to make a difference. I have my tune and log file attached. You can't see in the log but I put the car in neutral and costed several times from highway speeds down and it likes to live around 1300-1500 rpm. It's very annoying and over powers braking. I can't stand when it feel's like the car is still giving itself some throttle, when I am at 0% TPS I expect the engine to be running at the lowest RPM possible.
    Yep Throttle cracker. You said you tried that? It should be 0 in the 400-1600rpm and from 0-24mph.

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    Hi, and yes I have throttle cracker off on the tune. I was able to use throttle follower just a tad to get it to cushion the down rev so it wouldn't drop super fast. But what it does now is it revs down, then on its own (not every time) it calls for a ton of air and revs back up 200ish rpm then returns to idle. My fuel trims go off the charts stft, is like 30+ on bank 2 and -30 on bank one. Keep in mind this car was dyno tuned with the ve table. I notice I get crap readings at idle from both 02 banks. They hardly swing and are get lazy to read.

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    Quote Originally Posted by k20chevy View Post
    Hi, and yes I have throttle cracker off on the tune. I was able to use throttle follower just a tad to get it to cushion the down rev so it wouldn't drop super fast. But what it does now is it revs down, then on its own (not every time) it calls for a ton of air and revs back up 200ish rpm then returns to idle. My fuel trims go off the charts stft, is like 30+ on bank 2 and -30 on bank one. Keep in mind this car was dyno tuned with the ve table. I notice I get crap readings at idle from both 02 banks. They hardly swing and are get lazy to read.
    Can you post your base tune? What mods have been done? Throttle cracker removed in that range should help the hanging idle while driving but that assumes the base running airflow is real close. For consistency I would set the idle at 750 RPM for ac on or off or leave ac off during this. I am comparing your 1 final test 5 tune against my stock 2002 ss and z-28 files.
    Looks like you adjusted the adaptive idle parameters that are controlled by the P.I.D. loop. I will stop here, if you know how to control the feedback loop of Proportional, Integral, and Derivative controller then I will not be of much help. I know the logic basics but the calibration has been done by GM better than I could. Now my job as a tuner is to get the Base parameters within the loops ability to function. I personally would return these settings to stock along with O2 feedback, IAC steps, MBT timing, idle flare, I could go on but really without list of motor mods its fruitless.

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    Which base tune should I upload? Being a converted car, the base tune is a barely modified LS1 stock tune that comes with the kit. The setup is a LT1 with a comp cams 503 cam. 224/230 @.050, .536 intake lift (with 1.6 roller rockers) .544 exhaust. It's got longtube headers, cold air intake, 3 inch exhaust from the off road Y pipe all the way back. Stock cleaned MAF, stock intake and throttle body. https://www.deatschwerks.com/18u-01-0042-8 42lb injectors, running @ 58psi and tuned at that level.

    I was testing the adaptive idle settings to see if it would help or hurt my situation, so far by the time I notice it kicking in, it's well after the car dips down in idle. Right now the car idle's better without adaptives on. The dyno shop has adjusted the 02 settings, and everything else. The IAC had to be changed to get the car to even idle since it's not a monoblade TB. I am happy to try that advice and see what happens, I should be able to get to my car this weekend to test.