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DFCO disable?

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Old Apr 2, 2026 | 10:54 AM
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Default DFCO disable?

Guys, qq....my 99 has an A&A v3si. Its an auto with a 3200-3500 stall. The cars runs great with one exception. I do not like the extreme engine breaking when driving 75+ and taking my foot off the gas entirely. I have not tried these changes yet as I am on vacation but I am looking at removing tcc lockup at 0 and 6% tps. I am also looking at disabling DFCO. Thoughts about disabling DFCO entirely or what I really want is disabling DFCO only at high rpms or mph. Thoughts on disabling DFCO please...
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Old Apr 7, 2026 | 01:43 PM
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It's been a while since I've messed with DFCO but, deceleration fuel cut off is what a lot of folks use to manipulate those annoying overrun pops and bangs on deceleration more than reducing engine braking. Engine braking, as far as I'm tracking, is more influenced by things like compression than anything else. But with DFCO disabled, your fuel trims will remain richer, and it'll likely smooth out tip in throttle response for when you get back onto the throttle and create a torque demand again.
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Old Apr 8, 2026 | 09:49 AM
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Originally Posted by tabbruzz
Guys, qq....my 99 has an A&A v3si. Its an auto with a 3200-3500 stall. The cars runs great with one exception. I do not like the extreme engine breaking when driving 75+ and taking my foot off the gas entirely. I have not tried these changes yet as I am on vacation but I am looking at removing tcc lockup at 0 and 6% tps. I am also looking at disabling DFCO. Thoughts about disabling DFCO entirely or what I really want is disabling DFCO only at high rpms or mph. Thoughts on disabling DFCO please...
Thank you for the feedback. It matches what I've been researching. I actually updated the tune again to keep DFCO, but did make minor adjustments to it as well as the throttle cracker. I plan to scan the changes on Friday. I actually enjoy toying around with hp tuners. My original tuner did a nice job with power, but driveabailty was not all the latest great.
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Old Apr 14, 2026 | 02:50 PM
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All good now and left DFCO functioning. Made other updates to the tune. Actually car runs better than it ever did.....
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Old Apr 21, 2026 | 02:23 PM
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If you disable DFCO you will lose MPG if you care about that.
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