Low rpm tuning
Thread Starter
TECH Resident
Joined: Sep 2019
Posts: 822
Likes: 262
From: Melbourne, Australia
Low rpm tuning I’m street tuning my car and I’m getting low rpm back fires. The engine is a lsx454 solid roller 258/272 cam on a speed density tune, E38pcm
Above 2500rpm the tunes sweet, I get back fires coasting down, I’m thinking because there so much overlap on the cam I’m getting lean back fires.
Does tht sound rite?
How do I dial the tune in with lots of overlap?
Above 2500rpm the tunes sweet, I get back fires coasting down, I’m thinking because there so much overlap on the cam I’m getting lean back fires.
Does tht sound rite?
How do I dial the tune in with lots of overlap?
TECH Fanatic
Joined: Dec 2017
Posts: 1,469
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From: Bossier City, Louisiana
Maybe your tuner has left "Decel Fuel Cutoff" turned off in the operating system??? In other words, he left the fuel running just a little during engine coasting for deceleration. This can be turned off if you don't like the exhaust burbling a little.
Rick
Rick
Thread Starter
TECH Resident
Joined: Sep 2019
Posts: 822
Likes: 262
From: Melbourne, Australia
Thread Starter
TECH Resident
Joined: Sep 2019
Posts: 822
Likes: 262
From: Melbourne, Australia
Yes I agree that if you want to hv good street manners , go with less overlap
Im not interested in street manners, I would just like some advice on how to best tune your car for low rpm when you hv lots of overlap
I’ll just go back to tune 1 and copy and paste paste everything under 2500rpm. That will fix it
Im not interested in street manners, I would just like some advice on how to best tune your car for low rpm when you hv lots of overlap
I’ll just go back to tune 1 and copy and paste paste everything under 2500rpm. That will fix it
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I had similar issues with my setup, a 454 LS with a 239/251 @ 114 cam, and P59 PCM.
Enabling DFCO helps a lot, but it takes a second for the fuel to cut off, so it's a necessary step but not entirely sufficient. Disable throttle cracker was the other key thing, it made a huge difference.
Disabling throttle cracker then screwed up return-to-idle, and the fix for that was a setting that causes adaptive idle to kick in at about 1500 RPM, so that it can handle the transition to idle proactively instead of just reactively.
It's all good now. No pop/bang on decel, and consistent return-to-idle.
Enabling DFCO helps a lot, but it takes a second for the fuel to cut off, so it's a necessary step but not entirely sufficient. Disable throttle cracker was the other key thing, it made a huge difference.
Disabling throttle cracker then screwed up return-to-idle, and the fix for that was a setting that causes adaptive idle to kick in at about 1500 RPM, so that it can handle the transition to idle proactively instead of just reactively.
It's all good now. No pop/bang on decel, and consistent return-to-idle.
